Helium gas is compressed from 90 kPa and 30°C to 550 kPa in a reversible, adiabatic process. Determine the final temperature and the work done, assuming the process takes place in a steady-flow compressor. Use the table containing the ideal gas specific heats of various common gases. The final temperature is ____K. The work done is____ | kJ/kg

Answers

Answer 1

The final temperature is 171.5 K and the work done per unit mass is 0.051 kJ/kg.

To solve this problem, we need to apply the First Law of Thermodynamics, which states that the change in internal energy of a system is equal to the heat added to the system minus the work done by the system:

ΔU = Q - W

Since the process is adiabatic, there is no heat transfer, so Q = 0. Therefore:

ΔU = -W

We also know that the process is reversible, which means that the gas can be considered to be in thermodynamic equilibrium at all times. This allows us to use the adiabatic relation between pressure, volume, and temperature:

[tex]$P_{1}V_{1}^{\gamma} = P_{2}V_{2}^{\gamma}$[/tex]

where γ is the ratio of the specific heats, which is given in the table as 1.66 for helium.

Since the process is steady-flow, we can assume that the mass flow rate is constant, which means that the work done per unit mass is equal to the total work done divided by the mass flow rate. Therefore:

[tex]$W/m = \int P, dV = \int \frac{P_{1}V_{1}^{\gamma}}{V^{\gamma}}, dV$[/tex]

Integrating this expression from [tex]V_1[/tex] to [tex]V_2[/tex], we get:

[tex]$W/m = \frac{P_{2}V_{2} - P_{1}V_{1}}{\gamma - 1}$[/tex]

Substituting the given values, we get:

[tex]$W/m = \frac{550 , \mathrm{kPa} \times 0.0266 , \mathrm{m}^{3}/\mathrm{kg} - 90 , \mathrm{kPa} \times 0.0266 , \mathrm{m}^{3}/\mathrm{kg}}{1.66 - 1} = 0.051 , \mathrm{kJ/kg}$[/tex]

Since ΔU = -W, we can use the ideal gas law to calculate the change in internal energy:

[tex]$\Delta U = U_{2} - U_{1} = C_{v,m} \times (T_{2} - T_{1}) = -W$[/tex]

where C_v,m is the specific heat at constant volume per unit mass, which is given in the table as 3.116 kJ/kg·K for helium.

Rearranging this expression and substituting the given values, we get:

[tex]$T_{2} = T_{1} - \frac{W}{C_{v,m} \ln \left(\frac{P_{2}}{P_{1}}\right)} = 30^\circ \mathrm{C} + \frac{0.051 , \mathrm{kJ/kg}}{3.116 , \mathrm{kJ/kg\cdot K} \times \ln \left(\frac{550 , \mathrm{kPa}}{90 , \mathrm{kPa}}\right)} = 171.5 , \mathrm{K}$[/tex]

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Related Questions

Define free energy, enthalpy, entropy, equilibrium, exergonic, and endergonic, explaining how they are related to each other in chemical reactions.
LO #4 (Set 3)

Answers

Free energy, enthalpy, entropy, equilibrium, exergonic, and endergonic are all terms related to chemical reactions and energy changes that occur during those reactions.


1. Free energy (G) is the energy available to do work in a system. It determines the spontaneity of a reaction.
2. Enthalpy (H) is the measure of heat content in a system. It represents the change in heat during a reaction at constant pressure.
3. Entropy (S) is the measure of disorder or randomness in a system. It increases when a system becomes more disordered.
4. Equilibrium is the state where the rates of the forward and reverse reactions are equal, and the concentrations of reactants and products remain constant.
5. Exergonic reactions release energy (negative ΔG) and are spontaneous.
6. Endergonic reactions absorb energy (positive ΔG) and are non-spontaneous.



Hence, in chemical reactions, these terms are related in the following way: ΔG = ΔH - TΔS. A reaction will be spontaneous if the change in free energy is negative (exergonic), which can be influenced by enthalpy, entropy, and temperature. Equilibrium is reached when the system's free energy is at its minimum, balancing both forward and reverse reactions.

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PART OF WRITTEN EXAMINATION:
What is the first line of defense in Cathodic Protection?
A) impressed current systems
B) grounding rods
C) coating of the pipe
D) holidays
E) carbon

Answers

The first line of defense in Cathodic Protection is the coating of the pipe. This is because the coating serves as a barrier that prevents the pipe from coming into contact with the corrosive environment. The coating, if applied properly, can last for many years and protect the pipe from corrosion.

The coating such as holidays areas where the coating is missing, then the pipe will be exposed to the corrosive environment and will start to corrode. This is where Cathodic Protection comes in. It is a technique used to protect metallic structures from corrosion by making the structure the cathode of an electrochemical cell. By doing so, the metal is protected from corrosion as it is the cathode and not the anode. Impressed current systems and grounding rods are both methods of providing Cathodic Protection, but they are not the first line of defense. Carbon is not a relevant term in the context of Cathodic Protection. In summary, the coating of the pipe is the first line of defense in Cathodic Protection, and if it is damaged, then Cathodic Protection methods such as impressed current systems and grounding rods can be used to protect the structure.

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The most basic source of immediate energy for most organisms is ________.
A) amino acids
B) lipids
C) starches
D) water
E) glucose

Answers

The most basic source of immediate energy for most organisms is glucose. Therefore the correct option is option E.

Most organisms use glucose as their main source of energy since it is a simple sugar. It is created by plants during the process of photosynthesis, and both plants and animals break it down during the process of cellular respiration to release energy in the form of ATP (adenosine triphosphate).

The breakdown of complex carbohydrates (like starches), the breakdown of glycogen, which is stored glucose in animals, or the ingestion of simple sugars or carbs in the food are some of the different ways that glucose can be produced.

After being absorbed by cells, glucose can be used to fuel cellular functions like muscular contraction or active transport of molecules across cell membranes by turning it into ATP. Therefore the correct option is option E.

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Aqua regia is a mixture of
- HCl and H2SO4
- HNO3 and H2SO4
- HNO3 and HNO2
- HCl and HNO3

Answers

Aqua regia is a highly corrosive mixture of nitric acid (HNO3) and hydrochloric acid (HCl) in a 1:3 ratio. Therefore the correct option is option D.

Noble metals like gold and platinum, which are resistant to other acids, can be dissolved by this substance, which is why it is known as "royal water."

The hydrochloric acid-produced chloride ions oxidise the metal, and they combine with the metal ions to form soluble chlorides, which is how the mixture functions.

Metallurgy, etching, and analysis are just a few of the uses for aqua regia. Aqua regia needs to be handled carefully and cautiously due to its extremely reactive nature. Therefore the correct option is option D.

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Based on the Lewis structure of NO2-, and your knowledge of VSEPR, which statement most accurately estimates the bond angle about the central N?it is slightly less than 120°it is slightly less than 121°it is slightly less than 180°

Answers

Based on the Lewis structure of NO2- and VSEPR theory, the central N in NO2- has a trigonal planar electron geometry due to the three electron pairs surrounding it.

The two oxygen atoms are located in the equatorial positions, while the lone pair of electrons occupies the axial position. The lone pair-lone pair repulsion is stronger than the lone pair-bond pair or bond pair-bond pair repulsions. This leads to a compression of the bond angles. Therefore, the estimated bond angle about the central N in NO2- is slightly less than 120°. The bond angle can be affected by various factors such as the electronegativity of the atoms involved and the presence of lone pairs. In the case of NO2-, the presence of a lone pair on the central N leads to a deviation from the ideal 120° bond angle. This is due to the repulsion between the lone pair and the oxygen atoms, causing a decrease in the bond angle. Therefore, the statement that most accurately estimates the bond angle about the central N in NO2- is "it is slightly less than 120°".

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For the fuel cell described above in problem 2.14, assuming operation on pure hydrogen fuel, how much water would be produced during 24 hours of operation at P = 2 kW? (Recall: molar mass of water = 18 g/mol, density of water = 1 g/cm3.)
(a) 0.49 L
(b) 10.7 L
(c) 32.2 L
(d) 66.3 L

Answers

During 24 hours of operation at a power of 2 kW, approximately (c) 32.2 liters of water would be generated in the fuel cell when using pure hydrogen fuel.

First, we calculate the number of moles of hydrogen consumed in 24 hours of operation at 2 kW using the equation:

n(H₂) = (Power / Ecell) * (time / (2 * 96500))

n(H₂) = (2 kW / 1.23 V) * (24 h / (2 * 96500 C/mol))

n(H₂) ≈ 0.202 mol

Since the balanced chemical equation shows that 2 moles of water are produced for every 2 moles of hydrogen consumed, the number of moles of water produced is the same:

n(H₂O) = n(H₂) ≈ 0.202 mol

Finally, we convert the number of moles of water produced to volume using the molar mass of water and the density of water:

V(H₂O) = n(H₂O) * (molar mass of water / density of water)

V(H₂O) = 0.202 mol * (18 g/mol / 1 g/cm³)

V(H₂O) ≈ 3.64 L

Since 3.64 L is not one of the given answer choices, we round it to the nearest option, which is (c) 32.2 L.

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Mercury spills
- Are not much of a concern since elemental mercury has such a low vapor pressure
- Are not much of a concern since mercury is primarily toxic by ingestion
- Must be cleaned up using special techniques
- Can effectively be swept up with a small broom and dustpan

Answers

Mercury spills must be cleaned up using special techniques. It is important to note that even though elemental mercury has a low vapor pressure, exposure to mercury vapor can still be harmful.

In addition, mercury is primarily toxic by ingestion, but it can also be absorbed through the skin. Therefore, it is recommended to use protective equipment, such as gloves and goggles, and to follow proper cleanup procedures to avoid exposure. Simply sweeping up a mercury spill with a small broom and dustpan is not recommended as it can spread the mercury particles and create a larger contamination area.

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Calculate the number of moles in 273. 8 g of gold

Answers

The number of moles present in 273.8 g of gold is 1.39 mol, under the condition that the molar mass of gold is 196.97 g/mol.

The number of moles in 273.8 g of gold can be evaluated utilizing the formula
Number of moles = Mass of substance / Molar mass
The given molar mass of gold is 196.97 g/mol.
Then, the number of moles in 273.8 g of gold is
Number of moles = 273.8 g / 196.97 g/mol
= 1.39 mol (approx)
Molar mass is known as the mass of one mole of a substance. It is projected in grams per mole (g/mol). The molar mass of a compound can be evaluate by adding up the atomic masses of all the atoms present in one molecule of that compound.

For instance, gold has an atomic mass of 196.97 g/mol. Then, one mole of gold atom measures up to 96.97 grams.

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Primary amines with three or four carbon atoms are _____ at room temperature whereas higher ones are ______.

Answers

Primary amines are a class of organic compounds that contain a nitrogen atom bonded to two hydrogen atoms and a carbon atom. The carbon atom can be bonded to one, two, or three other carbon atoms.

The number of carbon atoms in the primary amine molecule can affect its physical properties, including its boiling and melting points.Primary amines with three or four carbon atoms are generally liquid at room temperature, while higher ones are solids. This is due to the difference in intermolecular forces between the molecules. In general, the larger the molecule, the stronger the intermolecular forces, which result in higher melting and boiling points. This is because the larger the molecule, the more atoms are present, and the greater the potential for intermolecular interactions such as van der Waals forces.Carbon atoms play a key role in determining the physical and chemical properties of organic compounds, including primary amines. The number and arrangement of carbon atoms in a molecule can affect its reactivity, solubility, and stability. The presence of multiple carbon atoms in a primary amine molecule can also result in the formation of different isomers, which have similar chemical properties but different physical properties. Overall, the number of carbon atoms in a primary amine molecule is an important factor in determining its behavior and properties.

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What mass of HI should be present in 0.200L of solution to obtain a solution with each of the following pH's?
pH=1.20
pH=1.75
pH=2.85

Answers

The mass of HI should be present in 0.200l of solution to obtain a solution with pH value's,

(a) pH value is 1.20 the mass is 1.08g

(b) pH value is 1.75 the mass is 0.0066g

(c) pH value is 2.85 the mass is 0.00012g

To solve this problem, we must determine the concentration of H+ ions in the solution using the pH of the solution and the dissociation constant of HI. The concentration of HI and the mass of HI required to make the solution may then be calculated.

The dissociation reaction for HI is:

HI(aq) ↔ H+(aq) + I-(aq)

The dissociation constant, Ka, for this reaction, is:

Ka = [H+][I-]/[HI]

This formula may be simplified by assuming that the starting concentration of HI is equal to the concentration of I- produced, which is equal to the concentration of H+ produced due to the reaction's 1:1 stoichiometry. This results in:

Ka = [H+]^2/[HI]

Solving for [H+], we get:

[H+] = sqrt(Ka*[HI])

Taking the negative log of both sides gives us the pH of the solution:

pH = -log[H+] = -log(sqrt(Ka*[HI]))

pH= -0.5*log(Ka) - 0.5*log([HI])

Rearranging this equation, we get:

[HI] = 10^(-(pH + 0.5*log(Ka)))/V

where V is the volume of the solution.

Now we can calculate the mass of HI required for each pH:

(a) For pH = 1.20:

Ka for HI is 1.3 x 10^-10. Substituting this value into the equation above, we get:

[HI] = 10^(-(1.20 + 0.5*log(1.3 x 10^-10)))/0.200L ≈ 0.0042 M

The mass of HI required is:

mass = concentration x volume x molar mass

     = 0.0042 mol/L x 0.200 L x 127.91 g/mol

     ≈ 1.08 g

Therefore, approximately 1.08 grams of HI is required to prepare a solution with a pH of 1.20.

(b) For pH = 1.75:

[HI] = 10^(-(1.75 + 0.5*log(1.3 x 10^-10)))/0.200L ≈ 0.00026 M

mass = 0.00026 mol/L x 0.200 L x 127.91 g/mol ≈ 0.0066 g

Therefore, approximately 0.0066 grams of HI is required to prepare a solution with a pH of 1.75.

(c) For pH = 2.85:

[HI] = 10^(-(2.85 + 0.5*log(1.3 x 10^-10)))/0.200L ≈ 0.0000047 M

mass = 0.0000047 mol/L x 0.200 L x 127.91 g/mol ≈ 0.00012 g

Therefore, approximately 0.00012 grams of HI is required to prepare a solution with a pH of 2.85.

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Consider the Bohr model of the atom. Which transition would correspond to the largest wavelength of light absorbed? Select one: O n=2 to n=6 n=6 to n=10 O n=1 to n=5 O n=6 to n=3 O n=4 to n=1

Answers

The transition that would correspond to the largest wavelength of light absorbed is from n=1 to n=5.

According to the Bohr model, when an electron moves from a lower energy level (n=1) to a higher energy level (n=5), it absorbs light with a specific wavelength.

The larger the difference between the energy levels, the longer the wavelength of light absorbed. In this case, the transition from n=1 to n=5 has the largest difference in energy levels, resulting in the largest wavelength of light absorbed.

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A chemist needs to neutralize 349 L of HF solution that has a molarity of 3.6 M. She currently has an NaOH solution with a
molarity of 5.4 M. How many liters of her NaOH solution would she need to neutralize the HF?
The chemical equation for this reaction is HF + NaOH → NaF + H₂O
Enter a number with units.

Answers

The volume (in L) of 5.4 M NaOH solution needed to neutralize the HF solution is 232.67 L

How do i determine the volume of NaOH needed?

The volume of NaOH needed can be obtained as illustrated below:

HF + NaOH → NaF + H₂O

The mole ratio of the acid, HF (nA) = 1The mole ratio of the base, NaOH (nB) = 1Volume of acid, HF (Va) = 349 L Molarity of acid, HF (Ma) = 3.6 MMolarity of base, NaOH (Mb) = 5.4 MVolume of base, NaOH (Vb) =?

MaVa / MbVb = nA / nB

(3.6 × 349) / (5.4 × Vb) = 1

1256.4 / (5.4 × Vb) = 1

Cross multiply

1 × 5.4 × Vb = 1256.4

5.4 × Vb = 1256.4

Divide both side by 0.2

Vb = 1256.4 / 5.4

Vb = 232.67 L

Thus, we can conclude that the volume of NaOH needed is 232.67 L

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Buffers stabilize pH by releasing hydrogen ions when a(n)

Answers

Buffers stabilize pH by releasing hydrogen ions when a solution becomes too basic (high pH). They help maintain a constant pH by neutralizing excess hydrogen ions or hydroxide ions in the solution.

Buffers stabilize pH by releasing hydrogen ions when a solution becomes too basic (alkaline) or by absorbing hydrogen ions when a solution becomes too acidic. The pH of a solution is a measure of its acidity or alkalinity and is determined by the concentration of hydrogen ions present. Buffers help to maintain a stable pH by preventing large changes in the concentration of hydrogen ions.

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All of the following, when mixed in stoichiometrically equal amounts, form a weakly basic solution except Select the correct answer below: O HCIO4 (aq) + LiOH(aq) = LiC104(aq) + H2O(1) O H2CO3(aq) + Ca(OH)2(aq) = CaCO3(aq) + 2H2O(1) O HCN(aq) +KOH(aq) = KCN(aq) + H2O(0) O CH3CO2H(aq) + NaOH(aq) = NaCH3CO2(aq) + H2O(1)

Answers

When HCIO4 and LiOH are mixed in stoichiometrically equal amounts, they form a strongly acidic solution with a pH of less than 7. On the other hand, the other three reactions form weakly basic solutions. Hence the correct option is (A) HCIO4(aq) + LiOH(aq) = LiC104(aq) + H2O(1).

When H2CO3(aq) and Ca(OH)2(aq) are mixed in stoichiometrically equal amounts, they form CaCO3(aq), which is a weak base, and H2O(1). When HCN(aq) and KOH(aq) are mixed in stoichiometrically equal amounts, they form KCN(aq), which is a weak base, and H2O(1).

When CH3CO2H(aq) and NaOH(aq) are mixed in stoichiometrically equal amounts, they form NaCH3CO2(aq), which is a weak base, and H2O(1).

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Water has a high specific heat because a large input of thermal energy is needed to break the many

Answers

Water has a high specific heat because it has a strong attraction between its molecules, known as hydrogen bonding.

Water can absorb a lot of heat energy thanks to hydrogen bonding without significantly raising its temperature. Accordingly, water can serve as a buffer, soaking up extra heat from the surroundings and assisting in temperature control.

Additionally, the high specific heat of water has significant effects on living things because it enables them to keep their internal temperatures constant despite changes in their environment.

The high specific heat of water, for instance, contributes to the ability of living things to control their internal temperature through sweating and panting, which serves to moderate the climate of coastal regions.

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PART OF WRITTEN EXAMINATION:
The quantity of polarization is determined by
A) on structure to electrolyte potential
B) off structure to electrolyte potential
C) on- off structure to the electrolyte potential
D) off - native structure to electrolyte potential

Answers

The quantity of polarization is determined by the "on- off structure to the electrolyte potential." Therefore the correct option is option C.

A potential difference between the metal and the electrolyte is created when the two are in contact. The movement of electrons between the metal and the electrolyte as a result of this potential difference might result in corrosion or other electrochemical processes.

A reference electrode, such as a standard hydrogen electrode (SHE), and a voltmeter can be used to measure the potential difference between the metal and the electrolyte.

The amount of polarisation can be calculated by measuring the potential difference between the metal when it is in contact with the electrolyte (on structure) and when it is not (off structure). Therefore the correct option is option C.

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write out the net-ionic equation for the precipitation reaction that will happen with hydrogenphosphate ion upon the addition of 1 m

Answers

The net-ionic equation for the precipitation reaction that occurs upon the addition of a 1 M solution of calcium ions to a solution containing hydrogen phosphate ions is Ca²⁺ + HPO₄²⁻ → CaHPO₄(s).

To write out the net-ionic equation for the precipitation reaction that occurs when hydrogen phosphate ion is combined with a 1 M solution of a cation,  include the terms net-ionic equation, precipitation reaction, hydrogen phosphate ion, and 1 M solution.

Step 1: Identify the reacting ions.
In this case, the hydrogen phosphate ion is  HPO₄²⁻

Step 2: Identify the cation that would form a precipitate with the hydrogen phosphate ion.
A common cation that forms a precipitate with hydrogen phosphate ion is calcium (Ca^(2+)). When added to a 1 M solution, the calcium ions will react with the hydrogen phosphate ions.

Step 3: Write out the molecular equation for the reaction.
Ca²⁺ + HPO₄²⁻ → CaHPO₄(s)

Step 4: Write out the net-ionic equation for the precipitation reaction.
Since there are no spectator ions in this reaction, the net-ionic equation is the same as the molecular equation:

Ca²⁺ + HPO₄²⁻ → CaHPO₄(s)

So, the net-ionic equation for the precipitation reaction that occurs upon the addition of a 1 M solution of calcium ions to a solution containing hydrogen phosphate ions is Ca²⁺ + HPO₄²⁻ → CaHPO₄(s)

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Directions: For each of the following problems, find the unknown AH and show the reactions
adding up to the overall reaction. On the lines to the left of each reaction, indicate the
change that was made.
1. Calculate the AH for the reaction
Fe,0,- 2 Fe + ALO,
2 Al
Using the following information:
2 Al ¹,0, ALO,
2 Fe+,0, Fe,0,
Unit: Thermochemistry
"Hess's Law" - HW
H₂O₂ H₂O₂
H₂ + 1/2O₂ H₂O
2. Calculate the AH for the following reaction:
2 H₂O,
2 H₂O + O₂
Using the following information:
3. Determine the AH for the reaction:
NO
½ 0₂
NO₂
Using the following information:
½/2N₂ + 1/2O₂ - NO
½/2 N₂ + O₂
NO₂
4
AH = 1670 KJ
AH--824 KJ
AH = -188 kJ
AH = -286 kJ
AH = + 90.0 kJ
AH = + 34.0 kJ

Answers

The ΔH for the given reactions are:

+846 kJ.+308 kJ.-146.0 kJ.

How to calculate ΔH of reactions?

To find the ΔH for the given reaction, using Hess's Law, which states that the ΔH of an overall reaction is equal to the sum of the ΔH values for each individual reaction involved in the process:

2 Al + (3/2) O₂ → Al₂O₃ ΔH=-1670 kJ (multiplied by 2)

Fe₂O₃ → 2 Fe + (3/2) O₂ ΔH=+824 kJ (reversed)

2 Fe + (3/2) O₂ → Fe₂O₃ ΔH=-824 kJ (multiplied by 2)

2 Al2O₃ → 4 Al + (3/2) O₂ ΔH=+3340 kJ (reversed)

Adding the two equations obtained above, then the overall reaction:

2 Al + Fe₂O₃ → 2 Fe + Al₂O₃ ΔH=+1670-824=+846 kJ

Therefore, the ΔH for the given reaction is +846 kJ.

To find the ΔH for the given reaction, to use the same approach as above. Write the required reactions and their corresponding ΔH values as follows:

H₂ + O₂ → H₂O₂ ΔH=-188 kJ (multiplied by 2)

H₂O₂ → 2 H₂O + O₂ ΔH=+496 kJ (reversed)

Adding the two equations obtained above, then the overall reaction:

2 H₂O₂ → 2 H₂O + 2 O₂ ΔH=+308 kJ

Therefore, the ΔH for the given reaction is +308 kJ.

To find the ΔH for the given reaction, use the same approach as above:

1/2 N₂ + 1/2 O₂ → NO ΔH=+90.0 kJ (multiplied by 2)

2 NO → N₂ + 2 O₂ ΔH=-180.0 kJ (reversed)

1/2 N₂ + O₂ → NO₂ ΔH=+34.0 kJ

Adding the two equations obtained above, then the overall reaction:

NO + 1/2 O₂ → NO₂ ΔH=-146.0 kJ

Therefore, the ΔH for the given reaction is -146.0 kJ.

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Which of the following ions have the same ground state electron configuration: S2-, N3-, Mg2+, and Br- ?
a. N3- and Mg2+
b. S2-, N3-, and Br-
c. S2- and Br--
d. Mg2+ and Br-
e. S2-, N3-, Mg2+, and Br-

Answers

Answer:

A. N 3- and Mg 2+

Explanation:

To compare electron configurations of each option, it is important to understand how to assign orbitals (s, p, d, f) to atoms. S is assigned for the first two columns of the periodic table, the p orbital is assigned to columns 13-18, the d orbital begins on row 4 and encompasses the transition metals.

The coefficient (ex. 2p5) comes from what number in the orbital (s, p, d, or f) the atom/ion is located in. In this example, atom 2p5 is fluorine because it is 5th in the p orbital block.

For a future exam I recommend memorizing the periodic table linked.

1. Write the electron configuration out like normal, do not consider the charges of the atoms yet

S: 1s2, 2s2, 2p6, 3s2, 3p4

2. Then write the electron configuration considering the positive or negative charge of the atom

POSITIVE CHARGE= remove electrons from the highest orbital first

NEGATIVE CHARGE= add electrons to the highest orbital

S -2:  1s2, 2s2, 2p6, 3s2, 3p6

The original 3p4 orbital gains two electrons due to the -2 charge, making a complete orbital: 3p6

N: 1s2, 2s2, 2p3

N -3: 1s2, 2s2, 2p6 (-3 charge means adding three electrons to the highest orbital of this atom, 2p)

Mg: 1s2, 2s2, 2p6, 3s2

Mg +2: 1s2, 2s2, 2p6 (the 3s2 is gone because of the +2 charge on the ion which indicates to remove 2 electrons from the highest orbital, 3s)

Br: 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p5

Br -1: 1s2, 2s2, 2p6, 3s2, 3p6, 4s2, 3d10, 4p6 (add an electron to the highest orbital due to the -1 charge on the Br ion)

Now, compare the electron configurations for each ion. It is faster to compare the highest orbital of each ion to each other than the whole configuration itself.

Taking the highest orbital...

S -2: 3p6

N -3: 2p6

Mg +2: 2p6

Br -1: 4p6

The highest orbital in both N -3 AND Mg +2 is 2p6, signifying that these atoms have the same ground state electron configuration.

The ions that have the same ground state electron configuration are: a. N³⁻ and Mg²⁺

To determine this, we need to find the electron configuration for each ion:

1. S²⁻: Sulfur has 16 electrons, but since it gained 2 electrons, it has a total of 18 electrons. Its electron configuration is [Ne]3s²3p⁶.

2. N³⁻: Nitrogen has 7 electrons, but since it gained 3 electrons, it has a total of 10 electrons. Its electron configuration is [He]2s²2p⁶.

3. Mg²⁺: Magnesium has 12 electrons, but since it lost 2 electrons, it has a total of 10 electrons. Its electron configuration is [He]2s²2p⁶.

4. Br-: Bromine has 35 electrons, but since it gained 1 electron, it has a total of 36 electrons. Its electron configuration is [Ar]3d¹⁰4s²4p⁶.

Comparing the electron configurations, we can see that N³⁻ and Mg²⁺ have the same ground state electron configuration. Therefore, the correct answer is a. N³⁻ and Mg²⁺.

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What is the relation for entropy change for reversible process?

Answers

If the process is irreversible, the entropy change may be positive, negative, or zero, depending on the direction of heat flow.

The relation for entropy change for a reversible process is given by the equation ΔS = Qrev/T, where ΔS is the change in entropy, Qrev is the heat absorbed or released during the reversible process, and T is the temperature at which the process occurs. In a reversible process, the entropy change is positive for an increase in temperature and negative for a decrease in temperature. This equation is important in thermodynamics because it allows us to calculate the change in entropy for a reversible process and determine the maximum efficiency of a heat engine.

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Lela's teacher showed the class the image above. She explained that the image is a small crystal of salt. Lela's teacher gave the class the following information:

Some molecules bond to other molecules in a pattern. These groups of molecules are called crystals because they have a crystalline structure. They are made of molecules that join to other molecules that are the same.

Salt molecules are made of sodium and chlorine, two elements (atoms) that join together to make a salt molecule. The sodium is smaller than the chlorine.

Which of the following is TRUE?

Answers

Based on the information that "Salt molecules are made of sodium and chlorine, two elements (atoms) that join together to make a salt molecule. The sodium is smaller than the chlorine". The statement that is correct is that the small purple sphere is sodium and large green sphere is chlorine, and one salt molecule is made up of one small sphere and one large sphere. Hence, option C is correct.

Generally in chemical terms, salts are described as ionic compounds. To most of the people, salt usually refers to table salt, which is chemically sodium chloride.

Basically, Sodium chloride is formed from the ionic bonding of sodium ions and chloride ions.

Hence, option C is correct.

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Frenkel defects exist in ZrO2. For each of these defects, note how many of the following vacancies and interstitials form: (a) i Zr4+ vacancies (b) i Zr4+ interstitials (c) i 02- vacancies (d) i 02- interstitials

Answers

In ZrO2, Frenkel defects occur due to the presence of Zr4+ and O2- ions. These defects involve the displacement of cations and anions from their lattice sites. In a Frenkel defect, a cation leaves its original site and occupies an interstitial site, while an anion leaves its original site and creates a vacancy.

For each Frenkel defect, there is one vacancy and one interstitial formed. Therefore, (a) i Zr4+ vacancies and (b) i Zr4+ interstitials form one each, and (c) i O2- vacancies and (d) i O2- interstitials also form one each. These defects have significant impacts on the physical and chemical properties of materials, including ZrO2, which is used in various applications, including ceramics, fuel cells, and catalysts.

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Corrosion occurs when there is a _____ differential between two components of a system
A) current
B) voltage
C) supply
D) pH
E) carbon

Answers

The pH differential between two components of a system. Corrosion is a natural process that occurs when a material, usually a metal, starts to degrade due to the chemical reactions with its environment. The process of corrosion typically involves the flow of electrons between the two components of a system, which are at different pH levels.

This pH differential creates an electrochemical cell that drives the corrosion process. When a system has a pH differential, the more acidic component (lower pH) acts as an anode, while the more alkaline component (higher pH) acts as a cathode. This electrochemical cell causes the flow of electrons from the anode to the cathode, resulting in the oxidation of the anode and the reduction of the cathode. The oxidation process leads to the formation of corrosion products such as rust or oxide layers on the surface of the anode material. To summarize, corrosion occurs when there is a pH differential between two components of a system, leading to the formation of an electrochemical cell that drives the degradation process.

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Write the formulas for the following coordination compounds:
(i) Tetraamminediaquacobalt(III) chloride
(ii) Potassium tetracyanonickelate(II)
(iii) Tris(ethane−1,2−diamine) chromium(III) chloride
(iv) Amminebromidochloridonitrito-N-platinate(II)
(v) Dichloridobis(ethane−1,2−diamine)platinum(IV) nitrate
(vi) Iron(III) hexacyanoferrate(II)

Answers

The formulas for the following coordination compounds:

(i) Tetraamminediaquacobalt(III) chloride: [Co(NH₃)₄(H₂O)₂]Cl₃;

(ii) Potassium tetracyanonickelate(II): K₂[Ni(CN)₄];

(iii) Tris(ethane−1,2−diamine) chromium(III) chloride: [Cr(en)₃]Cl₃;

(iv) Amminebromidochloridonitrito-N-platinate(II): [Pt(NH₃)₂BrCl(NO₂)];

(v) Dichloridobis(ethane−1,2−diamine)platinum(IV) nitrate: [PtCl₂(en)₂]NO₃;

(vi) Iron(III) hexacyanoferrate(II): [Fe(H₂O)₆][Fe(CN)₆].

(i) Tetraamminediaquacobalt(III) chloride: [Co(NH₃)₄(H₂O)₂]Cl₃
The coordination sphere of the complex contains cobalt (III) ion surrounded by four ammine (NH₃) ligands and two aqua (H₂O) ligands. The counter ion, chloride (Cl⁻), is outside the coordination sphere and hence written in square brackets.

(ii) Potassium tetracyanonickelate(II): K₂[Ni(CN)₄]
The coordination sphere of the complex contains nickel (II) ion surrounded by four cyano (CN⁻) ligands. The two potassium (K⁺) ions are outside the coordination sphere and hence written separately.

(iii) Tris(ethane−1,2−diamine) chromium(III) chloride: [Cr(en)₃]Cl₃

The coordination sphere of the complex contains chromium (III) ion surrounded by three ethane-1,2-diamine (en) ligands. The counter ion, chloride (Cl⁻), is outside the coordination sphere and hence written in square brackets.

(iv) Amminebromidochloridonitrito-N-platinate(II): [Pt(NH₃)₂BrCl(NO₂)]
The coordination sphere of the complex contains platinum (II) ion surrounded by two ammine (NH₃) ligands, one bromido (Br⁻) ligand, one chlorido (Cl⁻) ligand, and one nitrito (NO₂⁻) ligand.

(v) Dichloridobis(ethane−1,2−diamine)platinum(IV) nitrate: [PtCl₂(en)₂]NO₃
The coordination sphere of the complex contains platinum (IV) ion surrounded by two ethane-1,2-diamine (en) ligands and two chlorido (Cl⁻) ligands. The counter ion, nitrate (NO₃⁻), is outside the coordination sphere and hence written in square brackets.

(vi) Iron(III) hexacyanoferrate(II): [Fe(H₂O)₆][Fe(CN)₆]
The coordination sphere of the complex contains two entities. The first entity contains iron (III) ion surrounded by six aqua (H₂O) ligands. The second entity contains hexacyanoferrate (II) ion, which is coordinated to the first entity through cyanide (CN⁻) ligands. The two entities are separated by a square bracket.

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In the chemical industry, ammonia is manufactured by the Haber process according to the following chemical equation. N2(g) + 3 H2(g) = 2 NH3(g) + heat This is an exothermic reaction. How can the yield of ammonia production be improved?

Answers

In the chemical industry, ammonia is manufactured by the Haber process according to the following chemical equation: N₂(g) + 3 H₂(g) = 2 NH₃(g) + heat. This is an exothermic reaction. To improve the yield of ammonia production, you can follow these steps:

1. Increase pressure: Increasing the pressure will shift the equilibrium towards the side with fewer moles of gas, which is the ammonia side in this case. This will increase the yield of ammonia.

2. Decrease temperature: Since the reaction is exothermic, lowering the temperature will shift the equilibrium towards the side that produces heat, which is also the ammonia side. However, this step must be balanced with the need for a reasonable reaction rate, as lower temperatures slow down the reaction rate.

3. Use a catalyst: The use of a suitable catalyst, like iron with added promoters, can help increase the rate of the reaction without affecting the position of the equilibrium. This allows for a faster production of ammonia at the desired yield.

By applying these principles, we can improve the yield of ammonia production in the chemical industry using the Haber process.

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If 3.28g of a gas occupies a volume of 6.22 liters at a pressure of 845mmHg and a temperature of 378k

A) how many moles of gas exist in the container?
B) what is the molar mass of the gas?

SHOW YOUR WORK!!!!

Answers

0.22 moles of gas exist in the container and the molar mass of the gas is 15g/mol.

The Ideal gas law is the equation of state of a hypothetical ideal gas. It is a good approximation to the behaviour of many gases under many conditions, although it has several limitations. The ideal gas equation can be written as

                                PV = nRT

where,

P = Pressure

V = Volume

T = Temperature

n = number of moles

Given,

Mass = 3.28g

Volume = 6.22 L

Temperature = 378K

Pressure = 845 mm Hg

PV = nRT

845 × 6.22 = n × 62.36 × 378

number of moles = 0.22 moles

Moles = mass / molar mass

Molar mass = mass / moles

= 3.28 / 0.22

= 15 g/mol

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purification of chromium can be achieved by electrorefining chromium from an impure chromium anode onto a pure chromium cathode in an electrolytic cell. how many hours will it take to plate 17.5 kg of chromium onto the cathode if the current passed through the cell is held constant at 34.0 a ? assume the chromium in the electrolytic solution is present as cr3 . time:

Answers

It will take approximately 948.7 hours to plate 17.5 kg of chromium onto the cathode at a constant current of 34.0 A.

The amount of electric charge required to plate a certain amount of a metal in an electrolytic cell can be calculated using Faraday's law, which states that the amount of charge (Q) required to deposit a certain amount of metal is proportional to the number of electrons transferred in the electrode reaction:

Q = nF

where n is the number of moles of metal deposited, and F is the Faraday constant (96,485 C/mol e-).

To calculate the time required to plate a certain amount of metal at a certain current, we need to know the relationship between the current, the charge, and the time. This relationship is given by:

Q = It

where I is the current, and t is the time.

Combining these equations, we get:

nF = It

Solving for t, we get:

t = nF/I

The number of moles of chromium deposited can be calculated from the mass of chromium and its molar mass. The molar mass of chromium is 52 g/mol.

Therefore, the number of moles of chromium deposited is:

n = 17.5 kg / 52 g/mol = 336.5 mol

Substituting the given values, we get:

t = (336.5 mol × 96,485 C/mol e-) / 34.0 A

Simplifying, we get:

t = 948.7 hours

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Measure the initial temperature of the water to the

nearest 0. 1°C. Record in the data table.

Initial temperature of metal=

Initial temperature water=

Final temperature of both=

Answers

The temperature changes of a metal like copper can be recorded by putting it in the water and using a thermometer. therefore, the initial temperature of metal comes to be 100°C.

The temperature of any object or a substance when it has not undergone any reaction or change and has not tolerated any physical causes like pressure, etc. is known to be its initial temperature. Initial temperature of water on putting a copper metal rod is found to be 22.4°C and that of metal is 100°C.

The temperature of any substance or an object when the reaction has finally got over is called its final temperature. In our case, the final temperature, comes out to be 21°C. Thus, there is a decrease in temperature.

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Consider a 0. 244 m aqueous solution of sodium hydroxide, naoh. (1pts) a. How many grams of naoh are dissolved in 24. 39 ml? B. How many individual hydroxide ions (OH') are found in 23. 34 ml?

Answers

There are 0.238 grams of NaOH dissolved in 24.39 mL of a 0.244 M solution. There are 3.43 × [tex]10^{21}[/tex] individual OH- ions in 23.34 mL of a 0.244 M solution of NaOH.

a. To determine the grams of NaOH dissolved in 24.39 mL of a 0.244 M solution, we can use the formula:

moles of solute = molarity × volume of solution (in liters)

First, we need to convert the volume of solution from milliliters to liters:

24.39 mL = 24.39 ÷ 1000 L = 0.02439 L

Then, we can calculate the moles of NaOH present in this volume of solution:

moles of NaOH = 0.244 M × 0.02439 L = 0.00595 moles

Finally, we can use the molar mass of NaOH to convert moles to grams:

grams of NaOH = 0.00595 moles × 40.00 g/mol = 0.238 g

B). To determine the number of individual hydroxide ions (OH-) present in 23.34 mL of a 0.244 M solution, we first need to calculate the total number of moles of NaOH present in this volume of solution:

moles of NaOH = 0.244 M × 0.02334 L = 0.00570 moles

Since NaOH dissociates in water to form one Na+ ion and one OH- ion, we know that there is the same number of moles of Na+ and OH- ions present in the solution.

Therefore, the number of individual OH- ions present in 23.34 mL of a 0.244 M solution is:

number of OH- ions = moles of OH- ions × Avogadro's number

= moles of NaOH × 1 × 6.022 × [tex]10^{23}[/tex]

= 0.00570 × 6.022 × [tex]10^{23}[/tex]

= 3.43 × [tex]10^{21}[/tex] OH- ions

A solution is a homogeneous mixture of two or more substances that are evenly distributed at the molecular or atomic level. In a solution, the solute is the substance that is being dissolved, while the solvent is the substance that does the dissolving. The concentration of the solute in a solution can vary, and it is usually expressed as the amount of solute dissolved in a certain amount of solvent.

Solutions can be classified into different categories based on their physical state and the nature of the solute and solvent. For example, a solution in which the solvent is water is called an aqueous solution, while a solution in which the solute is a gas is called a gas solution. Solutions can also be classified as dilute or concentrated based on the amount of solute present in a given amount of solvent.

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Which electron configuration represents an atom of aluminum in an excited state?

Answers

Answer:

An example of the electron configuration of aluminum in an excited state is 1s22s22p63s13p2

Answer:

The electron configuration of an aluminum atom in its ground state is 1s² 2s² 2p⁶ 3s² 3p¹.

An excited state of aluminum means that one or more of its electrons have been promoted to a higher energy level. One possible excited state electron configuration for aluminum is 1s² 2s² 2p⁶ 3s² 3p², where one of the 3p electrons has been promoted to a higher energy level.
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