Answer:
The wood sample has an age of approximately 22800 years.
Explanation:
The Becquerel ([tex]Bq[/tex]) is a SI unit which describes radioactive activity related to decay of radioactive isotopes, which is equivalent to [tex]\frac{1}{s}[/tex]. The decay of radioactive isotope is described by the following ordinary differential equation:
[tex]\frac{dN}{dt} = -\frac{N}{\tau}[/tex] (Eq. 1)
Where:
[tex]\frac{dN}{dt}[/tex] - Disintegration rate, measured in [tex]\frac{1}{s}[/tex].
[tex]N[/tex] - Amount of remaining radioactive nuclei, dimensionless.
[tex]\tau[/tex] - Time constant, measured in seconds.
By integration the solution of this differential equation is obtained:
[tex]\int {\frac{dN}{N} } = -\frac{t}{\tau}\int dt[/tex]
[tex]\ln N = -\frac{t}{\tau} + C[/tex]
[tex]N(t) = N_{o}\cdot e^{-\frac{t}{\tau} }[/tex] (Eq. 2)
Let [tex]N_{1}[/tex] and [tex]N_{2}[/tex] different disintegration rates for Carbon-14 samples, so that:
[tex]N_{1} = N_{o} \cdot e^{-\frac{t_{1}}{\tau} }[/tex] (Eq. 3)
[tex]N_{2} = N_{o}\cdot e^{-\frac{t_{2}}{\tau} }[/tex] (Eq. 4)
If we divide (Eq. 4) by (Eq. 3), then:
[tex]\frac{N_{2}}{N_{1}} = \frac{N_{o}\cdot e^{-\frac{t_{2}}{\tau} }}{N_{o}\cdot e^{-\frac{t_{1}}{\tau} }}[/tex]
[tex]\frac{N_{2}}{N_{1}} = e^{-\frac{1}{\tau}\cdot (t_{2}-t_{1}) }[/tex] (Eq. 5)
If [tex]\Delta t = t_{2}-t_{1}[/tex], we proceed to clear that variable:
[tex]\ln \frac{N_{2}}{N_{1}} = -\frac{1}{\tau}\cdot \Delta t[/tex]
[tex]\Delta t = -\tau\cdot \ln \frac{N_{2}}{N_{1}}[/tex] (Eq. 6)
Time constant is also a function of half-life ([tex]t_{1/2}[/tex]), measured in seconds:
[tex]\tau = \frac{t_{1/2}}{\ln 2}[/tex]
If [tex]t_{1/2} = 1.798\times 10^{11}\,s[/tex], [tex]N_{1} = 14\,\frac{1}{s}[/tex] and [tex]N_{2} = 0.875\,\frac{1}{s}[/tex], the age of the wood sample is:
[tex]\tau = \frac{1.798\times 10^{11}\,s}{\ln 2}[/tex]
[tex]\tau = 2.594\times 10^{11}\,s[/tex]
[tex]\Delta t = -(2.594\times 10^{11}\,s)\cdot \ln \left(\frac{0.875\,\frac{1}{s} }{14\,\frac{1}{s} } \right)[/tex]
[tex]\Delta t \approx 7.192\times 10^{11}\,s[/tex]
[tex]\Delta t \approx 22805.682\,yr[/tex]
The wood sample has an age of approximately 22800 years.
ou are given a solution containing a pair of enantiomers (A and B). Careful measurements show that the solution contains 98% A and 2% B. What is the ee of this solution
Complete Question
You are given a solution containing a pair of enantiomers (A and B). Careful measurements show that the solution contains 98% A and 2% B. What is the enantiomeric excess?
Answer:
The value is [tex]k = 96 %[/tex]
Explanation:
From the question we are told that
The percentage of enantiomer A is A = 98%
The percentage of enantiomer B is B = 2%
Generally the enantiomeric excess is mathematically represented as
[tex]k = \frac{A -B}{A+B} * 100[/tex]
=> [tex]k = \frac{98 -2}{98+2} * 100[/tex]
=> [tex]k = 96 %[/tex]
What is the momentum of a 1kg ball moving at 5m/s?
Answer:
5Ns
momentum= mass *velocity
=1*5
=5Ns
How many moles of each substance is produced when 7 moles of ammonium carbonate decompose?
(NH4)2CO3(s) ⟶ NH3(g) + CO2(g) + H2O(g)
Answer:
1. 14 moles of NH3 were produced.
2. 7 moles of CO2 were produced.
3. 7 moles of H2O were produced.
Explanation:
We'll begin by writing a balanced equation for the decomposition of ammonium carbonate, (NH4)2CO3.
This is illustrated below:
(NH4)2CO3(s) —> NH3(g) + CO2(g) + H2O(g)
There are 2 atoms of N on the left side and 1 atom on the right side. It can be balance by putting 2 in front of NH3 as shown below:
(NH4)2CO3(s) —> 2NH3(g) + CO2(g) + H2O(g)
Now the equation is balanced.
From the balanced equation above,
1 mole of (NH4)2CO3 decompose to produce 2 moles of NH3, 1 mole of CO2 and 1 mole of H2O.
1. Determination of the number of mole of NH3 produced.
From the balanced equation above,
1 mole of (NH4)2CO3 decompose to produce 2 moles of NH3.
Therefore, 7 moles of (NH4)2CO3 will decompose to produce = 7 × 2 = 14 moles of NH3.
Therefore, 14 moles of NH3 were produced.
2. Determination of the number of mole CO2 produced.
From the balanced equation above,
1 mole of (NH4)2CO3 decompose to produce 1 mole of CO2.
Therefore, 7 moles of (NH4)2CO3 will also decompose to produce 7 moles of CO2.
Therefore, 7 moles of CO2 were produced.
3. Determination of the number of mole of H2O produced.
From the balanced equation above,
1 mole of (NH4)2CO3 decompose to produce 1 mole of H2O.
Therefore, 7 moles of (NH4)2CO3 will also decompose to produce 7 moles of H2O.
Therefore, 7 moles of H2O were produced.
What does this image represent?
a) alcohol group
b) carbonyl group
c) ether group
d) hydroxyl group
Explanation:
It represent Alcohol group (—OH)
What is the value of E0 for the spontaneous reaction resulting from a suitable combination of these half reactions?
Standard Potentials E0
Fe2+ --> Fe3+ + e- -0.77 V
2Hg --> Hg2+ + 2e- -0.79 V
a. +0.02 V.
b. +0.36 V.
c. -1.56 V.
d. -0.02 V.
e. +1.56 V.
Answer:
+0.02 V
Explanation:
For the reaction to be spontaneous, iron must be the cathode and Mercury the anode
Given that the standard cell potential is obtained from;
E°=E° cathode - E° anode
Since;
E° cathode = -0.77V
E° anode = 0.79 V
E°cell = -0.77 -(-0.79)
E°cell = +0.02 V
3. Which of the following molecules would want except to have a nonpolar covalent bond
Answer:
polar bonds are caused by different kind of atoms, because almost every atoms have different powers to attract electrons.
the answer will be the two same atoms, F2
Which condition produces an anion?
A. more neutrons than electrons
B. more protons than electrons
C. more electrons than neutrons
D. more electrons than protons
Convert
12 x 1025 kg/mL to fg/cm3
Answer:
[tex]1.2x10^{38}\frac{fg}{cm^3}[/tex]
Explanation:
Hello there!
In this case, for such unit conversion we need to realize that 1 kg is equal to 1000 g, 1 g is equal to 1x10⁹ and 1 mL equals 1 cm³, therefore we apply:
[tex]12x10^{25}kg*\frac{1000g}{1kg} *\frac{1x10^9fg}{1g} *\frac{1mL}{1cm^3} \\\\1.2x10^{38}\frac{fg}{cm^3}[/tex]
Best regards!
Consider the diagram below.
What does C represent?
A) enthalpy of reaction
B) activation energy
C) activated complex
D) energy of the reactants
Answer:
A) enthalpy of reaction
Explanation:
The region C signifies the enthalpy of reaction.
This diagram is the energy profile of an endothermic reaction. In such reaction, heat is absorbed from the surrounding. At the end of the reaction, the heat of product is lesser than that of the reactants.
Enthalpy changes are heat changes accompanying a physical and chemical change. An enthalpy is the difference between the sum of the heat contents of products and sum of the heat contents of reactants.it is indeed A) enthalpy of reaction
which of the following determines an object’s ability to float in water?
a. how much the object weighs
b. what the mass of the object is
c. how dense the object is
d. the volume of the object
When methylcyclobutane is treated with chlorine gas and heated, the total number of monochlorinated products, including stereoisomers, is
Answer:
5
Explanation:
The image attached shows the different monochlorination products obtained when chlorine gas is heated with methylcyclobutane.
We must keep in mind that the reaction occurs by free radical mechanism as shown in the image attached. The proportion in which the products are formed depends on the stability of the free radical intermediate leading to that particular product.
Image credit: askiitians
if you wanted to measure in irregular object's volume, which device would you use?
Answer:
a beaker
Explanation:
Please help! I'm confused on a few of these, 100 points!
A tank at is filled with of dinitrogen difluoride gas and of chlorine pentafluoride gas. You can assume both gases behave as ideal gases under these conditions. Calculate the mole fraction and partial pressure of each gas, and the total pressure in the tank. Be sure your answers have the correct number of significant digits.
The question is incomplete, the complete question is;
A 8.00 L tank at 2.64 °C is filled with 9.82 g of chlorine pentafluoride gas and 10.1 g of dinitrogen difluoride gas. You can assume both gases behave as ideal gases under these conditions. Calculate the mole fraction and partial pressure of each gas, and the total pressure in the tank. Be sure your answers have the correct number of significant digits.
Answer:
See explanation for details
Explanation:
Number of moles of N2F2 = mass/ molar mass
Molar mass of N2F2 = 66 g/mol
Number of moles = 10.1 g/66 = 0.15 moles
Number of moles of ClF5 = 9.82 g/130 g/mol= 0.08 moles
Molar mass of ClF5= 130g/mol
Total number of moles = 0.15 moles + 0.08 moles = 0.23 moles
Given that;
T= 2.64 °C + 273 = 275.64 K
n= 0.23 moles
R= 0.082 Latmmol-1K-1
V= 8.00 L
P= ??
From;
PV =nRT
P= nRT/V
P= 0.23 ×0.082 × 275.64/8.00
P= 0.65 atm
Mole fraction of N2F2= 0.15/0.23 = 0.65
Partial pressure = mole fraction × total pressure = 0.65 × 0.65 = 0.42 atm
Mole fraction of ClF5 = 0.08/0.23 = 0.35
Partial pressure of ClF5 = mole fraction × total pressure = 0.35 × 0.65 = 0.22 atm
he concentration of H2S in a saturated aqueous solution at room temperature is approximately 0.1 M. Ka1=8.9x10-8 Ka2=1.0x10-19 Calculate the pH of the solution in 2 sig figs
Answer:
PH = 4.0
Explanation:
We are given;
Ka1 = 8.9 × 10^(-8)
Ka2 = 1.0 × 10^(-19)
From the 2 values of K given above, we can see that Ka2 is far smaller than Ka1.
Thus, Positive hydrogen ion (H+) will be majorly formed from first dissociation which is Ka1.
Now, the breakdown of the H2S solution is;
H2S⇌[H+] + [HS−]
Thus;
Ka1 = [[H+] × [HS2^(-)]]/(H2S)
HS2^(-) also has a positive hydrogen ion.
Thus, we can rewrite as;
Ka1 = [[H+] × [H+]]/(H2S)
Ka1 = (H+)²/(H2S)
Concentration of H2S is given as 0.1M. Thus;
8.9 × 10^(-8) = (H+)²/0.1
(H+)² = 0.1 × 8.9 × 10^(-8)
(H+) = √(0.1 × 8.9 × 10^(-8))
(H+) = 0.00009433981
Now, PH is gotten from;
PH = -log (H+)
Thus;
PH = -log 0.00009433981
PH ≈ 4.0
Two fruit flies that are heterozygous for body color and eye color are crossed. Brown body color is dominant to black body color. Red eye color is dominant to brown eye color.
Determine the genotypes of offspring 1-8.
1
2
3
4
5
6
7
8
A 4-column table has 4 rows. The labels of the columns are Upper B Upper E, Upper B e, b Upper E, b e. The labels of the rows are Upper B Upper E, Upper B e, b Upper E, Upper B b Upper E e. The first column has entries 1, Upper B Upper B Upper E e, 4, Upper B b Upper E e. The second column has entries Upper B Upper B Upper E e, 3, Upper B b Upper E e, 7. The third column has entries Upper B b Upper E Upper E, Upper B b Upper E e, 5, b b Upper E e. The fourth column has entries 2,Upper B b e e, 6, 8.
Answer:
the answer is simple
Explanation:
jnnn B upper up of the eye color
Answer:
1. BBEE
2. BbEe
3. BBee
4. BbEE
5. bbEE
6. bbEe
7. Bbee
8.bbee
Which of the following particles combine to form molecules?
Compounds
Protons
Electrons
Atoms
Answer: i think its protons and electrons but it also might just be atoms because protons and electrons make atoms when there are also neutrons
Explanation:
3. Does matter increase in
mass when mixed with
another substance?
a Yes
b. No
Answer:
b. No
Explanation:
The question above is related to "The Law of Conservation of Mass." This law states that mass is neither created nor can it be destroyed. Even if a particular matter will be mixed with another substance or it undergoes chemical reaction, the mass of the matter will remain the same. Even with a change in phase, the mass of the matter will remain the same.
The density of wind-packed snow is estimated to be 0.35 g/cm^3. A flat roof that is 35 by 43 feet has 28 inches of snow on it. How many pounds of snow are on the roof?
Answer:
There are 76728.2 pounds of snow on the roof
Explanation:
To determine how many pounds of snow are on the roof,
First we will determine the mass of the snow in grams.
From the question,
Density of snow = 0.35 g/cm³
From
Density = Mass / Volume
To determine the mass, we will first find the volume.
From the question, a flat roof that is 35 by 43 feet has 28 inches of snow on it, that is, the height of the snow on the roof is 28 inches.
Area of the roof = 35 ft × 43 ft = 1505 ft²
Volume of the snow = Area of the roof × Height of the snow
Height of the snow = 28 inches
12 inches = 1 foot
∴ 28 inches = 28/12 feet = 2.3333 ft
Hence,
Volume of the snow = 1505 ft² × 2.3333 ft = 3511.62 ft³
Volume of the snow = 3511.62 ft³
This is the volume of the snow in cubic feet
Now, we will convert cubic feet (ft³) to cubic centimeter (cm³)
1 ft = 30.48 cm
and 1 ft³ = 30.48³ cm³ = 28316.84659 cm³.
If 1 ft³ = 28316.84659 cm³
∴ 3511.62 ft³ will be 3511.62 × 28316.84659 cm³ = 99438004.83 cm³
Hence, Volume of snow = 99438004.83 cm³
Now, we can determine mass of snow in grams
From
Density = Mass / Volume
Mass = Density × Volume
Mass = 0.35 g/cm³ × 99438004.83 cm³
Mass = 34803301.69 g
Now, we will convert the mass from grams to pounds
1 pound = 453.592 grams
If 453.592 grams = 1 pound
Then, 34803301.69 g will be 34803301.69 / 453.592 pounds = 76728.2 pounds
Hence, there are 76728.2 pounds of snow on the roof.
Which is one way that minerals crystallize from materials dissolved in water?
from the air
from solutions that evaporate
from hot water solutions when water boils
from the soil
Answer:
the second answer its science behind it
Answer:
b
Explanation:
what is the relationship between the atomic number and the melting and boiling point
Answer:
As the atomic number of elements increases, the melting point increases because there are more electrons around the nucleus, which creates a stronger negatively-charged force. With stronger forces, the melting point rises. 3. Non-metals usually have low melting points.
Explanation:
The melting point rises as the atomic number of elements increases because there are more electrons surrounding the nucleus, creating a stronger negatively charged force. The melting point rises as the forces become stronger.
What is nucleus?The nucleus is made up of protons, which are positively charged, and neutrons, which are electrically neutral. Quarks are particles that make up protons and neutrons. The nucleus (plural, nuclei) is a positively charged region in the atom's center. It is made up of two types of subatomic particles that are tightly packed together. Protons, which have a positive electric charge, and neutrons, which have a neutral electric charge, are the particles. The nucleus is the most important component of the cell (plural: nuclei). It is derived from a Latin word that means "nut kernel." Definition of Nucleus: A nucleus is a double-membraned eukaryotic cell organelle that contains genetic material.To learn more about nucleus, refer to:
https://brainly.com/question/14110259
#SPJ2
Calculate the pH of a 0.02 M solution of ascorbic acid ( K a1 = 7.9 × 10 –5; K a2 is 1.6 × 10 –12).
a.
2.9
b.
8.2
c.
11.8
d.
11.1
e.
5.8
Answer:
C
Explanation:
The first energy level which has p orbitals to fill is ___
1
2
3
4
Answer:
2
Explanation:
The Aufbau sequence of increasing energy levels is 1s,2s,2p,3s,3p,4s,3d and so on....
Hope this helps! :D
Someone plz hello me ASAP it would be appreciated on question 7 btw
Answer:
Kinetic Energy is the correct Answer.
Explanation:
At the highest point on the roller coaster (assuming it has no velocity), the object has a maximum quantity of gravitational potential energy. As the object begins moving down to the bottom, its gravitational potential energy begins to decrease and the Kinetic Energy starts to increase.
1.191 mol N2O3 is put into a 2.00 L flask at 25°C where it decomposes into NO2(g) and NO(g). What is the equilibrium constant (to 4 decimal places) if the reaction mixture contains 0.300 mol NO2 at equilibrium?
Answer:
K = 0.0505
Explanation:
Based on the equilibrium:
N2O3 ⇄ NO2 + NO
K, equilibrium constant, is defined as:
K = [NO2] [NO] / [N2O3]
Where [] are the equilibrium concentration of each species in the mixture.
The initial molarity of N2O3 is:
1.191mol / 2.00L = 0.5955M
In equilibrium, 0.5955M of N2O3 reacts producing X Molar of NO2 and X Molar of NO:
[N2O3] = 0.5955M - X
[NO2] = X
[NO] = X
As equilibrium concentration of NO2 is 0.300mol/2.00L = 0.15M; X = 0.15M:
[N2O3] = 0.5955M - 0.15M = 0.4455M
[NO2] = 0.15M
[NO] = 0.15M
And K is:
K = [0.15M] [0.15M] / [0.4455M]
K = 0.0505
PLS PLS PLS PLS PLS PLS PLS help ASAP!!!!! Scientists call all of the compounds that contain carbon and are found in living things Organic because ________.
WILL DO BRAINLIEST!
2. Determine the possible traits of the calves of : Da red (RR) bull is mated with a red (RR) cow 1 a red * (RR) bullis mated with a white (WW) Cow 2 Da roan * (RW) is mated with a red(RR)Cow 3 3. Illustrate your answers using a Punnett square. 4. Write your answers on the paper.
explain the reason each step of the separation is performed with three portions of the solvent rather than with a single poriton of solvent
Answer:
Several extractions is more effective than a single extraction.
Explanation:
When extraction is carried out multiple times, for instance, in this case, the extraction was carried out with three portions of the solvent rather than with just a single portion of the solvent, the amount of material left in the residue will be lower, because the extraction is more complete.
Several extractions with smaller volumes of solvent are more effective than a single extraction with a large volume of solvent.
For a water in equilibrium with the atmosphere, a pH of 2.0, and a total soluble iron concentration of 1 mg/L, calculate the concentrations of Fe2+(aq) and Fe3+(aq).
Answer:
Fe^2+(aq) = 4.51 × 10^-11 M
Fe3+(aq) = 1.79 × 10^5 M.
Explanation:
So, the first thing to do is to to write out the chemical reaction showing the ionic reaction of the chemical species present in the chemical reaction;
4Fe^2+ (aq) + O2(g) + 4H^+ <---------------------------> 4Fe^3+(aq) + 2H2O(l).
The next thing to do is to determine or calculate for G° and the equilibrium constant,kc. Thus, the value of G° = 4(-4.6) + 2(-237.18) - {4(-78.87)} = -177.28 kJ/mol.
Therefore, the equilibrium constant = e^-∆G°/RT = 1.19 × 10^31.
Therefore the value for Fe^2+ and Fe^3+ can be determine as;
NB=> Recall that [Fe^3+]/[Fe^2+] = kc [(Po2) (H^+)^4]^1/4.
Also, 1/ 55850 = 1.79 × 10^-5 M.
[Fe^2+] + [Fe^3+] = 1.79 × 10^-5. -------(1).
Therefore, [Fe^3+]/[Fe^2+] = kc [(Po2) (H^+)^4]^1/4. = [Fe^3+]/[Fe^2+] = [ 1.19 × 10^31 × 0.2095 × (10^2)^2] ^1/4 = 3.97 × 10^5.
Therefore, [Fe^3+]/[Fe^2+] = 3.97 × 10^5.
[Fe^3+] = 3.97 × 10^5[Fe^2+].
Hence, using the equation (1) above we can determine the value of the species.
[Fe^2+] + [Fe^3+] = 1.79 × 10^-5
[Fe^2+] + [Fe^2+] = 1.79 × 10^-5.
[Fe^2+] + 3.97 × 10^5[Fe^2+] = 1.79 × 10^-5.
[Fe^2+] = 4.51 × 10^-11 M.
Therefore, we will have [Fe^3+]/[Fe^2+] = 3.97 × 10^5.
Thus, [Fe^3+] = [Fe^2+] × 3.97 × 10^5. = 1.79 × 10^5 M.
Two elements in the same period have the same number of _____ _____ in their electron clouds.
Answer:
outer electrons
Explanation:
Answer:
Energy levels
Explanation: