Answer:
see explanation
Explanation:
When caffeine is purified, the impurities are removed, these impurities are responsible for the greater mass of pure caffeine compared to the mass of the pure sample.
The percent recovery of caffeine is frequently low because some caffeine is often left behind in the solvent during the process of recrystallization.
Secondly, since caffeine is a sublime substance, some caffeine may be lost o sublimation leading to a low percent recovery of pure caffeine.
Research Hypatia's achievements in the world
of science.
What is she most known for?
Write down three interesting facts about her
life.
Answer:
See explanation
Explanation:
Hypatia is popular for her work in mathematics. She also did some work in the area of astronomy. Her well know work in mathematics is her ideas about conic sections.
She was born the Theon of Alexandria and she was a professional mathematician in her life time.
She was the greatest mathematician of her time and she was telling leader of the Neoplatonist school of philosophy in Alexandria. By so doing, she conquered the culture of sexism in her time.
She was trained by her father in mathematics and eventually replaced him. She was the last major mathematician in the Alexandrian tradition.
A piece of metal has a mass of 0.650 kilograms, has a width of 0.136 meters, and has a length of 0.0451 meters.Part A: If the metal’s volume is 291 cm3, what is the height of the metal in centimeters? (The width & length values given above are in a different unit!)
Part B: What is the density of this piece of metal?
Answer:
height = 4.74 cm
density = 2.23 g/ cm³
Explanation:
Mass of metal = 0.650 kg (650 g)
Width = 0.136 m
Length = 0.0451 m
Volume of metal = 291 cm³
Height in cm = ?
density of metal =?
Solution:
Width = 0.136 m (0.136 m×100 cm/1m = 13.6 cm)
Length = 0.0451 m (0.0451 m×100 cm/1m = 4.51 cm)
First of all we will calculate the height:
Volume = height× width× length
291 cm³ = h × 13.6 cm × 4.51 cm
291 cm³ = h × 61.34 cm²
h = 291 cm³ / 61.34 cm²
h = 4.74 cm
Density:
d = m/v
d = 650 g/291 cm³
d = 2.23 g/ cm³
Solid diarsenic trioxide reacts with fluorine gas (F2) to produce liquid arsenic pentafluoride and oxygen gas (O2). Write the Qc for this reaction.
Answer:
QC= [O2]^3/[F2]^10
Explanation:
What is the most highly populated rotational level of Cl2 (i) 25deg C and (ii) 100 deg C? Take B=0.244cm-1.This question should not be resubmitted, it is a textbook question from the Atkins physical chemistry txtbook. 10 e.
Answer:
i
[tex]J_{m} = 20 [/tex]
ii
[tex]J_{m} = 22.5 [/tex]
Explanation:
From the question we are told that
The first temperatures is [tex]T_1 = 25^oC = 25 +273 =298 \ K[/tex]
The second temperature is [tex]T_2 = 100^oC = 100 +273 = 373 \ K[/tex]
Generally the equation for the most highly populated rotational energy level is mathematically represented as
[tex]J_{m} = [ \frac{RT}{2B}] ^{\frac{1}{2} } - \frac{1}{2}[/tex]
Here R is the gas constant with value [tex]R =8.314 \ J\cdot K^{-1} \cdot mol^{-1}[/tex]
Also
B is given as [tex]B=\ 0.244 \ cm^{-1}[/tex]
Generally the energy require per mole to move 1 cm is 12 J /mole
So [tex]0.244 \ cm^{-1}[/tex] will require x J/mole
[tex]x = 0.244 * 12[/tex]
=> [tex]x = 2.928 \ J/mol [/tex]
So at the first temperature
[tex]J_{m} = [ \frac{8.314 * 298 }{2* 2.928 }] ^{\frac{1}{2} } - 0.5 [/tex]
=> [tex]J_{m} = 20 [/tex]
So at the second temperature
[tex]J_{m} = [ \frac{8.314 * 373 }{2* 2.928 }] ^{\frac{1}{2} } - 0.5 [/tex]
=> [tex]J_{m} = 22.5 [/tex]
Which of the following elements has the largest atomic radius? Bromine, Barium, Magnsium, Zinc
Answer:
Atomic radii vary in a predictable way across the periodic table. As can be seen in the figures below, the atomic radius increases from top to bottom in a group, and decreases from left to right across a period. Thus, helium is the smallest element, and francium is the largest.
Explanation:
An increase in temperature results in A) a decrease in the required activation energy while the reaction rate remains constant. B) an increase in reaction rate due to a decrease in the kinetic energy of the reactants. C) an increase in the rate of reaction because reactant molecules collide with greater energy. D) an increase in both the reaction rate and activation energy due to increased kinetic energy.
Answer:
C) an increase in rate of reaction because reactant molecules collide with greater energy
Explanation:
Temperature is one of the factors that affect the rate of a reaction. The rate of a reaction increases with an increase in temperature and vice versa. When the temperature of a reaction increases, the kinetic energy of the reactant molecules increases causing them to react at a faster rate.
The reactant molecules respond to an increase in temperature by colliding at a faster rate due to an increased kinetic energy between the reactant molecules.
If the earth was a guava fruit, the space where the seeds are would be the core/mantle
How many carbon atoms are in vitamin c?
Answer:
molecules can be much bigger. one molecule of vitamin c is made up of 20 atoms (6 carbons, 8 hydrogens, and 6 oxygens
9 What 11 letter word describes the chemical balance within an organism?
___________________________________
10 What 7 letter word describes the waterproof outer layer for soft-bodies creatures?
___________________________________
11 What word starting with the letter "C" is the liquid material found within cells?
___________________________________
12 What word starting with the letter "C" is a process of organizing things into groups scientifically?
___________________________________
Answer:
9.) Homeostasis
10.) Epidermis
11.) Cytoplasim
12.) Classification
What happens to a person's weight on smaller and larger planets?
Answer: The size actually does not matter. But planets with smaller mass will have less gravity decreasing their weight. Other for larger mass planets, more mass is more gravity which is also more weight.
Explanation:
Please choose the best description, or definition for Principle of Fossil Correlation
Answer:
states that rock layers with the same unique groupings of fossils are of the same geologic age.
Explanation:
The principle of fossil correlation states that the presence of similar fossils of dead organisms in rock layers indicates that the organisms under investigation must have existed around the same geologic time. This principle can be used in dating the periods when the organism being studied lived.
The geological age system follows a chronological format in tracking the age of an item under study by grouping the time periods that organisms lived into strata.
if u trust urself do it! (not sponsored by nike)
Which is one factor that contributes to the formation of polar, temperate, and tropical zones?
the angle of the Sun’s rays
the direction of seasonal winds
the presence of prevailing winds
the movement of wind near a mountain
Answer: A) The angle of the Sun's rays!
Answer:
A) The angle of the Sun's rays!
Explanation:
If 25.98 mL of 0.1180 M KOH reacts with 52.50 mL of CH3COOH solution, what is the molarity of the acid solution?
Answer:
Explanation:
We shall use the formula S₁V₁ = S₂V₂
S₁ = .1180 M , V₁ = 25.98 mL
S₂ = ? , V₂ = 52.50 mL
.1180 M x 25.98 = 52.50 x S₂
S₂ = .0584 M
Molarity of the acid solution = .0584 M .
The concentration of the acid solution is 0.058 M.
The equation of the reaction is;
CH3COOH(aq) + KOH(aq) -----> CH3COOK(aq) + H2O(l)
The following are known;
Concentration of base CB = 0.1180 M
Volume of base VB = 25.98 mL
Concentration of acid CA = ?
Volume of acid VA = 52.50 mL
Number of moles of acid NA = 1
Number of moles of base NB = 1
Using;
CAVA/CBVB =NA/NB
CAVANB = CBVBNA
CA= CBVBNA/VANB
CA = 0.1180 M × 25.98 mL × 1/52.50 mL × 1
CA = 0.058 M
Learn more: https://brainly.com/question/24381583
What is the mass in grams of 2.5 moles of Al?
Answer:
One mole of Al weighs 27g.
2.5 moles of Al weigh 67.5g.
In the laboratory you dissolve 18.7 g of copper(II) bromide in a volumetric flask and add water to a total volume of 375mL.
Required:
a. What is the molarity of the solution?
b. What is the concentration of the copper(II) cation?
c. What is the concentration of the acetate anion?
Answer:
a) - 0.2 M
b) - 0.2 M
c)- 0
Explanation:
The chemical formula of copper (II) bromide is CuBr₂. Its molar mass (MM) is calculated as follows:
MM(CuBr₂)= MM(Cu) + (2 x MM(Br) = 63.5 g/mol + (2 x 80 g/mol)= 223.5 g/mol
a). Molarity = moles CuBr₂/1 L solution
moles CuBr₂ = mass/MM = 18.7 g x 1 mol/223.5 g = 0.084 mol
Volume in L = 375 mL x 1 L/1000 mL = 0.375 L
M = 0.084 mol/(0.375 L) = 0.223 M ≅ 0.2 M
b). When is added to water, CuBr₂ dissociates into ions as follows:
CuBr₂ ⇒ Cu²⁺ + 2 Br⁻
We have 1 mol Cu²⁺ (copper (II) cation) per mol of CuBr₂. Thus, the concentration of copper (II) cation is:
0.2 mol CuBr₂ x 1 mol Cu²⁺/mol CuBr₂ = 0.2 M
c). The concentration of acetate anion is 0. There is no acetate anion in the solution (the anion from CuBr₂ is bromide Br⁻).
How does an anion form?
A. An anion forms when a stable atom loses one or more neutrons.
B. An anion forms when a stable atom loses one or more protons.
C. An anion forms when a stable atom gains one or more electrons.
D. An anion forms when a stable atom loses one or more electrons.
PLEASE HELP! WILL DO BRAINLIEST! What do scientists call all of the compounds that contain carbon and are found in living things?
organic
inorganic
acidic
nonacidic
Answer:
acidic because of electrical issues and the body of electrical equipment
Which element will gain three electrons to form an anion?
A. aluminum
B. chromium
C. iron
D. nitrogen
Answer:
D represents the element nitrogen which will gain three valence electrons forming a 3 ion.
Answer:
answer is
Explanation:
D
The amount of UVA radiation hitting a surface at sea level in a lightly clouded day is about 70W/m2. About half of that can be absorbed by the skin. A typical carbon- carbon bond requires 348 kJ/mol to break. A person lies on the beach for about 1 hour without sunscreen (i.e. fully exposed to UVA radiation). Estimate the number of C-C bonds broken in this person’s back (about 0.18 m2) over that period. Assume that the average wavelength of UVA is 335 nm.
Answer:
Explanation:
energy of solar radiation = 70 W / m²
energy absorbed in 1 hour by an area of .18 m²
= 70 x .5 x .18 x 60 x 60 J
= 22.68 x 10³ J
bond energy of i mole bond = 348 x 10³ J
bond energy of 6.02 x 10²³ bonds = 348 x 10³ J
bond energy of one bond = 57.8 x 10⁻²⁰ J
No of bonds broken by energy 22.68 x 10³
= 22.68 x 10³ / 57.8 x 10⁻²⁰
= .3923 x 10²³
= 39.23 x 10²⁰ .
which angles are right
Answer:
a right is 90 degrees
HELP FAST PLZ!!!!! Which phase change allows a substance to transform from a liquid to a
gas?
melting
Ofreezing
O ionization
condensation
deionization
O
evaporation
sublimation
Answer:evaporation
Explanation:
Answer:
Pretty sure its evaporation, if its not I'm very sorry.
what is a family in a periodic table?
Answer:
A family is a vertical column .
The elements in a family have similar chemical properties.
The wood in my house is crumbling. *
Problem
Hypothesis
Law
Theory
Answer:
Problem
Explanation:
The given statement is a problem. It states the problem that the house of the speaker has been undergoing with. This problem gives rise to the Hypothesis in which the 'why' question is asked. The reason of the crumbling of the wood is stated in the hypothesis. Any reason placed of the happening of the event is stated to be hypothesis.
1.
Light near the middle of the ultraviolet region of the electromagnetic spectrum
has a frequency of 2.73 X 1016 s-1
a.
What is the wavelength of this radiation in meters (m)?
b.
What is the energy associated with this radiation in kcal?
Explanation:
Given that,
The frequency of electromagnetic spectrum is [tex]2.73\times 10^{16}\ Hz[/tex]
(A) Let the wavelength of this radiation is [tex]\lambda[/tex]. We know that,
[tex]c=f\lambda\\\\\lambda=\dfrac{c}{f}\\\\\lambda=\dfrac{3\times 10^8}{2.73\times 10^{16}}\\\\\lambda=1.09\times 10^{-8}\ m[/tex]
So, the wavelength of this radiation is [tex]1.09\times 10^{-8}\ m[/tex].
(B) Let E is the energy associated with this radiation. Energy of an electromagnetic radiation is given by :
[tex]E=hf[/tex]
h is Planck's constant
[tex]E=6.63\times 10^{-34}\times 2.73\times 10^{16}\\\\E=1.8\times 10^{-17}\ J[/tex]
1 kcal = 4184 J
It means,
[tex]1.8\times 10^{-17}\ J=\dfrac{1}{4184}\times 1.8\times 10^{-17}\\\\=4.3\times 10^{-21}\ \text{kcal}[/tex]
Hence, this is the required solution.
On the graph, which shows the potential energy curve of two N atoms, carefully sketch a curve that corresponds to the potential energy of two O atoms versus the distance between their nuclei.
Answer:
Explanation:
We are to carefully sketch a curve that relates to the potential energy of two O atoms versus the distance between their nuclei.
From the diagram, O2 have higher potential energy than the N2 molecule. Because on the periodic table, the atomic size increases from left to right on across the period, thus O2 posses a larger atomic size than N2 atom.
Therefore, the bond length formation between the two O atoms will be larger compared to that of the two N atoms.
Science...............
Rahul and Manav each were given a mixture of iron filings and sulphur powder. Rahul heated the mixture strongly and a new substance was formed. Write three points of difference between the two.Required to answer.
Answer:
sure
Explanation:
The substance formed after heating the mixture of that of Rahul is caleed a compound. Whereas, Manav's mixture still remains in its current stae that is a heterogeneous mixture.
The compound formed is in black in color whereas the mixture is a mix of brownish-red and yellow.
The compound is a homogeneous mixture whereas the mixture is a heterogenous mixture because of its uneven distribution.
Which of the following best describes the structure of a nucleic acid?
a. Carbon ring(s)
b. Globular or fibrous
c. Single or double helix
d. Hydrocarbon(s)
A bicycle rider is applying a force of 20 N while heading south against a wind blowing from the south with a force of 5 N
Answer:
the bike will go down 5 N
plz help on both I will mark brainest and explain how you got it
Answer:
as much as i can see i think it goes like this?:
1.H202--> H20+02
Answer is 2,2,1 bc
1.when you add 2 to H202 its 2H202 so H is 4 and O is 4,
2.when you add 2 to H20 its 2H20 so H is 4 and O is 2 (so H is done and good on both sides we have 4 H)
3. and then when you add 1 to O2 its still O2 you dont need to add anything bz when you add the 2O from 2H2O with O2 its 4 O so everything's good (i explained it a bit messy so you can message me if you got questions)
2. Ag20->Ag+ O2
answer is 2,4,1
1.when you add 2 to Ag2O2 it becomes 2Ag2O (so Ag is 4 and O is 2)
2. you add 4 to Ag bc on the left side when you added 2 Ag became 4 so now its equal on both sides (they're both 4)
3.you add 1 (basically dont add anything bc you dont write 1 just leave it as O2) bc on left side you got O2 and the same on right side (if you got questions message me:))