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Tju [1.3M]
3 years ago
5

The atomic mass and abundance of Cr-50 is 49.946 amu and 4.3%. The atomic mass and abundance of Cr-52 is 51.941 amu and 83.8%. T

he atomic mass and abundance of Cr-53 is 52.941 amu and 9.5%. The atomic mass and abundance of Cr-54 is 53.939 amu and 2.4%. Which is the average atomic mass of chromium?
A.51.94 amu
B.52.00 amu
C.52.19 amu
D.53.94 amu
Chemistry
1 answer:
Leviafan [203]3 years ago
3 0

Answer:

52.00 AMU

Explanation:

(49.946 * 0.043) + (51.941 * 0.838) + (52.941 * 0.095) + (53.939 * 0.024) = 51.998

Make sure to round, 52.00 AMU.

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Determine if the following is a compound , Element or Mixture
Katarina [22]

Compound is a group of same molecules, Element is a group of same atoms and mixture is combination of two or more pure substances.

What are Molecules ?

Molecules are the combination of two or more different atoms combine in a fixed ratio.

Molecules can be independently founded.

Atoms are always founded in combined state and does not occurs independently except rare earth elements which belongs to 18th group of periodic table.

Chemicals are taken in compound state But they undergo chemical reaction individually in molecular level.

Hence, Compound is a group of same molecules, Element is a group of same atoms and mixture is combination of two or more pure substances.

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8 0
2 years ago
The vapor pressure of pure water at 250C is 23.77 torr. What is the vapor pressure of water above a solution that is 1.500 m glu
Olegator [25]

Answer:

Vapor pressure of water = 23.14torr

Explanation:

When you made a solution, vapor pressure decreases following Raoult's law:

P_{solution} = X_{solvent} P_{solvent}

<em>Where P is vapor pressure and X mole fraction</em>

As vapor pressure of water is 23.77torr we must find the mole fraction of water knowing the solution is 1.500m glucose (That is 1.500 moles of glucose per kg of water = 1000g of water).

1000g of H₂O are, in moles (Molar mass: 18.02g/mol):

1000g H₂O ₓ (1mole / 18.02g) = 55.5 moles of H₂O.

As we know now the solution contains 55.5 moles of water and 1.5 moles of glucose. Thus, mole fraction of water (Solvent) is:

X_{H_2O} = \frac{55.5molesH_2O}{55.5molesH_2O + 1.5 molesGlucose} = 0.9737

Replacing in Raoult's law, pressure of water above the solution is:

P_{solution} = X_{solvent} P_{solvent}

P_{solution} = 0.9737*23.77torr

<h3>Vapor pressure of water = 23.14torr</h3>
7 0
3 years ago
1. A student needs to make 80mL of a 4.5 x 10^-3 M solution of H_3PO_4 (mm = 98) from solid. Describe how the student would do t
slamgirl [31]

Answer:

1. 35 mg of H₃PO₄

2. 27 mol AlF₃; 82 mol F⁻

3. 300 mL of stock solution.

Explanation:

1. Preparing a solution of known molar concentration

Data:

V = 80 mL

c = 4.5 × 10⁻³ mol·L⁻¹

Calculations:

(a) Moles of H₃PO₄

Molar concentration = moles of solute/litres of solution

c = n/V

n = Vc = 0.080L × (4.5 × 10⁻³ mol/1 L) = 3.60 × 10⁻⁴ mol

(b) Mass of H₃PO₄  

moles = mass/molar mass

n = m/MM

m = n × MM = 3.60 × 10⁻⁴ mol × (98 g/1 mol) = 0.035 g = 35 mg

(c) Procedure

Dissolve 35 mg of solid H₃PO₄  in enough water to make 80 mL of solution,

2. Moles of solute.

Data:

V = 4900 mL

c = 5.6 mol·L⁻¹

Calculations:

Moles of AlF₃ = cV = 4.9 L AlF₃ × (5.6 mol AlF₃/1L AlF₃) = 27 mol AlF₃

Moles of F⁻ = 27 mol AlF₃ × (3 mol F⁻/1 mol AlF₃) = 82 mol F⁻.

3. Dilution calculation

Data:

V₁= 750 mL; c₁ = 0.80 mol·L⁻¹

V₂ = ?            ; c₂ = 2.0   mol·L⁻¹

Calculation:

V₁c₁ = V₂c₂

V₂ = V₁ × c₁/c₂ = 750 mL × (0.80/2.0) = 300 mL

Procedure:

Measure out 300 mL of stock solution. Then add 500  mL of water.

3 0
4 years ago
A prism refracts white light into rainbow colors because
gogolik [260]

Because each color is refracted differently, each bends at a different angle, resulting in a fanning out and separation of white light into the colors of the spectrum. Water droplets in the air can act in a manner similar to that of a prism, separating the colors of sunlight to produce a spectrum known as a rainbow.

5 0
4 years ago
Calculate the work, w, gained or lost by the system when a gas expands from 15 L to 45 L against a constant external pressure of
marta [7]

Answer:

Work done by the system = 4545 J

Explanation:

The expression for the calculation of work done is shown below as:

w=-P\times \Delta V

Where, P is the pressure

\Delta V is the change in volume

From the question,  

\Delta V = 45 - 15 L = 30 L

P = 1.5 atm

w=-1.5\times 30\ atmL

Also, 1 atmL = 101 J

So,  

w=-1.0\times0.75\times 101\ J=-4545\ J (negative sign implies work is done by the system)

<u>Work done by the system = 4545 J</u>

6 0
3 years ago
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