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Doss [256]
3 years ago
13

A student collects 350 mL of a vapor at a temperature of 67°C. The atmospheric pressure at the time of collection is 0.900 atm.

The student determines that the mass of the vapor collected is 0.79 g. What is the molar mass of the gas?
36 g/mol
72 g/mol
88 g/mol
176 g/mol
Chemistry
1 answer:
Fed [463]3 years ago
6 0

Answer:

Explanation:

This problem is very similar to the other that you put before, so, we'll use the same principle here.

The ideal gas equation: PV = nRT

Where:

P: pressure in atm

V: volume in L

T: Temperature in K.

n: moles

R: Gas constant (In this case, we'll use 0.082 L atm/K)

to get the molar mass of the gas, we need to know the moles, and with the mass, we can know the molar mass. However we can put the ideal gas expression with the molar mass in this way:

we know that n is mole so:

n = g/MM

If we put this in the idea gases expression we have:

PV = gRT/MM

Solving for MM we have:

MM = gRT/PV

Now, let's convert the temperature and volume to K and L respectively:

T = 67 + 273 = 340 K

V = 350 / 1000 = 0.35 L

Now all we have to do is put all the data into the expression:

MM = 0.79 * 0.082 * 340 / 0.9 * 0.35

MM = 22.0252 / 0.315 = 69.92 g/mol rounded 70 g/mol

Now, the closest answer of your options would be 72 g/mol. This could be easily explained because we do not use all the significant figures of all numbers, including the gas constant of R. However, all the work, calculations and procedure is correct and fine, and we only have a minimum range of 2 units.

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4 0
3 years ago
Dalton’s Law CalculationA mixture of H₂, N₂ and Ar gases is present in a steel cylinder. The total pressure within the cylinder
Zolol [24]

Answer:

A) The partial presssure of CO₂ is 167 mm Hg

B) The partial presssure of N₂ is 354 mm Hg

C) The partial presssure of Ar is 235 mm Hg

D) The partial presssure of H₂ is 86 mm Hg

Explanation:

Dalton's law of partial pressures is basically expressed by the following statement:

The total pressure of a mixture is equal to the sum of the partial pressures of its components.

So initially we have:

P_{T}= total presure of the system (675 mm Hg).

P_{N_2}= partial pressure of N₂ (354 mm Hg).

P_{Ar}= partial pressure of Ar (235 mm Hg).

Using Dalton's law we can find the partial pressure of H₂:

P_{T}=P_{N_2}+P_{Ar}+P_{H_2}

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P_{H_2}= 675 mm Hg - 354 mm Hg - 235 mm Hg

P_{H_2}=86 mm Hg

If CO₂ gas is added to the mixture, at constant temperature, and the volume is the same, the difference between the new total pressure and the previous total pressure is equal to the partial pressure of CO₂.

P_{T}=P_{N_2}+P_{Ar}+P_{H_2}+P_{CO_2}

842 mm Hg= 354 mm Hg + 235 mm Hg + 86 mm Hg + P_{CO_2}

P_{CO_2}= 842 mm Hg - 354 mm Hg - 235 mm Hg - 86 mm Hg

P_{CO_2}= 167 mm Hg

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4 0
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