Question

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. How many moles of the gas does the student collect?
0.011 moles.
0.053 moles
0.11 moles
0.53 moles

Answer 1

Answer: First option 0.011 moles

Explanation:

You need to use the formula for Ideal gases which is:

PV = nRT

Where:

P = Pressure (in atm)

V = Volume (In Liters)

n = moles

R = gas constant (this depends of the units; in this case is 0.082 L atm/K)

T = temperature (In K)

From the formula above, we can solve for n:

n = PV / RT

Let's convert first the temperature and volume to K and L respectively:

T = 67 + 273 = 340 K

V = 350 mL / 1000 = 0.35 L

Finally, let's put all the values in the formula above to solve for the value of n:

n = 0.9 * 0.35 / 0.082 * 340

n = 0.315 / 27.88

n = 0.011 moles