A sample of fluorine gas occupies 855 mL at 710mmHg and 155 degrees Celsius. Wha

Question

A sample of fluorine gas occupies 855 mL at 710mmHg and 155 degrees Celsius.  What is the mass of the sample?

I know to use PV=nRT, n=PV/Rt but how does that equal .02273 mol of gas? Did I miss a conversion somewhere?

Also,

A sample of krypton gas has a volume of 500mL at 225mmHg and -125 degrees Celsius. What's the pressure in mmHg if the gas occupies 220mL at 100 degrees Celsius.  Again, I know to use P1V1/T1=P2V2/T2 but how does it come out to 1288mmHg?

What am I doing wrong?  Help!!! Finals time!

Explanation / Answer

Remember the equation PV=nRT? P is Pressure in atmospheres, V is Volume in L, n is the number of moles, R is a gas constant, and T is the temperature in Kelvin. You have everything except the number of moles, which can be multiplied by the molar mass of F2 gas, 38 grams/mol, to get the mass.

So lets plug it in.

(710 mmHg/760 mmHg per atmosphere)(0.857 L)= n*(.082057 L-atm/mol-K)*(428K).

Simplifying it, you get .8006184211= 35.120396n

Solve for n, and we get .022796395 moles of fluorine gas.

Multiply by molar mass of 38 grams/mol to get the final mass of:

ANSWER: 0.866 grams.  

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.