Saturday

April 18, 2015

April 18, 2015

Posted by **Lucy** on Sunday, November 4, 2007 at 3:47pm.

- chemistry -
**DrBob222**, Sunday, November 4, 2007 at 3:51pmPV = nRT

then n = g/molar mass. Post your work if you get stuck.

- chemistry -
**Lucy**, Sunday, November 4, 2007 at 5:13pmSo far I have: (0.385g)(8.31dm3 times kPa)(200K)(1000cm3)/(7.40 kPa)(mol times K)(200 cm3)(1Dm3) which =639870 g/1480 mol which =432.345 and that is not even close to one of the answers. I don't know where I am going wrong.

- chemistry -
**DrBob222**, Sunday, November 4, 2007 at 5:56pmI think your units are messed up.

PV = nRT

It's easier to use atmospheres than kPa. R is 0.08205 L*atm/mol*K when atm is used for pressure, P. V must be in liters. I don't know what grams is doing in PV = nRT

P = 750 torr/760 = ?? atm

V = 200 mL = 0.200 L

n = solve for this

R = 0.08205

T in K = 273 + C = 273-73 = 200 K

So

(750/760)atm x 0.200 L = n x 0.08205 L*atm/mol*K x 200 K.

Solve for n, THEN,

n = # mols = grams/molar mass.

You have mols and grams, solve for molar mass. I hope this helps.

**Answer this Question**

**Related Questions**

chemistry - If 0.385 g of gas occupies a volume of 200 mL at -73 oC and 750 torr...

Chemistry - Help please? 1)A sample of propane gas occupies 625 cm3 at 20.0 °C ...

chemistry - Someone can help me please? A gas sample weighing 0.528 g is ...

Chemistry - A gas occupies a volume of .350 L at a temperature of 18.0 degrees ...

Chemistry 12 - Gases - A gas is initially at 345 K, 821 torr, and occupies a ...

chemistry - A sample of gas with a mass of 1.62 g occupies a volume of 941 mL at...

Chemistry - A quantity of gas weighing 7.10g at 741 torr and 44 degrees C ...

chemistry II - If a 2.15-g sample of gas occupies 750. mL at STP, what is the ...

chemistry II - If a 2.15-g sample of gas occupies 750. mL at STP, what is the ...

Chemistry - I'm having trouble trying to figure out how to setup and solve these...