How many grams of methane gas (CH4) are in a 15.8 liter sample at 1.2 atmospheres and 27°C? Show all work used to solve this problem.

Question

aaronq · Answer

first find the moles (n) of gas present, use PV=nRT

you need to convert the temperature from Celsius to Kelvin.

anonymous · Answer

Is that when you add 274 to 27?

aaronq · Answer

yeah 273 + 27 

R in these units is 0.08206

aaronq · Answer

After you've found the moles you wanna convert them to grams

$\sf moles=\dfrac{mass}{molar ~mass}$

anonymous · Answer

how do you finds the moles?

somy · Answer

PV= nRT 
P= pressure
V= volume 
n= mole 
R= constant = 0.08206 
T= temperature

somy · Answer

put the values into the formula and get the mole

anonymous · Answer

what would p be?

anonymous · Answer

I am so confused I have literally been staring at this problem and another one for and hour trying to figure it out.

aaronq · Answer

P is pressure, it varies in units, in this problem it's given as atmospheres (ATM)

anonymous · Answer

oh okay. so it would be set up like 
1.2 atm x 15.8 liter = n0.08206 x 300

anonymous · Answer

would the answer be 0.77?

somy · Answer

yes

anonymous · Answer

Thank you!

somy · Answer

oh u r not finished tho lol :)

anonymous · Answer

Oh aha then what do I do now?

anonymous · Answer

would i use stoich and convert the mols to grams?

anonymous · Answer

would the final answer be 0.048

somy · Answer

nope

somy · Answer

look 
mole= mass/ Molecular mass
so mass= mole* Molecular mass
 you got mole = 0.77
molecular mass of CH4= 12+4= 16 
thus mass= 0.77* 16=

somy · Answer

the answer will be your mass