Question

PLEASE PLEASE PLEASE HELP:
Determining the molar mass of a gas, with M=mRT/PV. m=.947 g, T=102 degrees C, and V= 212.85 mL. P=30.09 inHg. How do I find M? I keep getting a wierd decimal as a mol. How would I find the molar mass? Please help. I'm very stuck.

Answer 1

m=.947 g
T=102 C=375 K
V=212.85 mL=0.21285 L

Answer 2

well what R do u use for that?

Answer 3

.0821?

Answer 4

0.0821 what? unit?

Answer 5

.08206 Latm/molK

Answer 6

right so we need to change P=30.09 inHg.

Answer 7

Into atm? Is it necessary to change units?

Answer 8

yes absolutely...!

because look at ur R units...what do u see?

Answer 9

Oh...atm!

Answer 10

yes so we need to change units

Answer 11

okay

Answer 12

@mukushla

Answer 13

\[30.09 \ \text{inHg}\times \frac{25.4 \ \text{mmHg}}{1\ \text{inHg}} \times \frac{\text{1 atm}}{\text{760 mmHg}}=1.005\ \text{atm}\]

Answer 14

make sense?

Answer 15

Okay, so now how do I calculate M

Answer 16

ok \[M=\frac{mRT}{PV}=\frac{0.947\times0.08206\times375}{1.005\times 0.21285}\]

Answer 17

What do you get as the final answer? (So I can compare...)

Answer 18

136 g/mol

Answer 19

Okay, that's what I got. Thanks for the help!

Answer 20

np :)