[parachute]

Am I doing these problems right?

1. An experiment shows that a 113mL gas sample has a mass of 0.171g at a pressure of 721mmHg and a temperature of 32C. What is the molar mass of the gas?

113mL = 0.113L
32C = 305.15K
721mmHg = 0.949atm

PV = nRT
(0.949)(0.113) = n(8.314)(305.15)
n = 4.2269 x 10E-5mol

M = nm
M = (4.2269 x 10xE-5])(0.171)
M = 7.23g/mol

2. A 145.0g metal sample initially at 95.74C is dropped into 150.0g of water initially at 23.73C. The final temperature of the water and metal is 26.34C. What is the specific heat of the metal? The specific heat capacity of liquid water is 4.184J/g x C.

qmetal = qwater
mΔTC = mΔTC
(145.0)(26.34 - 95.74)C = (150.0)(26.34-23.73)(4.184)
C = -0.16278J/g x C

[UG]

PV = nRT
(0.949)(0.113) = n(8.314)(305.15)
n = 4.2269 x 10E-5mol

If you're using atm and L for your pressure and volume, you need a different R value.

[parachute]

PV = nRT
(0.949)(0.113) = n(8.314)(305.15)
n = 4.2269 x 10E-5mol

If you're using atm and L for your pressure and volume, you need a different R value.

Would it be wiser to just stick to mmHg and mL?

[billnotgatez]

what ever causes you to have the least memorization problems

I like the ATM units so I convert
you may find it easier to remember the various R and avoid the conversion

Of course I avoid having to memorize because I have the conversions and the various R handy, but I am not being tested.