a sample of hydrogen gas has a volume of 145 mL when measured at 44*C and 1.47 atm. what volume?

Question

please explain to me how to do this problem, i dont get it :(

a sample of hydrogen gas has a volume of 145 mL when measured at 44*C and 1.47 atm. what volume would the hyrogen sample occupy at STP?

Answer 1

You would solve this problem with this general equation:
[(P1)(V1)] / T1 = [(P2)(V2)] / T2

In this case, you're trying to find the second volume, so solve for V2:
V2 = [(P1)(V1)(T2)] / [(T1)(P2)]

STP = standard temperature and pressure
standard temperate = 273.15 K
standard pressure = 1.00 atm

Given information:
P1 = 1.47 atm
V1 = 145 mL
T1 = 44*C + 273.15 = 317 K (yeah, you have to turn all the temperatures in Kelvin when dealing with the gas law, or else it won't come out right)
P2 = 1.00 atm
T2 = 273.15 K

The answer should have three significant figures. Can you see why? ^_^

Now, just plug in all your givens into the right spot and solve for V2:

V2 = [(1.47 atm)(145 mL)(273.15 K)] / [(317 K)(1.00 atm)]
V2 = 184 mL

Yay! You found the volume! Congratz!

Answer 2

Your gas is measured at a pressure other than standard pressure (1.0 atmosphere), so you have to correct the volume for this.

Your gas is also measured at a temperature other than standard temperature (273 K) so you have to correct the volume for this.

If you combine Boyle's Law (needed for the pressure correction) and Charles' Law (needed for the temperature correction) you would use the formula:

P1V1/T1 = P2V2/T2

P1, V1, T1 are your original numbers (don't forget to change celcius to kelvin by adding 273).

P2 is your standard pressure, 1.0 atm
T2 is your standard temperature, 273 K
V2 is your unknown.

Plug in the numbers and chug out an answer.

Answer 3

PV = nRT

Where pressure is in Atm
Volume is in Liters
n is in moles of gas
R is a constant (.08206)
T is in kelvin

This is the eqation you should remember whenever doing gas problems. However this isn't the equation we need to use right now, but rather a derivitive of it:

[(P1)(V1)]/(T1) = [(P2)(V2)]/(T2)

this equation is used to compair a gas that has changed in some way, you should be framiliar with this equation if you are asking this question....

simply plug in your numbers....
add the numbers for ideal gasses...
(1 mole of a gas at STP occupies 22.4 Liters at 1atm and 273.15K)
we are looking for volume so that is our unknown

[(1.47)(.145)]/(44+273.15) = [(1)(V2)]/(273.15)

simple algebra after that...

answer == 0.18 Liters
or 180mL if you prefer.

Answer 4

This question was asked before ... using the combined gas law find P2 [P1 x V1] / T1 = [P2 x V2] / T2 [ 2.20 x 859 mL ] / 565 K = [P2 x 268 mL] / 815 K 3.34 = [P2 x 268 mL] / 815 K 2722.1 = P2 x 268 mL P2 = 10.16 atm

Answer 5

The formula is PV=nRT
P=pressure (atm)
V=volume (L)
n=amount of moles (mol)
R=constant [0.082058 L*atm/(K*mol)]
T=temperature (K)
and you can calculate the volume on your own now by using a little bit of solving an Algebra problem.