Question #afa15

1 Answer
Dec 16, 2015

"31 mL"31 mL

Explanation:

Your tool of choice for any ideal gas problem will always be the ideal gas law equation. You can derive any other gas equation by using the ideal gas law equation, so always start with that in mind.

So, your sample of nitrogen gas, "N"_2N2, goes from a volume of "30.0 mL"30.0 mL, a temperature of 25^@"C"25C, and a pressure of "730 mmHg"730 mmHg, to a temperature of 50^@"C"50C and a pressure of "1 atm"1 atm.

This tells you that you can use the ideal gas law equation to describe the two states of the gas

P_1 * V_1 = n * R * T_1 ->P1V1=nRT1 for the initial state

P_2 * V_2 = n * R * T_2 ->P2V2=nRT2 for the final state

Notice that you can divide these equations to get

(P_1 * V_1)/(P_2 * V_2) = (color(red)(cancel(color(black)(n * R))) * T_1)/(color(red)(cancel(color(black)(n * R))) * T_2)

This is equivalent to

(P_1V_1)/T_1 = (P_2V_2)/T_2 -> the combined gas law equation

Now all you have to do is plug in your values and solve for V_2. Do not forget to convert the pressure from mmHg to atm and the temperature from degrees Celsius to Kelvin!

"1 atm " = " 760 mmHg"

This will get you

V_2 = P_1/P_2 * T_2/T_1 * V_1

V_2 = (730/760color(red)(cancel(color(black)("atm"))))/(1color(red)(cancel(color(black)("atm")))) * ( (273.15 + 50)color(red)(cancel(color(black)("K"))))/( (273.15 + 25)color(red)(cancel(color(black)("K")))) * "30.0 mL" = "31.23 mL"

You should round this off to one sig fig, but I'll leave it rounded to two sig figs

V_2 = color(green)("31 mL")