Question

An ideal gas is heated under constant pressure (P_ext = 2 bar) from an initial volume of 1 liter and temperature 25⁰C to a final temperature of 37⁰C. what is the final volume of the gas? how many moles of gas are involved?

Answer 1

Please note the temperatures (temperature 25⁰C to a final temperature of 37⁰C considered) mentioned.

=====An ideal gas is heated under constant pressure (P_ext = 2 bar) from an initial volume of 1 liter and temperature 25⁰C to a final temperature of 37⁰C. what is the final volume of the gas? how many moles of gas are involved?====

At constant pressure, from the gas laws we know,

P1V1/T1 = P1V2/T2,

or V1T2 = V2T1

Where 1 stands for initial and 2 for final,

V1 = 1 L

T1 = 25⁰C = 298 K and T2 = 37⁰C = 310 K

V2 =?

From the above formula, V2= 1*310/298 L = 1.0403 L is the final volume.

Again, from the gas laws, we can write,

PV=nRT

By replacing the initial state values and considering R= 0.082 L atm / mol K

we get, n = 1.97385*1/0.082/298 ( 2 bar = 1.97385 atm) = 0.0808 moles of gas was present.