Question

A sample of neon (Ne) occupies 1700 mL at STP. At constant pressure, what temperature is necessary to increase the volume to 2100 mL?

A sample of neon (Ne) occupies 1700 mL at
STP. At constant pressure, what temperature
is necessary to increase the volume to 2100
mL?
1. 32◦C
2. 52◦C
3. −52◦C
4. −14◦C
5. 64◦C

Answer 1

5, 64 degrees C

Explanation:

The ideal gas law states that PV=nRT, we want to keep pressure constant and solve for an increase in temp that corresponds to an increase in volume. So we can set up a relationship between the first and last states. Solving for n (we know that number of moles will remain constant) we get the following:

`n_1 = (P_1*V_1)/(R*T_1)` and the same for the second state. Since they are equal we can set them equal to each other, so:

`(P_1*V_1)/(R*T_1)=(P_2*V_2)/(R*T_2)` We now simplify.
`(color(red)(cancel(P_1))*V_1)/(color(red)(cancel(R))*T_1)=(color(red)(cancel(P_2))*V_2)/(color(red)(cancel(R))*T_2)`
So:
`V_1/T_1 = V_2/T_2`
`T_2 = (V_2*T_1)/V_1`
`T_2 = 2100*273/1700`
`T_2 = 337.2 "K" = 64.2 "C"`

So the answer is 5, 64 degrees C.

Hope this helps!