Question

A sample of neon occupies a volume of 375 ml at stp. What will be the volume of neon If the pressure is reduced to 90.0 KPA?

A. 422 ml
B. 422 L
C. 333 ml
D. 333 L

Answer 1

At STP conditions value of absolute pressure is 101.325 kPa.

From the given data we can determine the new volume of neon using following proportion:

V : V1 = p : p1

375 : V1 = 101.325 : 90

101 * V1 = 90 * 375

V1 =33750/101 =333ml

Answer 2

Since neon is a noble gas we can easily assume its behaviour to be an ideal gas. In ideal gases pressure is said to be inversely proportional to volume,
at fixed temperature, this is Boyle's law.

Therefore we can use this law to state the following equation
P1V1/T1 = P2V2/T2
in this case temperature is fixed therefore it can be eliminated,
then,
P1V1 = P2V2
standard pressure (P1) is 101 325 Pa
V1 = 375 ml
P2 = 90 000 Pa
substituting these values,
101 325 Pa * 375 ml = 90 000 Pa * V2
V2 = 101 325 * 375 / 90 000
= 422.18 ml
After rounding off the final answer is option A - 422 ml