An oxygen tank kept at 20 $\circ$ C contains 28.0 moles of oxygen and the gauge reads 31.0 atm.After two weeks,the gauge reads 10.5 atm.How many moles of oxygen were used during the two-week period?
A)9.25 moles
B)7.5 moles
C)20.5 moles
D)18.5 moles
E)9.48 moles

Question

Quizplus · Accepted Answer

We can use the combined gas law to solve for the new number of moles of oxygen in the tank after the two-week period:

(P1V1)/(T1) = (P2V2)/(T2)

Assuming the volume of the tank stays constant, we can rearrange the equation to solve for the new number of moles, n2:

n2 = (P2/T2)(V1/T1) n1

Plugging in the values given:

n2 = (10.5 atm)/(283 K) * (293 K)/(31.0 atm) * 28.0 moles = 18.5 moles

Therefore, the answer is D) 18.5 moles were used during the two-week period.

An Oxygen Tank Kept at 20 ∘\circ∘ C Contains 28

An Oxygen Tank Kept at 20^$\circ$C Contains 28