Oxygen gas having a volume of 1010 cm3 at 20.7°C and 1.04 x 105 Pa expands until its volume is 1570 cm3 and its pressure is 1.07 x 105 Pa. Find (a) the number of moles of oxygen present and (b) the final temperature of the sample.

final temperature is 469.71 K = 196.71 °C

Explanation:

Given data

volume V = 1010 cm3 = 0.00101 m³

temperature = 20.7°C = 20.7 + 273 = 293.7 K

pressure P1 = 1.04 x 10^5 Pa

volume = 1570 cm3

pressure P2 = 1.07 x 10^5 Pa

to find out

number of moles of oxygen and final temperature

solution

we know that for ideal gas

PV = nRT

put here all value to get n

R gas constant = 8.314472 J/mol-K and T = 293.7 K and V = 0.00101 m³

and P = 1.04 x 10^5

so n = (1.04 x 10^5 * 0.00101) / (8.314472 * 293.7)

n = 0.043015 moles

and

now we use equation

P1V1 / T1 = P2V2 / T2

1.04 x 10^5 * 1010 / 293.7 = 1.07 x 10^5 * 1570 / T2

T2 = 49338663 / 105040 = 469.71 K

so final temperature is 469.71 K = 196.71 °C