If 392 cm3 of helium at 32°C and 925 torr are cooled to -15°C and the pressure is reduced to 775 torr, calculate the new volume
the gas will occupy.

V₂ = 395.8 cm³

Explanation:

Given data:

Initial volume = 392 cm³

Initial pressure = 925 torr

Initial temperature = 32 °C (32+273 = 305 K)

Final temperature = -15°C (-15+273 = 258 K)

Final volume = ?

Final pressure = 775 torr

Formula:

According to general gas equation:

P₁V₁/T₁ = P₂V₂/T₂  

P₁ = Initial pressure

V₁ = Initial volume

T₁ = Initial temperature

P₂ = Final pressure

V₂ = Final volume

T₂ = Final temperature

Solution:

V₂ = P₁V₁ T₂/ T₁ P₂  

V₂ = 925 torr × 392 cm³ × 258 K / 305 k × 775 torr

V₂ = 93550800 cm³ / 236375

V₂ = 395.8 cm³

the answers would be

the first one and the second one