Question

An ideal gas in a sealed container has an initial volume of 2.75 L. At constant pressure it is cooled to 21.00 Celsius where its final volume is 1.75 L. What was the initial temperature?

Answer 1

We know that ideal gas equation is PV = nRT

Where

P = pressure , V = volume , n = number of moles , R = gas constant , T = temperature

As the pressure is kept constant and the gas remains the same , so V is proportional to T

V / V' = T / T'

Where

V =- initial volume = 2.75 L

V ' = final volume = 1.75 L

T = initial temperature = ?

T' = final temperature = 21.00 ^oC = 21.00+273 = 294 K

Plug the values we get ,

T = (T' x V) / V'

   = ( 294 x2.75) / 1.75

   = 462 K

   = 462-273 ^oC

   = 189.00 ^oC

Therefore the initial temperature is 189.00 ^oC