Question

A gas has a pressure of 3 atm at 350°C. What will its pressure be at 250°C? The volume and amount of gas is constant. Hint: Convert temperature to Kelvin before calculating (°C + 273 = K)
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Answer 1

We are given:

P1 = 3 atm                  T1 = 623 K (350 + 273)

P2 = x atm                 T2 = 523 K (250 + 273)

Solving for x:

From the idea gas equation:

PV = nRT

since number of moles (n) , Volume (V) and the Universal Gas constant(R) are constants;

P / T = k   (where k is a constant)

the value of  k will be the same for a gas with variable pressure and temperature and constant moles and volume

Hence, we can say that:

P1 / T1 = P2 / T2

3 / 623 = x / 523

x = 523 * 3 / 623

x = 2.5 atm (approx)

Therefore, the final pressure is 2.5 atm