Question

A hiker has packed a bag of chips as a snack. At the start of the hike the pressure was 1.5 atm and the temperature was 35*C. At the end of the hike the temperature has dropped to a 0.5*C. What is the pressure at the end of the hike? What would you expect to happen to the bag of chips?

Answer 1

According to Gay-Lussac's Law the temperature and Pressure are directly proportional to each other if the amount and volume of given gas are kept constant.
Mathematically for initial and final states it is expressed as,

                                          P₁ / T₁  =  P₂ / T₂     ----- (1)
Data Given;
                  P₁  =  1.5 atm

                  T₁  =  35 °C + 273  =  308 K

                  P₂  =  ?

                  T₂  =  0 °C + 273  =  273 K

Solving Eq. 1 for P₂,

                                   P₂  =  P₁ T₂ / T₁

Putting values,
                                   P₂  =  (1.5 atm × 273 K) ÷ 308 K

                                   P₂  =  1.32 atm
Result:
           As the temperature is decreased so the pressure also decreases from 1.5 atm to 1.32 atm. Therefore the bag will contract.