Question

A sample of polystyrene, which has a specific heat capacity of 1.880 J.g .°C , is put into a calorimeter (see sketch at right) that contains 300.0 g of water. The polystyrene sample starts off at 94.9 °C and the temperature of the water starts off at 22.0 When the temperature of the water stops changing it's 27.7 °C. The pressure remains constant at 1 atm. Calculate the mass of the polystyrene sample. Be sure your answer is rounded to 2 significant digits.

Answer 1

m(water) = 300.0 g

T(water) = 22.0 oC

C(water) = 4.184 J/goC

m(polystyrene) = to be calculated

C(polystyrene) = 1.88 J/goC

T = 27.7 oC

We will be using heat conservation equation

use:

heat lost by polystyrene = heat gained by water

m(polystyrene)*C(polystyrene)*(T(polystyrene)-T) = m(water)*C(water)*(T-T(water))

m(polystyrene)*1.88*(94.9-27.7) = 300.0*4.184*(27.7-22.0)

m(polystyrene)*126.336 = 7154.64

m(polystyrene)= 56.6 g

Answer: 57 g