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.

56.6g

Explanation:

Given that :

Mass of water, m1= 300.0 g

Temperature of water, T1= 22°C

Specific heat capacity of water, C= 4.184 J/g°C

Mass of polystyrene, m2=?

Temperature of polystyrene = 94.9

Specific heat capacity of polystyrene, c2= 1.88 J/g°C

Final temperature = 27.7 oC

Heat lost by polystyrene = Heat gained by water

mc(dT) = mc(dT)

m2 * 1.88 * (94.9 - 27.7) = 300 * 4.184 * (27.7 - 22)

m2 * 1.88*67.2 = 300*4.184*5.7

126.336 * m2 = 7154.64

m2 = 7154.64 / 126.336

m2 = 56.631838

Hence, mass of polystyrene = 56.6g

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