Question

Suppose that 23 g of each of the following substances is initially at 25.0 ∘C. What is the final temperature of each substance upon absorbing 2.30 kJ of heat? Express your answer using two significant figures. a). gold b). silver c). aluminum d). water

Answer 1

Apply heat equation

Q = m*C*(Tf-Ti)

Ti = 25 for all of them, m = 23 g for all samples

solve for Tf

Tf = Q/(m*C) + Ti

substitute values

Tf = (2.3*10^3)/(23*C) + 25

Tf = 100/C + 25

where C is specific heat of sample

a)

Gold Cp = 0.13 J/gC

substitute

Tf = 100/C + 25 = 100/(0.13) + 25 = 794.2 ºC

b)

Silver Cp = 0.23 J/gC

substitute

Tf = 100/C + 25 = 100/(0.23) + 25 = 459.78 ºC

c)

aluminium Cp = 0.91  J/gC

substitute

Tf = 100/C + 25 = 100/(0.91) + 25 = 134.89  ºC

d)

for water,

Water Cp = 4.184 J/gC

substitute

Tf = 100/C + 25 = 100/(4.184) + 25 = 48.9   ºC