CHANGE OF HEAT

Question

How many joules of heat are required to heat 35.0 g of isopropyl alcohol from the prevailing room temperature, 21.2°C, to its boiling point, 82.4°C? (The specific heat of isopropyl alcohol is 2.604 J/g°C.)

Answer 1

Q = m C_P ΔT

 

Q = Heat change (in Joules)

m = mass of substance (in g)

C_P = specific heat at constant pressure (J g^-1 ºC^-1)

ΔT = change in temperature of substance (ºC)

 

m = 35.0 g

C_P = 2.604 J g^-1 ºC^-1

ΔT = T_final - T_initial = 82.4ºC - 21.2ºC

 

Q

= m C_P ΔT

= 35.0 g x (2.604 J g^-1 ºC^-1) x (82.4ºC - 21.2ºC)

= 35.0 g x (2.604 J g-1 ºC-1) x (61.2ºC)

 

Q = 5.58 x 10³ J

(remember sig figs!)