Question

The density of liquid oxygen at its boiling point is 1.14 kg/L , and its heat of vaporization is 213 kJ/kg .

How much energy in joules would be absorbed by 2.0 L of liquid oxygen as it vaporized?

Express your answer to two significant figures and include the appropriate units.

Water's heat of fusion is 80. cal/g , and its specific heat is 1.0calg??C .

Some velomobile seats have been designed to hold ice packs inside their cushions. If you started a ride with ice packs that held 1400 g of frozen water at 0 ?C , and the temperature of the water at the end of the ride was 32 ?C , how many calories of heat energy were absorbed?

Express your answer to two significant figures and include the appropriate units.

Water's heat of fusion is 80. cal/g , its specific heat is 1.0calg??C, and its heat of vaporization is 540 cal/g .

A canister is filled with 390 g of ice and 100. g of liquid water, both at 0 ?C . The canister is placed in an oven until all the H2O has boiled off and the canister is empty. How much energy in calories was absorbed?

Express your answer to two significant figures and include the appropriate units.

Answer 1

1.

mass of oxygen liquid = D*V

                       = 1.14*2 = 2.28 Kg

DHvapourisation = 213 Kj/kg

Amount of heat absorbed = DHvap * m

                        = 213*2.28

                       = 485.64*10^3 joule.

2.

Water's heat of fusion = 80. cal/g

specific heat = 1.0 cal/g⋅∘C .

mass of water = 1400 grams

Heat absorbed (q) = 1400*1*(32-0)+1400*80 = 156800 cal

             = 1.6*10^5 cal

3.
Water heat of fusion = 80. cal/g

specific heat = 1.0 cal/g⋅∘C .

water heat of vaporization = 540 cal/g

Heat absorbed (q) = mice*DHfus + mwater*s*DT + m*DHvap

  
             = 390*80 + (390+100)*1*(100-0)+490*540

             = 3.4*10^5 cal