11.6 Discussion: Heat fo Phase Change

Latent heat is

• the heat absorbed or released at a boiling process during a change of phase

• the heat absorbed or released at a constant temperature during a change of phase

• the heat absorbed or released at a constant temperature during a change of phase of 1 kg object

• the heat absorbed or released by an object to increase or decrease its temperature by 1 degree Celcius

The graph shows the cooling curve of a substance. At which stages the specific latent heat released?

• AB and CD

• BC and DE

• AB and EF

• BC and CD

Calculate the energy absorbed by 30 g of 100 ⁰C water that is turned into 100 ⁰C.

• 67 800 J

• 6 7800 J

• 678 J

• 67.8 J

Mathematical Equivalence

ON

How much heat is needed to heat 10g of water from -2^oC to 104^oC in kJ?

ΔH_fus= 6.02 kJ/mol

ΔH_vap= 40.65 kJ/mol

c_water= 4.184 J/g^oC

c_steam= 2.02 J/g^oC

Mathematical Equivalence

ON