Question

How much heat is necessary to change 350 g of ice at -20 degrees Celsius to water at 20 Celsius?

Answer 1

Answer:

160790 J

Explanation:

We can find the heat necessary for the ice to go from -20 degrees Celsius to 0 degrees Celsius:

$Q=mc\Delta t$

Where $c=2.09 J/g^{\circ}C$ is the specific heat of ice, that is the amount of heat that must be supplied per unit mass to raise its temperature in a unit.

$Q=(350g)(2.09 J/g^{\circ}C)(0^{\circ}C-(-20^{\circ}C))=14630 J$

We must calculate the latent heat of fusion required for this ice mass to change to water:

$Q=mH$

Where H=334 J/g is the specific latent heat of fusion of water, that is the amount of energy needed per unit mass of a substance at its melting point to change from the solid to the liquid state.

$Q=(350g)(334 J/g)=116900 J$

Then we calculate the heat necessary for the water to go from 0 degrees Celsius to 20 degrees Celsius:

$Q=mc\Delta t$

Where $c=4.18 J/g^{\circ}C$ is the specific heat of water, that is the amount of heat that must be supplied per unit mass to raise its temperature in a unit.

$Q=(350g)(4.18 J/g^{\circ}C)(20^{\circ}C-0^{\circ}C)=29260 J$

Finally the 3 results are added:

$Q_{T}=14630 J + 116900 J + 29260 J=160790 J$