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Physics ice melting SHC and latent heat question

If 5.60 k g of ice were initially at −3.5∘C , how much energy would be taken to warm it to melting point and then melt it?

Reply 1

TSR Jessica

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Reply 2

username3346672

Original post by SamHayes01

If 5.60 k g of ice were initially at −3.5∘C , how much energy would be taken to warm it to melting point and then melt it?

E1 = mc deltaT will calculate the energy required to raise this ice to 0 degrees (it’s melting point). As you’re going from the -3.5 to 0 degrees, delta T will be 3.5 . c is the specific heat capacity of ice which is 4200 J per kg per kelvin. m is the mass of the substance. Putting those numbers in will give you the energy needed to raise the ice to its boiling point.

Then you can calculate the energy required to actually melt the ice by using, E2 = mL where m is once again the mass and L is the latent heat of fusion for ice which is 0.336x10^6 J per kelvin.

Then add the energies together

Reply 3

Alistair912

Original post by SamHayes01

If 5.60 k g of ice were initially at −3.5∘C , how much energy would be taken to warm it to melting point and then melt it?

Assuming this is pure water ice, for every 1 degree Kelvin (or Celsius) increase in temperature, an input of 2.108KJ is required to raise the temperature of 1kg of ice, so we have 5.6KG of ice at -3.5c, therefore, to raise the temperature to 0c, we multiply the mass (5.6KG) by the temperature increase (3.5c) by the Specific Heat Capacity of ice (2.108KJ).=
5.6 X 3.5 X 2108 = 41,316.8J.

Now we have to calculate the enthalpy of fusion (latent heat) as although the ice is at zero degrees, it needs to gain this extra energy to make its phase change (solid to liquid). This extra energy input has no effect on its temperature.

The enthalpy of fusion for water is 334KJ per KG Kelvin, so, we multiply the mass which is 5.6KG by 334000 to get 1,870,400J

We now add the two figures together to get our answer, 41,316.8 + 1,870,400 =
1,911,716.8J

So, the answer to the question of how much heat energy is required to raise 5.6KG of ice to its melting point, it's 1,911,716.8J