When heating a substance, energy change = mass of substance $\times$ specific heat capacity $\times$ temperature change.
In school, we may apply this equation over a change in temperature to find the energy put into the system. At the same time, the value for the specific heat capacity is usually a constant.
Is this actually allowed? Surely if the SHC depends on temperature, then using a constant value for the SHC over a temperature change won't give a correct answer?
How does one choose the value for the SHC to use?
For example, if I want to know the energy required to change water from a temperature of $10$ degrees to $50$ degrees, then which value for the SHC of water would I use from this table (in the pictures)?
[Left column shows values for the SHC (right two columns) at the different temperatures in different units.]