Question

Write chemical equation for the reactions taking place when : (i) manganese dioxide is heated with aluminium powder. (ii)steam is passed over red hot iron. (iii) magnesium reacts with hot water.

Answer 1

Answer:

This will require 266.9kJ of heat energy.

Explanation:

To calculate the energy required to raise the temperature of any given substance, here's what you require:

The mass of the material, m

The temperature change that occurs, ΔT

The specific heat capacity of the material, c (which you can look up). This is the amount of heat required to raise 1 gram of that substance by 1°C.

Here is a source of values of c for different substances:

http://www2.ucdsb.on.ca/tiss/stretton/Database/Specific_Heat_Capacity_Table.html

Once you have all that, this is the equation:

Q=m×c×ΔT

(Q is usually used to symbolize that heat required in a case like this.)

For water, the value of c is 4.186Jg°C

So, Q=750×4.186×85=266858J=266.858kJ