Question

Question #eb3dd

Answer 1

206.00 `kJ mol^(-1)`

Explanation:

The formula to calculate the heat change of a reaction is
ΔH = -mcΔT (where m is the mass of the fluid whose temperature changes which in this case is water, c is the specific heat capacity of water and ΔT is the change in temperature of water)

Heat change when 0.025 mol of Na is added
= `-100 * 4.18*(35.75-25.00)`
= `-5138.5 J`

Now this is heat change for 0.025 mole of Na.
Enthalpy change means you have to calculate the heat change for 1 mole.

So enthalpy change for 1 mole of Na is `-5138.5/0.025` = 205540 J= 206.00 `kJ mol^(-1)`