Question

The accepted value for the enthalpy for the following reaction reaction is 466.85 kJ/mol.

Mg + 2Hcl = MgCl2 + H2

Calculate the heat that would be generated if 5.00g of magnesium reacts with excess hydrochloric acid.

I don't even know how to start this problem, please help

Answer 1

Reason it out. Use the equation. That tells you that 1 mol Mg (that's 24.3 grams Mg) evolves 466.85 kJ. So what will 5.00 g Mg evolve? You can set up a ratio/proportion or use
466.85 kJ x (5.00 g/24.3g) = ? kJ.

The ratio/proportion looks like this.
(5.00/24.3) = (x kJ/466.85 kJ)