Question

When one mole of HCl reacts with one mole of NaOH, 1000 calories of heat is produced. How much energy is released when 20 grams of NaOH is reacted?

Answer 1

We know that Molar Mass of NaOH = 40.0 g/mol

Thus, one mol of NaOH has a mass of 40.0 g

Thus, in 20 grams of NaOH, no. of Moles = Mass / Molar Mass = (20 g) / (40.0 g/mol) = 0.50 mol

One mole of NaOH reacts with one mole of HCl to produce 1000 calories.

Thus, heat of reaction will be 1000 cal/mol

Thus, if there are only 0.50 mol of NaOH then only half the energy will be produced.

Thus, energy produced = 1000 cal/mol * 0.50 mol = 500 cal

So, 20 gram of NaOH will produce 500 calories