a. -395 kJ/mol b. +395 kJ/mol c. -790 kJ/mol d. +790 kJ/mol In a chemical reacti

Question

a. -395 kJ/mol

b. +395 kJ/mol

c. -790 kJ/mol

d. +790 kJ/mol

In a chemical reaction, 65 kJ of energy are needed to break all of the bonds of the reactants, and 85 kJ of energy are required to form the bonds of the products.What is the heat of reaction?

a. +20 kJ

b. -20 k

c. -150 kJ

d. + 150 kJ

In an experiment, 50 ml of HCl were neutralised by 100 ml of NaOH. The heat capacity of the mixture was 400 J/K and the temperature of the mixture rose by 7 K. How much energy was released during this reaction?

a. 2,800 KJ

b. 420,000 kJ

c. 57.1 KJ

d. 140,000 kJ

In an experiment, 500 ml of 0.1 M hydrochloric acid (HCl) is added to 400 ml of sodium hydroxide (NaOH) solution. The acid and base neutralise each other according to the equation: HCl + NaOH ---> NaCl + H2O
How many moles of acid and base were there originally?

a. 0.05 mole of HCl and 0.04 mole of NaOH

b. 0.5 mole of HCl and 0.5 mole of NaOH

c. 0.5 mole of HCl and 0.4 mole of NaOH

d. 0.05 mole of HCl and 0.05 mole of NaOH

Explanation / Answer

1 ) answer : a. -395 kJ/mol

for 2 mol S -790 kJ / mol

for 1 mol -790 / 2 = -395 kJ / mol

2) answer : b. -20 k

DH = breaking energy - making energy

        = 65 -85

        = -20 kJ

3) answer : b. 420,000 kJ

4) answer : d. 0.05 mole of HCl and 0.05 mole of NaOH

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