Question

Suppose two chemicals are reacted together. It takes 1000 kJ of energy to break the bonds of the reactants and 850 kJ of energy are released by the formation of the products. Which statement is true about the reaction?
A. The reaction is exothermic.
B. The reaction will need an external energy source to proceed.
C. The reaction will give off 150 kJ of energy.
D. The reaction will likely be explosive.

Answer 1

Answer:

B. The reaction will need an external energy source to proceed.

Explanation:

• The energy of the reaction = The energy required to break the bonds of the reactants - the energy released by the formation of the products = 1000 KJ - 850 KJ = 150 KJ.

∴ The reaction is endothermic and needs an external energy source (150 Kj) to proceed.

• Also, the break of reactants bonds requires energy and in this reaction, this reaction requires 1000 KJ.

• The formation of products bonds releases energy and this reaction releases 850 KJ.

• Since, The amount of energy required to break the bonds of the reactants is greater than (by 150 Kj) the amount of energy released by the formation of the products, so The reaction will need an external energy source to proceed.

Answer 2

The true statement is :
B.The reaction will need an external energy source to proceed. It requires 150kJ more for it to take place. The difference between the energy consumed and the energy produced is 150kJ.