GCSE Chemistry - Bond Energies #44 (Higher tier)

The video tutorial explains bond energies and their significance in determining whether a chemical reaction is exothermic or endothermic. It describes bond energy as the energy required to break one mole of a covalent bond and highlights that breaking bonds is endothermic while forming bonds is exothermic. The tutorial provides examples of reactions, such as hydrogen with chlorine and nitrogen with hydrogen, to demonstrate how to calculate the overall energy change by comparing the energy required to break bonds with the energy released during bond formation.

What does bond energy refer to in the context of chemical reactions?

• The energy released when a bond is formed

• The energy required to break one mole of a specific covalent bond

• The energy needed to form one mole of ionic bonds

• The total energy of a chemical reaction

Which of the following processes is endothermic?

• Breaking of hydrogen bonds

• Formation of hydrogen chloride bonds

• Formation of chlorine bonds

• Breaking of ionic bonds

How do you determine if a reaction is exothermic or endothermic?

• By counting the number of molecules involved

• By measuring the temperature change of the reaction

• By calculating the difference between energy required to break bonds and energy released by forming bonds

• By comparing the number of bonds broken and formed

In the reaction between hydrogen and chlorine, what is the overall energy change?

• -16 kilojoules per mole

• -184 kilojoules per mole

• +184 kilojoules per mole

• 0 kilojoules per mole

What is the overall energy change for the reaction between nitrogen and hydrogen?

• +184 kilojoules per mole

• +16 kilojoules per mole

• -16 kilojoules per mole

• -184 kilojoules per mole