Intro to Thermo + Bond Energy

Front

What is an endothermic reaction?

Back

An endothermic reaction is a chemical reaction that requires energy input, usually in the form of heat, resulting in a temperature drop in the surroundings.

Front

What is an exothermic reaction?

Back

An exothermic reaction is a chemical reaction that releases energy, usually in the form of heat, resulting in a temperature increase in the surroundings.

Front

What does ΔH represent in a chemical reaction?

Back

ΔH represents the change in enthalpy, or heat content, of a system during a chemical reaction.

Front

What happens to bond energy when a chemical bond is broken?

Back

Breaking a chemical bond requires energy, which is absorbed from the surroundings.

Front

What happens to bond energy when a chemical bond is formed?

Back

Forming a chemical bond releases energy, which is given off to the surroundings.

Front

How do you calculate the reaction energy using bond energies?

Back

To calculate reaction energy, sum the bond energies of the reactants and subtract the sum of the bond energies of the products.

Front

What is the bond energy of an O=O bond?

Back

The bond energy of an O=O bond is 494 kJ.

Front

What is the bond energy of an H-O bond?

Back

The bond energy of an H-O bond is 464 kJ.

Front

What is the bond energy of an O-O bond?

Back

The bond energy of an O-O bond is 204 kJ.

Front

In the reaction 2Mg(s) + O2(g) → 2MgO(s), what does ΔH = -1204 kJ indicate?

Back

It indicates that 1204 kJ of energy is released when two moles of magnesium react with oxygen to form magnesium oxide.