Chemical Bonding and Enthalpy Concepts

What is required to break a chemical bond?

• No energy change

• Energy is absorbed

• Energy is required

• Energy is released

What happens to energy when a bond forms?

• Energy is absorbed

• No energy change

• Energy is released

• Energy is required

In the reaction of methane and chlorine, which bonds are broken in the reactants?

• Carbon-carbon and hydrogen-hydrogen

• Carbon-chlorine and hydrogen-chlorine

• Carbon-hydrogen and chlorine-chlorine

• Nitrogen-nitrogen and hydrogen-hydrogen

Which bonds are formed in the products of the methane and chlorine reaction?

• Carbon-carbon and hydrogen-hydrogen

• Carbon-chlorine and hydrogen-chlorine

• Nitrogen-hydrogen and hydrogen-hydrogen

• Carbon-hydrogen and chlorine-chlorine

What is the first step in calculating the change in enthalpy for a reaction?

• Calculate the pressure change

• Determine the reaction rate

• Draw the Lewis structures for reactants and products

• Measure the temperature change

What is the change in enthalpy for the reaction given in the example?

• 80 kilojoules

• -80 kilojoules

• 100 kilojoules

• -100 kilojoules