Endothermic and Exothermic Reactions

The video tutorial explains chemical reactions, focusing on combustion as an exothermic reaction that releases energy. It introduces the concept of enthalpy and how to identify exothermic reactions. The tutorial also covers endothermic reactions, which absorb energy, and discusses the processes of bond breaking and making, highlighting their roles in energy changes during reactions.

What is the primary characteristic of an exothermic reaction?

• It releases energy.

• It absorbs energy.

• It requires a catalyst.

• It feels cold.

In a chemical equation, what do the numbers in front of the chemical formulas represent?

• The state of the substance.

• The temperature of the reaction.

• The speed of the reaction.

• The mole ratio of the substances.

How is the change in enthalpy (ΔH) calculated for a reaction?

• By adding the enthalpy of reactants and products.

• By subtracting the enthalpy of reactants from the enthalpy of products.

• By subtracting the enthalpy of products from the enthalpy of reactants.

• By multiplying the enthalpy of reactants and products.

What is the sign of the change in enthalpy (ΔH) for an exothermic reaction?

• Undefined

• Zero

• Negative

• Positive

What is a key feature of endothermic reactions?

• They release energy.

• They feel hot.

• They absorb energy.

• They occur spontaneously.

Why does melting ice represent an endothermic reaction?

• Because it absorbs heat.

• Because it releases heat.

• Because it forms new bonds.

• Because it occurs at high temperatures.

How can you recognize an endothermic reaction by touch?

• It feels hot.

• It feels sticky.

• It feels neutral.

• It feels cold.

What happens to energy during bond breaking?

• Energy is converted to mass.

• Energy remains constant.

• Energy is absorbed.

• Energy is released.

Which of the following is true about bond making?

• It releases energy.

• It requires energy input.

• It is an endothermic process.

• It decreases the temperature.

What is the relationship between bond making and energy?

• Bond making is temperature-dependent.

• Bond making requires a catalyst.

• Bond making releases energy.

• Bond making absorbs energy.