5. Chemical Energetics

the following diagram shows the energy profile for the reaction between sodium hydrogen carbonate (NaHCO₃) and Hydrochloric acid.

find the correct relationship between the type of the reaction and statement about energy of reactants and products.

• endothermic - products have more energy than the reactants

• exothermic - products have less energy than the reactants

• exothermic-products have more energy than the reactants

• endothermic - products have less energy than the reactants

what is the WRONG statement regarding the following energy profile?

• Energy is given out during the reaction.

• The products are at a lower energy level than the reactants.

• The reaction is endothermic.

• D The temperature increases during the reaction.

Which reaction is endothermic?

• acid neutralising alkali causing a temperature increase

• adding magnesium to hydrochloric acid

• calcium carbonate decomposing when heated

• combustion of fossil fuels

Which statements about exothermic and endothermic reactions are correct?

1 During an exothermic reaction, heat is given out.

2.The temperature of an endothermic reaction goes up because heat is taken in.

3.Burning methane in the air is an exothermic reaction.

• All

• 1 and 2 only

• 1 and 3 only

• 2 and 3 only

Solutions of two chemicals are mixed. A reaction occurs and the temperature change is measured. Which statement is correct?

• If the reaction is endothermic, the temperature decreases and energy is taken in.

• If the reaction is endothermic, the temperature increases and energy is given out.

• If the reaction is exothermic, the temperature decreases and energy is given out.

• If the reaction is exothermic, the temperature increases and energy is taken in.

A reaction that releases energy to its surroundings is…

• Exothermic
• Endothermic
• Neutral

What happens to the temperature of the surroundings during an endothermic reaction?

• It increases
• It stays the same
• It decreases

What happens to the temperature of the surroundings during an exothermic reaction?

• It increases
• It stays the same
• It decreases

How can you calculate ∆H from bond energy values?

• ∆H=bonds made – bonds broken
• ∆H=bonds made x bonds broken
• ∆H=bonds broken – bonds made

If the reactants have more internal energy than the products, what kind of a reaction must have taken place?

• Exothermic
• Endothermic