Chemistry- C7: Energy Changes

What is the law of conservation of energy?

Energy can not be created or destroyed

What is an exothermic reaction?

Energy in the form of heat given out to the surroundings

What is an endothermic reaction?

Energy in the form of heat taken in from the surroundings

Examples of exothermic reactions

\-Combustion

\-Respiration

Examples of endothermic reactions

\-Cooking

\-Photosynthesis

What is activation energy?

The minimum amount of energy required for a reaction start

Where would you label the energy released/taken in on a reaction profile?

The difference between the reactants and the products

What is the key difference between an endothermic/exothermic reaction profile?

Exothermic the reactants have more energy than products, Endothermic the products have more energy than the reactants

Where would you label the activation energy on a reaction profile?

The difference between reactants and peak of the graph

What happens if more energy is required to break the bonds than is released making the new ones?

It is an endothermic reaction

What happens if more energy is released than absorbed?

It is an exothermic reaction

Method for endo/exothermic RP

\-Measure 20cm3 of HCL and Sodium Hydroxide

\-Place thermometers in polystyrene cups and measure starting temperatures of one of the liquids

\-Pour in the other liquid and close lid quicky so no energy gets in or out

\-Start a timer and measure the temperature of the solution every 10s until the reaction is complete

\-Repeat for HCL and Magnesium

\-Compare the difference between the starting/ending temperatures and see what has the greatest difference