Chemistry Chapter 5 – Energy changes– endo/exothermic reaction, energy profiles and bond energies Define the terms: Endothermic reaction Exothermic reaction Activation energy Draw and label an energy profile diagram for an exothermic reaction. Complete the sentences below: Breaking bonds is an _____________________ process. Making bonds is an ____________________ process. HIGHER TIER: Write the equation to calculate the bond energy. HIGHER TIER: To decided if a chemical reaction is exothermic or endothermic the amount of energy needed to break/make these bonds must be compared. If a negative sign is in front of the total energy released this means the reaction is exothermic. Calculate the bond energies and state if the reaction is endo or exothermic. H-H 436kJ/mol C=O 799kJ/mol Cl-Cl 242kJ/mol O=H 463kJ/mol C=O 1072kJ/mol H-Cl 436 kJ/mol H2 + Cl2  2HCl H2 + CO2  H2O + CO Give examples for the below reactions: Endothermic reaction Exothermic reaction Draw and label energy profile diagram for an endothermic reaction. Describe the 2 outcomes that can occur when particles collide.

Chemistry Chapter 5 – Energy changes– RP and maths Write a risk assessment for this practical. Include the risk, hazard and control for at least 1 risk. State the equation to calculate the energy transferred by a fuel. (Hint: it is a physics one). State the result you would expect to see for changing the volume of acid. Decimal form begins when 1 is divided by 10 so written as 0.1 or words as one-tenth. Complete the below: One-hundredth is One-thousandth is One-ten thousandth is Describe a method used to investigate the variables that affect temperature change such as metal plus acid plus carbonates, neutralisations and displacements of metals. Explain why heat loss needs to be prevented. Write the variables for the practical endothermic and exothermic reactions. Independent variable – Dependent variable – Control variables – Explain any problems with the solid carbonates that may affect the repeatability of the experiment. State the type of errors that could occur during this practical and give 1 example.