Energetics 0.0 / 5 ? ChemistryEnergeticsASEdexcel Created by: Nim9Created on: 09-04-17 17:31 Define enthalpy change. Amount of heat energy taken in or given out during any change in a system provided the pressure is constant. kJ/mol 1 of 12 Define exothermic and list three exothermic reactions. Energy is transferred from system to surroundings. Combustion, neutralisation, respiration 2 of 12 Define endothermic and list three endothermic reactions. Energy is transferred from surroundings to system. Thermal decomposition, photosynthesis, dissolving of potassium nitrate. 3 of 12 Define standard enthalpy change of reaction. The enthalpy change measured when the number of moles of substances in the equation as written react, under standard conditions 298K and 1 atm. 4 of 12 What is Hess's Law? The total enthalpy change involved in converting reactants into products is the same regardless of the route taken. 5 of 12 What is the standard enthalpy change of formation? The enthalpy change when one mole of compound is formed from its elements in their standard states under standard conditions, 298K and 1 atm. 6 of 12 What is the enthalpy change of formation for an element? 0 kJ/mol 7 of 12 Name the assumptions during experiments to calculate enthalpy changes. No heat is transferred between the solution and surroundings. Solution has same density and specific heat capacity as water. 8 of 12 Define the standard enthalpy of combustion. Enthalpy change that occurs when one mole of the substance undergoes complete combustion under standard conditions, 298K and 1 atm. 9 of 12 Define the standard enthalpy change of neutralisation. enthalpy change measured when one mole of H ions neutralises a mole of OH ions to form a mole of water. 10 of 12 What is a bond enthalpy? enthalpy change when a mole of bond in the gaseous state is broken. 11 of 12 Define mean bond enthalpy. Enthalpy needed to break the covalent bond into gaseous atoms, submerged over different molecules. 12 of 12
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