DF1 + DF2

Question 1

exothermic reactions

Answer 1

enthalpy change is -ve
reactants have more energy than products
more energy is released in making bonds than is used in breaking bonds
energy transferred to surroundings

Question 2

endothermic reactions

Answer 2

enthalpy change is +ve
products have more energy than reactants
more energy required to break bonds than is released from breaking bonds
energy taken in from surroundings

Question 3

standard conditions

Answer 3

298K (25 celcius)
1moldm-3 solutions
1atm pressure

Question 4

standard enthalpy change of combustion

Answer 4

enthalpy change when one mole of a substance is burnt completely in oxygen under standard conditions

Question 5

standard enthalpy change of reaction

Answer 5

enthalpy change when molar quantities of reactants react together unde rstandard conditions

Question 6

standard enthalpy change of formation

Answer 6

enthalpy change when one mole of a substance is formed from its elements under standard conditions

Question 7

standard enthalpy change of neutalisation

Answer 7

enthalpy change when one mole H+ reacts with one mole of OH- and one mole of water is formed

Question 8

Hess’ law

Answer 8

the enthalpy change of a reaction is idependent of the intermediate stages provide the initial and final conditions are the same for each route