9.1 Ethalpy Changes

Question 1

How to you draw a reaction profile?

Answer 1

Label:
Reactants
Products
Activation energy
Enthalpy change

Question 2

What is the symbol for enthalpy change?

Answer 2

Delta H

Question 3

What is enthalpy change?

Answer 3

Change in temp

Question 4

Does the temp go up or down in endothermic reactions?

Answer 4

Down as energy is taken from the surroundings and the solution

Question 5

What is activation energy?

Answer 5

Minimum energy required to start a reaction

Question 6

What is the saying to remember bonds breaking and making?

Answer 6

Mexo and Bendo

Question 7

What is the definition for standard enthalpy change?

Answer 7

At standard pressure 100kPa
Standard temp of 298K
Conc of 1mol/dm3
In aqueous solution

Question 8

What is the symbol for standard enthalpy change?

Answer 8

Delta H to the power of a flying saucer

Question 9

What is the standard state?

Answer 9

100 kPa
298K
1 mol/dm3

Question 10

What is the symbol for standard enthalpy of reaction and what is it?

Answer 10

Delta small r H to the flying saucer
Enthalpy change that accompanies a reaction in the molar quantities under standard conditions with reactants in standard state

Question 11

What is the symbol for standard enthalpy of formation and what is it?

Answer 11

Delta f H to the flying saucer
When 1 mol is formed with its elements under standard conditions with reactants and products in standard state

Question 12

What is the symbol for standard enthalpy of combustion and what is it?

Answer 12

Delta c H to the flying saucer
1 mol of substance reacts completly with O2 under standard conditions + states

Question 13

What is bond enthalpy?

Answer 13

Energy to break 1 mol of a bond in gas form

Question 14

What does + or - enthalpy change mean?

Answer 14

• delta H = exothermic
  + delta H = endothermic