module 3 section 2 - physical chemistry

Question 1

Draw a reaction profile for an endothermic reaction

Answer 1

Question 2

Draw a reaction profile for an exothermic reaction

Answer 2

Question 3

Answer 3

Question 4

What is the symbol for standard conditions

Answer 4

Question 5

What is the symbol for enthalpy change under standard conditions

Answer 5

Question 6

What are standard conditions ? (4)

Answer 6

Question 7

What is the symbol for enthalpy change of a reaction ?

Answer 7

Question 8

Show the equation for the enthalpy change of the reaction for magnesium

Answer 8

Question 9

Show the balanced equation for the enthalpy change of the reaction for aluminium including state symbols

Answer 9

Question 10

What is the symbol for standard enthalpy of combustion

Answer 10

Question 11

Show the balanced equation for the standard enthalpy of combustion of the reaction of butane including state symbols

Answer 11

Question 12

What is the symbol for standard enthalpy change of formation

Answer 12

Question 13

Show the balanced equation for the standard enthalpy change of formation of water, include state symbols

Answer 13

Question 14

Show the balanced equation for the standard enthalpy change of formation of carbon dioxide , include state symbols

Answer 14

Question 15

Show the balanced equation for the standard enthalpy change of formation of magnesium sulfate , include state symbols

Answer 15

Question 16

What is the symbol for enthalpy change of neutralisation

Answer 16

Question 17

Show the balanced equation for the enthalpy change of neutralisation for the reaction between hydrochloric acid and sodium hydroxide include state symbols

Answer 17

Question 18

Compare and contrast the enthalpy of products and reactants in an exothermic reaction (2)

Answer 18

• enthalpy of products is lower
• than enthalpy change of reactants

Question 19

Compare and contrast the enthalpy of products and reactants in an endothermic reaction (2)

Answer 19

• enthalpy of products is higher
• than enthalpy change of reactants

Question 20

What is an exothermic reaction (1)

Answer 20

• give out energy
• enthalpy change is negative

Question 21

What is an endothermic reaction (2)

Answer 21

• absorb energy
• enthalpy change is positive

Question 22

What happens to temperature in ectothermic reactions ? (1)

Answer 22

• temp increases

Question 23

What happens to temperature in endothermic reactions (1)

Answer 23

• temp decreases

Question 24

Name 2 exothermic reactions (2)

Answer 24

• combustion of fuel eg methane
• oxidation of glucose in resp

Question 25

Name 2 endothermic reactions (2)

Answer 25

- thermal decomposition of calcium carbonate - PSM

Question 26

What do enthalpy profile diagrams show (2)

Answer 26

- how enthalpy changes - during a reaction

Question 27

What is activation energy (3)

Answer 27

- minimum amount of energy - needed to begin breaking reactant bonds - to start a chemical reaction

Question 28

Describe the stability of a substance in terms of enthalpy (2)

Answer 28

- less enthalpy - = more stable

Question 29

In what ways can you find enthalpy changes ? (2)

Answer 29

- experiment - data books

Question 30

Are products or reactants more stable in an endothermic reaction, explain your answer (2)

Answer 30

- reactants - have less enthalpy

Question 31

Are products or reactants more stable in an exothermic reaction, explain your answer (2)

Answer 31

- products - have less enthalpy

Question 32

Is 🔼H positive or negative in an endothermic reaction ?

Answer 32

Positive

Question 33

Is 🔼H positive or negative in an exothermic reaction ?

Answer 33

Negative

Question 34

Explain why 🔼H is positive in an endothermic reaction (2)

Answer 34

- energy absorbed - to break bonds

Question 35

Explain why 🔼H is negative in an exothermic reaction (2)

Answer 35

- energy released - when bonds are formed

Question 36

What 2 things do u need to know to measure enthalpy change for a reaction ? (2)

Answer 36

- number of moles of substance reaction - change in temp

Question 37

What equation can be used to calculate enthalpy changes

Answer 37

q = mc🔼T

Question 38

What is q in the equation q=mc🔼t

Answer 38

Heat lost or gained

Question 39

What is m in the equation q=mc🔼t

Answer 39

Mass of water

Question 40

What is c in the equation q=mc🔼t

Answer 40

- specific heat capacity of water - 4.18 J g-1 k-1

Question 41

What is 🔼T in the equation q=mc🔼t

Answer 41

- change in temp of water or solution