C3

Question 1

Endothermic reaction + examples

Answer 1

More energy transferred to break bonds than is transferred when products form
-photosynthesis

Question 2

What happens to the reaction mixture in an endothermic reaction?

Answer 2

Temp of reaction decreases

Question 3

Exothermic reaction + examples

Answer 3

less energy transferred to break bonds, more transferred when new bonds form

• combustion
• neutralisation

Question 4

Reaction profile for ENDOTHERMIC and energy change

Answer 4

Reactants BELOW products, positive

Question 5

Reaction profile for EXOTHERMIC and energy change

Answer 5

Reactants ABOVE products, negative

Question 6

How to calculate energy change

Answer 6

energy transferred to break bonds - energy transferred when bonds make

Question 7

-, negative energy change

Answer 7

EXOTHERMIC

Question 8

+, positive energy change

Answer 8

ENDOTHERMIC

Question 9

dilute acid

Answer 9

low ratio of acid to volume of solution

Question 10

concentrated acid

Answer 10

high ratio of acid to volume of solution

Question 11

weak acids

Answer 11

partially ionised. only a small fraction of their molecules release H+ ions

Question 12

strong acids

Answer 12

full ionised. all molecules release H+ ions

Question 13

pH + concentration of H+ ions relationship

Answer 13

concentration of H+ decreasing by a FACTOR 10 = increases pH by 1

Question 14

base

Answer 14

usually a metal oxide/hydroxide that can NEUTRALISE ACIDS

Question 15

alkali

Answer 15

bases that can dissolve in water

Question 16

how can mass change in an open system

Answer 16

• gas can leave

- metal can react w o2 in air

Question 17

Mole

Answer 17

unit amount of substance that contains the same no. of entities as there in atoms of 12g of carbon

Question 18

Avogadro’s constant

Answer 18

6.02 x 10^23

Question 19

1 mole of a water MOLECULE = …

Answer 19

3 mol of atoms

Question 20

Acid

Answer 20

substance that releases H+ ions when dissolved in water