Chem reactions extra notes

Question 1

Exothermic vs endo differences?

Answer 1

Exothermic-Heat energy is released into the surroundings.
Endothermic-Heat is absorbed by the surroundings

Endothermic-Temperature of the surroundings is decreased
Exothermic-temperature of the surrounding is increased

Endothermic-Enthalpy is positive
Exothermic-Enthalpy is negative

Endothermic-More energy in products than reactants
Exothermic-Less energy in the products compared to the energy in the reactants

Question 2

2 examples of a exothermic reaction?

Answer 2

combustion. respiration, neutralization

Question 3

2 examples of endothermic

Answer 3

Photosynthesis as sunlight is absorbed.
Cooking an egg in a frying pan-Energy being absorbed from the frypan to cook the egg.

Question 4

2 examples of endothermic

Answer 4

photosynthesis, sodium hyrodgen

Question 5

How is energy transferred in chemical reactions?

Answer 5

Through the breaking of chemical bonds in the reactants and creating new bonds in the products.

Question 6

How do you know that a exothermic reaction has taken place

Answer 6

Through an increase in temperature from the reactants to the products.

Question 7

what is meant by the term “thermal decomposition”?

Answer 7

To break down with heat.

Question 8

three strong acids

Answer 8

sulphuric acid. nitric acid, hydrochloric acid.

Question 9

weak acid

Answer 9

carbonic acid

Question 10

strong base

Answer 10

sodium hydroxide

potassium hydroxide

sodium carbonate

Question 11

weak base

Answer 11

ammonia

Question 12

• Concentrated solution:

Answer 12

A concentrated solution is one that has lots of molecules in a volume of water.

Question 13

• Dilute solution:

Answer 13

A dilute solution has very few molecules in a solution of water.

Question 14

whats a weak acid

Answer 14

A weak acid is one that only partially ionises in water.

Question 15

what’s a strong acid

Answer 15

A strong acid is one that almost fully ionises in water.

Question 16

What polyatomic ion is this KNO3 ?

Answer 16

potassium nitrate

Question 17

what polyatomic ion is this CaCO3

Answer 17

Calcium carbonate

Question 18

What polyatomic ion is this Mg(OH)2

Answer 18

Magnesium hyrdroxide

Question 19

what polyatomic ion is this Li3PO4

Answer 19

lithium phospate

Question 20

what polyatomic ion is this NH4Br

Answer 20

Ammonium bromide

Question 21

F. Na2SO4

Answer 21

Sodium sulfate

Question 22

How is respiration similar to combustion -

Answer 22

Glucose combines with oxygen but doesn’t include burning a flame
C6H1206 + O2 -> CO2 + H20
Glucose + Oxygen -> Carbon dioxide + Water

Question 23

Strong base

Answer 23

A molecule that almost fully protonates (accepts all hydrogen ions). Example - Ammonia (NH3)

Question 24

Weak base

Answer 24

A molecule that does not protonate completely (doesn’t accept all hydrogen ions) Example - Sodium Hydroxide (NaOH)

Question 25

What are antacids -

Answer 25

(Milk of Magnesium(Base)) used to relieve pain of too much acid from digestion of food. This is neutralisation.

Question 26

Effects of combustion reactions -

Answer 26

Carbon dioxide produced during combustion reactions can react with water to produce acid rain or acidify oceans.