Acids, Bases, Salt, titration and reactivity series

Question 1

Colour change for Litmus

Answer 1

Acid: Red
Alkali: Blue

Question 2

Colour change for phenolphthalein

Answer 2

Acid: Colourless
Alkali: Pink

Question 3

Colour change for methly Orange

Answer 3

Acid: Red
Alkali: yellow

Question 4

Why is Litmus not suitable for titration indication?

Answer 4

It doesn’t have a clear colour change and no clear end point

Question 5

Colour change for universal indicator

Answer 5

Acid: Red/Brown
Neutral: Green
Alkali: Purple

Question 6

What will form when water is added to acids?

Answer 6

Hydrogen ions (H+)

Question 7

What will form when water is added to alkalis?

Answer 7

Negative hydroxide ions (OH-)

Question 8

What is neutralisation reaction?

Answer 8

When acids and alkalis are mixed together producing salts.

Question 9

Definition of Combination Reaction

Answer 9

When two elements combine to form a compound.

Question 10

Definition of Combustion Reaction

Answer 10

a reaction in which a substance reacts with oxygen gas, releasing energy in the form of light and heat

Question 11

Definition of Displacement Reaction

Answer 11

When a more reactive element displaces a less reactive element from a compound

Question 12

Definition of Decomposition Reaction

Answer 12

When one reactant breaks down into two or more products

Question 13

Difference between alkalis and bases

Answer 13

Bases are insoluble in water and Alkalis are soluble in water

Question 14

Definition of Crystallisation

Answer 14

Process when crystal forms

Question 15

Ionic equation for neutralisation:

Answer 15

H + OH —-> H2O

Question 16

Definition of Precipitate

Answer 16

A solid that is formed by a chemical reaction involving liquids or gases

Question 17

What is a reducing agent?

Answer 17

A substance that tends to lose electron or be oxidized

Question 18

What is a oxidising agent?

Answer 18

A substance that tends to oxidize other substance.

Question 19

What is a Redox reaction?

Answer 19

A reaction that involve the transfer of electrons from one species to another

Question 20

Definition of reductions:

Answer 20

Loss of oxygen and gaining electron

Question 21

Definition of oxidation:

Answer 21

A substance gains oxygen and loses electrons.

Question 22

Acid + Metal —->

Answer 22

Salt + Hydrogen

Question 23

Acid + Alkali —–>

Answer 23

Salt + Water

Question 24

Acid + Base (metal oxide) –>

Answer 24

Salt + Water

Question 25

Acid + Metal carbonate -->

Answer 25

Salt + Water + Carbon Dioxide

Question 26

Acid + Ammonia -->

Answer 26

Ammonium ions

Question 27

How to carry out titration to work out concentration of unknown?

Answer 27

1. Measure 25cm^3 of alkali using a pipette into a conical flask. 2. Add Phenolphthalein 3. Add acid to the burette and note starting volume. 4. Add acid slowly until indicator chages colour. 5. Record final volume and work out difference 6. Repeat to get concordant results.

Question 28

Concordant definition

Answer 28

Results that differ by 0.2 cm^3 or less

Question 29

Steps to make a soluble salt from an acid and an insoluble base

Answer 29

1. Add powdered insoluble reactant to acid in a beaker, one spatula at a time, stirring to mix. Continue adding powder until it is in excess, so that all the acids has reacted. 2. Filter the mixture in the beaker to remove the excess solid. The filtrate now contains only the salt and water. 3. Heat the solution on a evapourating dish over the bunsen burner. Stop heating when small crystals start to form. 4. Leave the solution cool at room temperature. 5. Dry it with filter paper.

Question 30

Equation for rusting

Answer 30

Iron + Oxygen + Water --> hydrated Iron(II) oxide

Question 31

3 Types of rust prevention

Answer 31

Galvanising, Barrier Method, Sacrificial protection

Question 32

How does galvanising protect iron from rusting

Answer 32

Coat iron with a layer of Zinc. Zinc is higher in reactivity series so reacts instead of the iron with oxygen.

Question 33

How does Barrier Method prevent iron from rusting

Answer 33

Coat iron with paint/grease/oil to stop oxygen and water reaching iron

Question 34

How does sacrificial protection prevent iron from rusting

Answer 34

Attach a block of more reactive metal to iron. The more reactive metal is oxidised instead of iron.

Question 35

How does sacrificial protection prevent iron from rusting

Answer 35

Attach a block of more reactive metal to iron. The more reactive metal is oxidised instead of iron.