Acids and alkalis

Question 1

The pH scale shows how __ a substance is. It can be measured using a __ which gives a numerical value.

Answer 1

acidic
ph meter

Question 2

The pH scale ranges from 0 (very __) through 7 (___) to 14 (very__ ).

Answer 2

acidic
neutral
alkaline

Question 3

pH can be also be measured using an indicator and comparing the __ with a comparison chart.

Answer 3

colour

Question 4

Do you think pure water is acidic, alkaline or neutral?

Answer 4

Pure water is neutral.

However, water comes from different sources, like tap water or river water. These water samples have other substances dissolved in them. They might show up as slightly acidic or slightly alkaline because of this.

Question 5

What is used to find the pH of the substances?

Answer 5

A universal indicator.

It gives different colours at different pH values in a rainbow pattern from 0 (red) to 14 (purple). The indicator comes in solution or paper forms.

Question 6

The pH scale is a number scale from __ to __ It tells us how acidic or alkaline an aqueous solution is. The pH scale is used to classify solutions as __, __ or __ .

Answer 6

0
14
acidic
alkaline
neutral

Question 7

Neutral solutions are exactly pH __

Answer 7

7

Question 8

Acidic solutions have pH values less than __ The closer to pH __ , the more acidic a solution is.

Answer 8

7
0

Question 9

Alkaline solutions have pH values more than __. The closer to pH __ , the more alkaline a solution is.

Answer 9

7
14

Question 10

Everyday substances are not__. This makes it difficult to give them a pH value. One type of soap might have a pH of 8, but another have a pH of 9.

Answer 10

pure

Question 11

The term aqueous solutiondescribes a solution that’s made of__ . pH can only be measured in __-based solutions.

Answer 11

water
water

Question 12

Therefore, we can measure a substance’s pH by __ it in water.

Answer 12

dissolving

Question 13

Copper sulfate is a solid in the form of blue crystals. When copper sulfate is dissolved in pure water, we can measure the __ of the solution.

Answer 13

pH

Question 14

The pH of Copper sulfate is approximately 6 which shows that copper sulfate solution is slightly __ .

Answer 14

acidic

Question 15

A substance has a pH of 8. How would it be classified ?

Answer 15

The pH is above 7, so the substance would be classified an alkali.

Question 16

There are 2 methods for testing for pH:

Answer 16

• Using a pH meter
• Using an indicator

Question 17

An indicator is a substance which will change __ depending on the pH of the solution it is mixed with.

Answer 17

colour

Question 18

Some indicators are __ , meaning we can add drops of the indicator to the solution being tested. Other indicators are strips of __ , and we can dip these into the solution.

Answer 18

liquids
paper

Question 19

__ is an example of an indicator. It turns red in solutions that are acidic and it is blue in alkaline solutions.

Answer 19

Litmus

Question 20

Universal indicator is a special indicator because it turns into a different __ at many different pH values.

Answer 20

colour

Question 21

An indicator is added to a solution. It turns green. What is the pH of the solution?

Show answer

Answer 21

It’s not possible to know. There are lots of different indicators and they give different colours at different pH values. Without the exact name of the indicator, it is not possible to know what the colour means.

Question 22

Unlike litmus, __ can show us how strongly acidic or alkaline a solution is, not just that the solution is acidic or alkaline.

Answer 22

universal indicator

Question 23

A few drops of universal indicator are added to water. Then some lemon juice is squeezed in. What colour change would happen?

Answer 23

Lemon juice is acidic (approximately 2 on the pH scale), so the water would change colour from green to yellow/orange.

Question 24

Lots of highly coloured __ and __ can be used to make indicators just by mashing them in hot water.

Answer 24

vegetables
flowers

Question 25

An acid and alkali will\_\_ each other and produce a salt and water.

Answer 25

neutralise

Question 26

What is a neutralisation reaction?

Answer 26

A chemical reaction happens if you mix together an acid and a base.

Question 27

The name of the __ produced can be worked out from the names of the acid and the alkali.

Answer 27

salt

Question 28

What are the names of the substances formed in a neutralisation reaction?

Answer 28

Salt and water.

Question 29

Neutralisation is an __ reaction, so the reaction mixture warms up during the reaction.

Answer 29

exothermic

Question 30

Salts have scientific names. For example, the scientific name of table salt is __ .

Answer 30

sodium chloride

Question 31

Names of salts can be worked out from the names of the __ and the __ that react to make them.

Answer 31

acid alkali

Question 32

There are two parts to a salt name: The first word is a __ , taken from the alkali. The second word ends in ~ide or ~ate, taken from the __ .

Answer 32

metal acid

Question 33

table salt – or sodium chloride - is produced when hydrochloric acid reacts with the alkali sodium hydroxide. The word __ is taken from the alkali, and the word __ from the acid.

Answer 33

sodium chloride

Question 34

There are three acids that are commonly used to make salrs. These are __ , and .

Answer 34

hydrochloric acid nitric acid sulfuric acid

Question 35

A salt made from hydrochloric acid will end in \_\_

Answer 35

chloride

Question 36

A salt made from nitric acid will end in \_\_

Answer 36

nitrate

Question 37

A salt made from sulfuric acid will end in \_\_

Answer 37

sulfate

Question 38

Can you work out the name of the salt made from potassium hydroxide and hydrochloric acid?

Answer 38

Potassium chloride.

Question 39

Working backwards, the names of the acid and alkali reacting can be predicted from the name of the salt. For example, the salt lithium nitrate would have been made from __ and __ .

Answer 39

lithium hydroxide nitric acid

Question 40

The second word in the name of a salt comes from which of the reactants?

Answer 40

The second word of the name is taken from the name of the acid. For example: Hydrochloric acid → chloride Nitric acid → nitrate Sulfuric acid → sulfate

Question 41

Neutralisation reactions can be described using chemical equations like a word equation. This uses the scientific names for the __ and __ placed on the reactant side of the equation. The scientific name for the __ goes on the product side, together with water.

Answer 41

acid alkali salt

Question 42

Acids always have ___ in them.

Answer 42

hydrogen (H)

Question 43

hydrochloric acid has the formula \_\_

Answer 43

HCl

Question 44

sulfuric acid has the formula \_\_

Answer 44

H₂SO₄

Question 45

nitric acid has the formula \_\_

Answer 45

HNO₃.

Question 46

Alkalis have the __ in their formula

Answer 46

hydroxide group OH

Question 47

sodium hydroxide has the formula \_\_

Answer 47

NaOH

Question 48

The H from the acid combines with the OH from the alkali to make the __ . The other elements are used in making the formula of the __ .

Answer 48

water (H₂O) salt

Question 49

Acids react with most __ .

Answer 49

metals

Question 50

When an acid reacts with a metal, the products are a __ and.

Answer 50

salt hydrogen

Question 51

This is the general word equation for the reaction of an acid and a metal:

Answer 51

metal + acid → salt + hydrogen

Question 52

What would the pH of an acidic solution be?

Answer 52

Below 7. A solution with a pH value which is less than 7 is acidic. The acids which react with metals usually have quite a low pH, of either 3 or less.

Question 53

What are the names of the products made in the reaction between an acid and a metal?

Answer 53

Salt and hydrogen.

Question 54

Acids react with some metals to produce a __ and __ gas.

Answer 54

salt hydrogen

Question 55

The abbreviation M.A.S.H. stands for:

Answer 55

Metal + acid → salt + hydrogen

Question 56

When a metal is put in acid, it gets\_\_ and __ as it gets used up in the chemical reaction.

Answer 56

smaller smaller

Question 57

When a metal is put in acid, bubbles of gas can be seen. The bubbles produced in the reaction are __ gas.

Answer 57

hydrogen

Question 58

How can you prove the existence of hydrogen gas?

Answer 58

Using a burning splint because hydrogen is flammable.. When the burning splint is put into the test tube containing hydrogen gas, a small explosion occurs, making a squeaky pop sound.

Question 59

What is seen when a metal reacts with an acid?

Answer 59

- Bubbles being produced - The metal getting smaller

Question 60

If we put the metals in order of their reactivity, from the most reactive down to the least reactive, we get a list called the \_\_

Answer 60

reactivity series.

Question 61

Gold reacts with acids to produce lots of bubbles. True of false?

Answer 61

False! Gold is not a reactive metal, meaning it does not corrode and is easily malleable over a flame, making it a good element for jewellery making.

Question 62

The name of the salt formed from the reaction of a metal and acid can be worked out using the names of the __ and the __ .

Answer 62

metal acid acid

Question 63

The scientific name of table salt is \_\_. It is produced when __ reacts with __ .

Answer 63

sodium chloride sodium hydrochloric acid

Question 64

Naming the salt from the reaction of a metal and an acid 1. The first word is the name of the __ 2. 2. The second word of the name is taken from the name of the

Answer 64

metal acid

Question 65

Magnesium and Nitric acid from \_\_

Answer 65

Magnesium nitrate

Question 66

Calcium and Hydrochloric acid from \_\_

Answer 66

Calcium chloride

Question 67

Zinc and Sulfuric acid from \_\_

Answer 67

Zinc sulfate

Question 68

word equation for magnesium and sulfuric acid

Answer 68

magnesium + sulfuric acid → magnesium sulfate + hydrogen

Question 69

symbol equation for magnesium and sulfuric acid

Answer 69

Mg + H₂SO₄ → MgSO₄ + H₂

Question 70

What is the name of the salt formed when iron reacts with sulfuric acid?

Answer 70

Iron sulfate. The word and symbol equation for this reaction is: Iron + sulfuric acid → iron sulfate + hydrogen Fe + H₂SO₄ → FeSO₄ + H₂

Question 71

what is an acid?

Answer 71

Corrosive substance which has a pH lower than 7. Acidity is caused by a high concentration of hydrogen ions.

Question 72

what is an alkali?

Answer 72

A base which is soluble in water.

Question 73

what is a base?

Answer 73

A substance that reacts with an acid to neutralise it and produce a salt.

Question 74

what does corrosive mean?

Answer 74

Able to damage metal, stonework, clothes and skin. Strong acids and alkalis are corrosive.

Question 75

what does neutralise mean?

Answer 75

To be made neutral by removing any acidic or alkaline nature.

Question 76

Bases are usually: (3)

Answer 76

- metal oxides, such as copper oxide - metal hydroxides, such as sodium hydroxide, or - metal carbonates, such as calcium carbonate

Question 77

Household cleaning products contain strong \_\_

Answer 77

bases

Question 78

Alkalis feel __ when they get on your skin

Answer 78

soapy

Question 79

Just like concentrated acids, concentrated alkalis are ___ . They can attack metals and destroy skin if spilled

Answer 79

corrosive