Paper1-SC8

Question 1

Explain the core practical on prepariing copper sulfate.

Answer 1

Question 2

What is a precipitation reaction?

Answer 2

One in which soluble substances in solutions cause an insoluble precipitate to form.

Question 3

What is oxidation?

Answer 3

Loss of electrons.

Question 4

How can you obtain a dry soluble salt?

Answer 4

From cystalisation, it is important to have a neutral solution before evaporating the water otherwise you will contaminate the salt with an excess of one reactant. This can be done with titration.

Question 5

What happens during neutralisation?

Answer 5

Hydrogen ions in the acid combine with oxide ions to form water.

Question 6

What does metal+acid form?

Answer 6

Salt and hydrogen. Effervescence is seen as hydrogen gas bubbles.

Question 7

Explain the pH scale.

Answer 7

7 neutral, 14 alkaline and 0 acidic.

Question 8

What does carbonate+acid form?

Answer 8

Salt+water+carbon dioxide. Bubbles of carbon dioxide are produced and the solid metal carbonate disapears.

Question 9

What are the main solubility rules?

Answer 9

Question 10

How can we prepare an insoluble salt?

Answer 10

Question 11

Explain how the pH scale goes up.

Answer 11

Concentration of h+ ions goes up by 10 time each time the number goes down by one from 7 and below.

Question 12

What is the equation for concentration?

Answer 12

amount dissolved/volume of solution

Question 13

Why is an excess of thr base added when preparing soluble salts?

Answer 13

To make sure all the acid is used up.

Question 14

What do ionic equations show?

Answer 14

They remove spectator ions and only shows ions that change.

Question 15

How can we predict whether a precipitate will be formed?

Answer 15

We can check the solubility of the products, if both are soluble no precipitate will form.

Question 16

Explain the concentration of hydrogen and hydroxide ions and what they cause.

Answer 16

Question 18

What happens to the ions from acids and alkalis during neutralisation?

Answer 18

Hydrogen ions from the acid reaxt with the hydroxide ions and form water. The other ions stay in the solution as ions of the dissolved salt.

Question 19

Explain some other parts of titration.

Answer 19

Question 20

What is a soluble base?

Answer 20

An alkali.

Question 21

How are the salts produced.

Answer 21

By replacing the hydrogen ions with metal ions.

Question 22

What is the test for carbon dioxide?

Answer 22

Carbon dioxide turns limewater milky. A lighted wooden splint goes out in a test tube of carbon dioxide but this happens with other gases, too. So the limewater test is a better choice.

Question 23

Describe the universal indicator pH scale.

Answer 23

Question 24

Explain the core practical on investigating neutralisation.

Answer 24

Question 25

What are all aqueous solutions?

Answer 25

Neutral, acidic or alkaline.

Question 26

What is reduction?

Answer 26

Gain of electrons.

Question 27

What are the steps of preparing soluble salts?

Answer 27

Question 28

How do we balance chemical equations?

Answer 28

Question 29

When are polyatomic ions formed?

Answer 29

When small groups of atoms held together by covalent bonds lose or gain electrons.

Question 30

How do we make sure the salt is pure?

Answer 30

We filter it.

Question 31

What is the test for hydrogen?

Answer 31

A lighted wooden splint makes a popping sound in a test tube of hydrogen.

Question 32

What is a strong acid?

Answer 32

Low pH values . Their molecules dissociate completely into ions when they dissolve in water and produce high concentration og hydrogen ions.

Question 33

What are the other three main indicators?

Answer 33

Question 34

What are bases?

Answer 34

Bases are substances that neutralise acids to form a salt and water only. Oxide or hydroxide.