Chemistry Ka4

Question 1

How does a sodium atom change into a sodium ion?

Answer 1

By losing two electrons

Question 2

Under what conditions will an ionic compound conduct electricity?

Answer 2

Molten or dissolved in water (aqueous)

Question 3

What is an electrolyte?

Answer 3

The liquid or solution which is able to conduct electricity

Question 4

What is the positive electrode called?

Answer 4

Anode

Question 5

What is the negative electrode called?

Answer 5

Cathode

Question 6

What is the equation for the positive electrode when the molten compound used is copper chloride (chlorine Cl₂)

Answer 6

2Cl⁻ - 2e⁻ –> Cl₂

Question 7

What is the equation for the product at the negative electrode when the molten compound used is copper chloride (copper Cu)?

Answer 7

Cu² ⁺ + 2e⁻ –> Cu

Question 8

When passing electricity through a molten salt what ions move to the negative electrode?

Answer 8

The positive ions

Question 9

What two substances are formed when molten sodium chloride is broken down by electricity?

Answer 9

Sodium and chlorine

Question 10

How is sodium chloride found?

Answer 10

In rock salt and dissolved in oceans

Question 11

What is the formula for sodium chloride?

Answer 11

NaCl

Question 12

What can all charged particles do?

Answer 12

Freely move

Question 13

What is chlorine used for?

Answer 13

Disinfectant in pools

Question 14

What is hydrogen used for?

Answer 14

Rocket fuel

Question 15

What is sodium hydroxide used for?

Answer 15

In bleach

Question 16

Name the ions in sodium chloride solution

Answer 16

Sodium ions

Chlorine ions

Question 17

Explain sodium chloride (molten)

Answer 17

Contains only sodium ions and chloride ions.

The products are sodium and chlorine

Question 18

Explain sodium chloride (solution/dissolved in water)

Answer 18

Contains only sodium ions, chloride ions, hydrogen ions m, hydroxide ions. The products are chlorine, hydrogen and sodium hydroxide

Question 19

Explain what happens during electrolysis of hair

Answer 19

The positive electrode is connected by a patch of skin. The negative electrode is connected to the hair. The body fluid is a solution containing sodium chloride. The electricity causes the electrolysis of a small amount of this solution. Hydrogen ions move to the negative electrode because they have a positive charge. Chlorine gas is produced. A strong alkali called hydroxide is formed around the hair follicle. This helps to break down the follicle

Question 20

What is electrolysis?

Answer 20

The decomposition of a substance to give simpler substances.

Question 21

What must the substance being electrolysed be?

Answer 21

An ionic compound

Question 22

What is the substance being decomposed during electrolysis called?

Answer 22

The electrolyte

Question 23

What happens to the electric current during electrolysis?

Answer 23

It enters and leaves the electrolyte by conducting rods called the electrodes

Question 24

What must be for electrolysis to occur?

Answer 24

The electrolyte must be in liquid form so that the ions are free to move. The negative ions move towards the anode. When they get there they lose electrons to form neutral atoms. The positive ions move towards the cathode, there they gain electrons to form a neutral charge atoms

Question 25

When the solid used is sodium chloride: State the liquid used, name of solution made, ions present in the solution, ions at positive electrode, ions at negative electrode :

Answer 25

Water, sodium chloride, sodium : chloride : hydrogen : hydroxide ions , chloride (Cl⁻) : hydroxide (OH⁻), sodium (Na ⁺) hydrogen (H ⁺)

Question 26

How do you work out the products at the negative electrode?

Answer 26

Hydrogen is produced if the metal is more reactive than hydrogen. If not, the metal is produced

Question 27

How do you find the products at the positive electrode?

Answer 27

Oxygen is produced unless the solution contains halide ions (chloride, bromide etc) when the halogen is produced