C5: Chemical Changes

Question 1

What are the two products formed when a metal reacts with water

Answer 1

Hydroxide and hydrogen

metal + water = metal hydroxide + hydrogen

Question 2

What can we say

Answer 2

The more reactive the metal, the more rapid the reaction

Question 3

What happens when a metal reacts with a dilute acid. Give the equation and the two products formed

Answer 3

Salt and hydrogen

acid + metal = salt + hydrogen

Question 4

What is a displacement reaction

Answer 4

In those reactions, the more reactive metal always takes over the place of a less reactive metal

Eg: copper chloride + magnesium = magnesium chloride + copper

Question 5

What are the two types of reaction

Answer 5

Oxidation and reduction

Question 6

What is oxidation

Answer 6

Oxidation is a loss of electrons and a gain of oxygen

Question 7

What is reduction

Answer 7

Reduction is a gain of electrons and a loss of oxygen

Question 8

What is a redox reaction

Answer 8

Displacement reactions when oxygen is removed from metal oxides

Eg: copper oxide + carbon = copper + carbon oxide

Question 9

What is an ionic equation

Answer 9

When we do a regular balanced equation but involve all the charges of the ions involved in the reaction

Question 10

What is an acid

Answer 10

Acids form acidic solutions in water and produces hydrogen ions in aqueous solutions

Acidic solutions have pH values less than 7

Question 11

What is an alkali

Answer 11

Alkalis form alkaline solutions in water and produces hydroxide ions in aqueous solutions

Alkaline solutions have pH values more than 7

Question 12

What is a neutral solution

Answer 12

They have the exact pH value of 7, and are not alkaline or acidic

Question 13

What is the pH scale

Answer 13

It measures the acidity and alkalinity of a solution.

Question 14

How else can we measure the pH of a solution

Answer 14

Universal indicators

Question 15

What is a base

Answer 15

A base is any substance reacting with an acid to form a salt and water. This shows metal oxides and metal hydroxides are bases

base + acid = salt + water

Question 16

How do we know if a base is alkaline or acidic

Answer 16

If a base is soluble in water, it is alkaline.

If a base is insoluble in water, it is acidic.

Question 17

What is an acid-alkali neutralisation

Answer 17

The reaction between hydrogen and hydroxide ions, forming water

Question 18

When do acids take part in reactions

Answer 18

When salts are produced. Hydrogen ions in acids are then replaced by metal ions

Question 19

What are acids neutralised by

Answer 19

By bases, alkalis and metal carbonates

Question 20

What is the equation for acids and metal oxides. Give the two products and the equation

Answer 20

Salt and water.

Acid + metal oxide = salt + water

Question 21

What is the equation for acids and carbonates. Give the three products and the equation

Answer 21

Carbon dioxide, water and salt

Acid + carbonate = salt + water + carbon dioxide

Question 22

How do we name salts

Answer 22

When naming a salt, it has two parts. The first part comes from the base, alkali or metal carbonate. The second part comes from the acid