chemical reactions

Question 1

what is a chemical reaction?

Answer 1

two or more chemicals

Question 2

what is a stubstance

Answer 2

a particular kind of matter with uniform properties.

Question 3

what are productas

Answer 3

A substance formed in a chemical reaction.

Question 4

what are reactants

Answer 4

Substances present at the start of a chemical reaction.

Question 5

what are bonds

Answer 5

The chemical link that holds molecules together.

Question 6

what is a word equation

Answer 6

An equation in which only the names of the reactants and products are used to model a reaction

Question 7

what is a balanced equation

Answer 7

An equation in which the symbols and formulae of the reactants and products are used to model a reaction. Also called a symbol equation, balanced symbol equation or chemical equation.

Question 8

how do you write a balanced equasion

Answer 8

replace the name of each substance with its symbol or formula
use numbers to balance the equation, if it is not already balanced

Question 9

what does combustion mean

Answer 9

The process of burning by heat.

Question 10

what does exothermic mean

Answer 10

Reaction in which energy is given out to the surroundings

Question 11

what does endothermic mean

Answer 11

Reaction in which energy is taken in from the surroundings. The surroundings then have less energy than they started with, so the temperature falls

Question 12

what does fuel mean

Answer 12

Material that is used to produce heat, like coal, oil or gas

Question 13

what does hydrocarbon mean

Answer 13

A compound that contains hydrogen and carbon only

Question 14

what is a bace

Answer 14

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

Question 15

what does complete combustion mean

Answer 15

Burning in a plentiful supply of oxygen or air. Complete combustion of a hydrocarbon produces water vapour and carbon dioxide

Question 16

what does incomplete combustion mean

Answer 16

Burning when there is a limited supply of air or oxygen

Question 17

what does oxidation mean

Answer 17

The gain of oxygen, or loss of electrons, by a substance during a chemical reaction

Question 18

what is acid

Answer 18

a substance with particular chemical properties including turning litmus red, neutralizing alkalis, and dissolving some metals; typically, a corrosive or sour-tasting liquid of this kind.

Question 19

what does neutralise mean

Answer 19

To be made neutral by removing any acidic or alkaline nature

Question 20

what does alkaline mean

Answer 20

Having a pH greater than 7

Question 21

what does acidic mean

Answer 21

Having a pH less than 7

Question 22

what does thermal decomposition mean

Answer 22

Type of reaction in which a compound breaks down to form two or more substances when it is heated

Question 23

what does catalyst mean

Answer 23

Changes the rate of a chemical reaction without being changed by the reaction itself

Question 24

what does balanced equation mean

Answer 24

An equation in which the symbols and formulae of the reactants and products are used to model a reaction. Also called a symbol equation, balanced symbol equation or chemical equation.

Question 25

what is limewater

Answer 25

Calcium hydroxide solution. It turns milky in the presence of carbon dioxide.

Question 26

what is the whole meaning of science

Answer 26

is all of the different kinds of things

Question 27

what is an atom

Answer 27

the smallest particle of a chemical element that can exist.

Question 28

what is an other name for combution

Answer 28

Combustion is another name for burning. It is an example of an exothermic

Question 29

what is an element

Answer 29

any material that can not be brockern down

Question 30

what strengths are atoms?

Answer 30

they are hard and strong

Question 31

how many elements are there?

Answer 31

There are over a hundred different types of atom, and these are called elements. Each element has a special name. For example carbon, oxygen and hydrogen are all elements