Chemistry

Question 1

What is a combustion reaction?

Answer 1

Fuel+O2–>oxide+energy

-a reaction with oxygen to produce an oxide (burning)

Question 2

What is a neutralisation reaction?

Answer 2

Acid + base = water + salt

Combining of H and OH ions

Question 3

Which compound conducts electricity?

Answer 3

Ionic (called electrolyte)

Question 4

Combustion of a hydrocarbon

Answer 4

CO2+H2O

Question 5

Define physical change

Answer 5

Changes affecting the form (shape) of the chemical substance only but not its chemical composition

Question 6

Define chemical change

Answer 6

Any change that results in the formation of a new substance

Question 7

Evidence of a chemical change

Answer 7

Solid precipitate forms
Heat release
Light produced
Bubbling

Question 8

Evidence of a physical change

Answer 8

Freezing
Melting
Evaporating

Question 9

Physical properties

Answer 9

Texture, colour, melting point, boiling point, density

Question 10

Chemical properties

Answer 10

Toxicity, flammability, radioactivity, acidity

Question 11

How do I identify an acid and a base

Answer 11

Acid formulas start with H and base formals end with OH

Question 12

Test for CO2?

Answer 12

Limewater; will turn cloudy

Question 13

Test for H2?

Answer 13

Burning splint; will pop

Question 14

Test for O2?

Answer 14

Glowing splint: will reignite

Question 15

Name the first 20 elements

Answer 15

Hydrogen
Helium
Lithium
Beryllium
Boron
Carbon
Nitrogen
Oxygen
Fluorine
Neon
Sodium
Magnesium
Aluminium
Silicon
Phosphorus
Sulphur
Chlorine
Argon
Potassium
Calcium

Question 16

What is the correct number of bonds that atoms normally make?

Answer 16

H=1 O=2 C=4

Question 17

Which element is a biological molecule?

Answer 17

Carbon

Question 18

Define isotopes

Answer 18

The same atom with different numbers of neutrons

Question 19

Acids (8)

Answer 19

Sour
Conductive
>7 pH
Releases H+
Litmus paper turns pink
PHTH doesn't change
BPB turns yellow
Reacts with metals

Question 20

Define ionic bond

Answer 20

The complete transfer of valence electrons; generates two oppositely charged ions

Question 21

Define covalent bond

Answer 21

Occurs when ions share electrons

Question 22

Particle theory

Answer 22

1. Matter is composed of tiny particles called atoms
2. Atoms are constantly moving
3. Atoms are faster as temperature increases and vice versa
4. The atom is the smallest building block

Question 23

Characteristics of an incomplete combustion

Answer 23

• lots of soot
• small reaction
• bad smell

Question 24

Characteristics of complete combustion

Answer 24

• hardly any soot
• loud poping noise
• blue flame

Question 25

Bases (8)

Answer 25

Bitter
Conductive
>7
Releases OH-
Litmus turns blue
PHTH turns pink
BPB turns purple
Doesn't react with metals

Question 26

Define pure substance, homogenous, heterogenous

Answer 26

Pure substance: one type of particle; gold
Homogenous: a uniform mixture; air (a mix of gases)
Heterogeneous: a mix of components that aren’t uniform; oil and water