Chemistry

Question 1

What is the mass and charge of protons, neutrons and electrons?

Answer 1

Protons - Mass=1 and charge=+1
Neutrons - Mass= 1 and charge=0
Electrons - Mass= 0.0005 and charge=-1

Question 2

Name the first 20 elements of the periodic table and their charges and the names of Fe, Ni, Cu, Zn, Pb, Ag, Sn, Au, Hg.

Answer 2

Hydrogen H
Helium He
Lithium Li
Beryllium Be
Boron	B	
Carbon C	
Nitrogen	 N	
Oxygen O	
Fluorine F	
Neon Ne	
Sodium Na	
Magnesium Mg	
Aluminium Al	
Silicon Si	
Phosphorus P	
Sulfur	S	
Chlorine	Cl
Argon	Ar	
Potassium	K	
Calcium	Ca	

Iron Fe
Nickel Ni
Copper Cu
Zinc Zn
Lead Pb
Silver Ag
Tin Sn
Gold Au
Mercury Hg

Question 3

Complete the general rule for Acid + Metal, Acid + Base, Acid + Carbonate reactions.

Answer 3

Acid + Metal —> Salt + Hydrogen Gas

Acid + Base —> Salt + Water

Acid + Carbonate —

Question 4

What are the mass and charge of protons, neutrons and electrons?

Answer 4

Protons - mass=1 charge=+1

Neutrons - mass=1 charge=0

Electrons - mass=0.0005 charge=-1

Question 5

Describe the atomic structure of an ionic compound.

Answer 5

At least one metal atom bonded with at least one non-metal atom.

Question 6

Describe the atomic structure of a covalent compound.

Answer 6

At least two non-metal atoms bonded together.

Question 7

Explain the role of activation energy in chemical reactions.

Answer 7

The energy that must be supplied for the chemical reaction to occur.

Question 8

What is the law of conservation of mass?

Answer 8

Matter cannot be created or destroyed therefore, the mass of the product(s) will be the same as the mass of the reactant(s).

Question 9

List 3 properties of acids.

Answer 9

• they conduct electricity
• they are corrosive
• they have a sour taste

Question 10

List 3 properties of bases.

Answer 10

• they conduct electricity
• they have a bitter taste
• they create hydroxide ions in a solution

Question 11

What number on the PH scale are strong acids, weak acids, neutral, weak bases and strong bases.

Answer 11

Strong acids- 1
Weak acids- 6
Neutral- 7
Weak bases- 8
Strong bases- 14

Question 12

List 2 examples of strong and weak acids.

Answer 12

Strong

• HCl (hydrochloric)
• H2SO4 (sulphuric)

Weak

• HNO2 (nitrous)
• H3PO4 (phosphoric)

Question 13

List 2 examples of strong and weak bases.

Answer 13

Strong
- LiOH (Lithium Hydroxide)
- NaOH (Sodium Hydroxide)
Weak
- NH3 (ammonia)
- CH3NH2 (methylamine)

Question 14

Explain the concept on concentration in terms of acids and bases.

Answer 14

The concentration of acids and bases is determined by the amount of Hydrogen to Hydroxide ions there are in a solution. The more Hydrogen ions, the more the solution is acidic in concentration. The more Hydroxide ions, the more the solution is basic in concentration.

Question 15

What is an indicator?

Answer 15

A chemical that changes colour to show whether a substance is acidic, neutral or basic.

Question 16

Describe the colour changes of Universal Indicator to signify a strong acid, a weak acid, a strong base, a weak base and a neutral solution.

Answer 16

Red- strong acid
Light green- weak acid
Green- neutral
Faint green- weak base
Purple- Strong Base

Question 17

What colour does litmus turn in acid?

Answer 17

Red

Question 18

What colour does litmus turn in alkali (base dissolved in water)?

Answer 18

Blue

Question 19

Write and word and symbol equation for any acid and base reaction.

Answer 19

Hydrochloric Acid + Sodium Hydroxide —> Sodium Chloride + Water

Question 20

Write a word and symbol equation for any acid and metal reaction.

Answer 20

Hydrochloric Acid + Sodium —> Sodium Chloride + Hydrogen Gas

Question 21

How would you test a gas to see if it was Hydrogen?

Answer 21

The ‘Pop Test’ - Put HCl in a test tube and add a magnesium strip and put another test tube over the original one for a minute. Then take the top test tube away and place a burning match underneath it. If it makes a loud ‘POP’ sound, it is then Hydrogen.

Question 22

Write a word and symbol equation for any acid and carbonate reaction.

Answer 22

Hydrochloric Acid + Potassium Carbonate —> Potassium Chloride + CO2 + Water

Question 23

How would you test a gas to see if it was carbon dioxide?

Answer 23

The ‘Lime Water’ Test- Pass any gas through limewater. If the solution become cloudy, then the gas is Carbon Dioxide.

Question 24

What is the difference between Exothermic reactions and Endothermic reactions?

Answer 24

Exothermic- the temperature of the reaction increases because it requires heat to exit for the reaction to continue.

Endothermic- the temperature of the reaction decreases because it requires heat for the reaction to continue.

Question 25

Define element.

Answer 25

Element- a substance made up of only one type of atom.e.g. Hydrogen (H)

Question 26

Define molecule.

Answer 26

Molecule- a cluster of atoms that makes up an element or compound.e.g. Nitrogen (N2)

Question 27

Define compound.

Answer 27

Compound- a pure substance that is made up of 2 or more different types of atoms chemically joined.e.g. Water (H2O)

Question 28

Define base.

Answer 28

Base- a substance that releases hydroxide ions.

Question 29

Define acid.

Answer 29

Acid- a substance that releases hydrogen ions into an aqueous solution.

Question 30

Define ionic bonding.

Answer 30

Ionic bonding- when cations (positive charged ion) and anions (negative charged ion) are both attracted to one another because of their opposite charges. When they stick together, this is when they’re known as an ionic bond.

Question 31

Define covalent bonding.

Answer 31

Covalent bonding- a chemical bond that involves the sharing of electron pairs between atoms.

Question 32

Write a word equation for a combustion reaction.

Answer 32

Methane + Oxygen Gas —

Question 33

Write a word equation for an incomplete combustion reaction.

Answer 33

Methane + Oxygen Gas —