C3: Chemical reactions

Question 1

How are the formulae of metal elements written?

Answer 1

In empirical formulae.

Question 2

What are Group 7 elements?

Answer 2

They are diatomic molecules.

Written as: Br2

Question 3

What is conservation of mass?

Answer 3

Mass is never gained or lost in a chemical reaction. (In a closed system)

Question 4

What’s an ionic equation?

Answer 4

Symbol equation but showing ions and their charge.

Question 5

What’s an half equation?

Answer 5

Show the change in charge of an element in a reaction.

Question 6

How can ionic equations be reduced?

Answer 6

Spectator ions are removed. (Same ions on each side)

Question 7

What happens when 2 elements combine? (Name)

Answer 7

The ending is IDE.

E.g. magnesium oxide

Question 8

What happens when 3+ elements combine & one of them is oxygen?

Answer 8

The ending is usually ATE.

E.g. Copper sulphate

Question 9

What’s a mole?

Answer 9

Moles are measurements of chemical amounts.

Question 10

What’s avogadro’s constant.

Answer 10

Number of atoms/molecules/ions in 1 mole of a substance.

6.02 x 10^23

Question 11

What’s equation for moles?

Answer 11

moles = mass/Mr

Question 12

Which metals are less reactive than hydrogen?

Answer 12

Copper, Silver & Gold.

Question 13

What’s an acid?

Answer 13

Contain hydrogen and release hydrogen ions when dissolved ins water.

Question 14

What’re bases?

Answer 14

• Opposite to acids

- Contain elements that react with acids to make water

Question 15

What’s an alkali?

Answer 15

• Are bases

- Contain OH ions

Question 16

Word equations for neutralisation?

Answer 16

Acid + Alkali –> Salt + Water

Question 17

Acid + Carbonate reaction

Answer 17

Acid + Carbonate —> Salt + water + carbon dioxide

Question 18

Metal + Acid reactions?

Answer 18

Acid + Metal —> Salt + Hydrogen

Question 19

What does a catalyst do?

Answer 19

• Lowers activation energy
  So:
• Bonds break more easily
• Reaction is faster

Question 20

What releases energy? EXO

Answer 20

Forming bonds

Question 21

What takes in energy? ENDO

Answer 21

Breaking bonds

Question 22

How to measure pH levels?

Answer 22

• pH Sale
• pH proves
• Universal Indicator

Question 23

What goes to Anode and what goes to Cathode?

Answer 23

Anode (Positive): Negative ions

Cathode (Negative): Positive ions

Question 24

What happens at the anode (electrons)?

Answer 24

Negative ions lose electrons to become atoms/molecules.

Question 25

What happens at the cathode (electrons)?

Answer 25

Positive ions gain electrons to become atoms/molecules.

Question 26

Rules for anode:

Answer 26

If ions are halides, the halogen is produced

If they aren’t halides, oxygen is produced.

Question 27

Rules for cathode:

Answer 27

If ions are more reactive than hydrogen, then hydrogen is produced.
If ions are less reactive than hydrogen, then the metal is produced.