CHEMISTRY - Chemical Changes, Electrolysis

Question 1

What does OIL RIG stand for in terms of electrons?

Answer 1

Oxidation is loss.
Reduction is gain.

Question 2

Have a look at the laminated sheet on how to prepare a dry sample of a soluble salt from an insoluble oxide or carbonate.

Answer 2

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Question 3

What is meant by a displacement reaction?

Answer 3

Where a more reactive metal will displace a less reactive metal from a compound.

Question 4

What are some common ions and their charges?

Answer 4

Nitrate ion - N03,-
Sulphate ion - S04,2-
Hydroxide ion - OH,-
Ammonium ion - NH4,-
Carbonate ion - CO3,2-

Question 5

Acid + Alkali = ?

Answer 5

Salt + Water

Question 6

Metal + Acid = ?

Answer 6

Salt + hydrogen

Question 7

Metal oxide + Acid = ?
Metal Hydroxide + Acid = ?

Answer 7

Salt + Water

Question 8

Metal carbonate + Acid = ?

Answer 8

Salt + CO2 + Water

Question 9

When dissolved in water, what do acids produce?

Answer 9

Hydrogen ions.

Question 10

When dissolved in water, what do alkalis produce?

Answer 10

Hydroxide ions.

Question 11

What charge do elements in group 1,2,3,6,7 have?

Answer 11

Group 1 = +1
Group 2 = +2
Group 3 = +3
Group 6 = -2
Group 7 = -1

Question 12

What is the relationship between the hydrogen ion concentration and the strength of an acid?

Answer 12

Strong acids have a higher hydrogen concentration than weak acids because they completely ionise unlike weak acids which don’t.

Question 13

What is the order of reactivity series?

Answer 13

Potassium
Sodium
Calcium
Magnesium
Aluminum
Carbon
Zinc
Iron
Lead
Hydrogen
Copper
Silver
Gold
Platinum

Question 14

Why does electrolysis only work with aqueous or molten ionic compounds?

Answer 14

The ions need to be free to move and are not able to do this in solids, liquids or gases.

Question 15

Have a look at the laminated sheet and learn how to write ionic equations from symbol equations.

Answer 15

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Question 16

What happens when metals react with other substances?

Answer 16

Metal atoms lose electrons to form positive ions.

Question 17

What are some signs to show whether a metal is more reactive or not?

Answer 17

• The more vigorous its reactions are
• The more easily it loses electrons in reactions to form positive ions (cations)

Question 18

Describe and explain the observations when a small piece of lithium is placed on the surface of a big container of water. A few drops of universal indicator have been added to the water.

Answer 18

There is fizzing as the lithium reacts with the water to produce hydrogen gas. The colour of the universal indicator changes from green to purple as an alkaline solution of lithium hydroxide is produced.

Question 19

When is hydrogen produced in a reaction?

Answer 19

When a metal reacts with water or a dilute acid.

Question 20

What are native metals?

Answer 20

Metals found in the crust naturally, which are unreactive such as gold.

Question 21

What is an ore?

Answer 21

When a rock contains a high enough percentage of metal atoms to make it profitable..

Question 22

What are bases?

Answer 22

Substances that neutralize acids.

Question 23

What is the difference between soluble and insoluble bases?

Answer 23

Soluble bases are known as alkalis whereas insoluble bases are usually metal oxides or metal carbonates where the product won’t dissolve.

Question 24

When does neutralization occur?

Answer 24

When H+ ions are removed from a solution usually by OH- ions.

Question 25

When is a solution neutral?

Answer 25

When the concentration of OH- ions is equal to H+ ions.

Question 26

What is an electrolyte?

Answer 26

The compound on which electrolysis is carried out. They are always ionic compounds.