Electrolysis

Question 1

An electric current is

Answer 1

A flow of electrons or ions

Question 2

Covalent compounds - conduct electricity?

Answer 2

NO- because the electrons are shared so are fixed in a certain position and are not able to move freely and conduct electricity.

Question 3

Ionic compounds - conduct electricity?

Answer 3

NOT when solid because the ions aren’t free to move

YES when molten or in solution because the ions can move freely

Question 4

Electrolysis is

Answer 4

A chemical change caused by passing on electric current through a compound that is either molten or in solution

Question 5

An Electrolyte is

Answer 5

A substance that undergoes electrolysis. Covalent compounds AREN’T because they don’t contain ions

Question 6

Anode

Answer 6

Positive electrode

Question 7

Cathode

Answer 7

Negative electrode

Question 8

PANC

Answer 8

Positive Anode Negative Cathode

Question 9

Charges of common positive ions (cations) - 1+

Answer 9

H+
Na+
Ag+
K+
Li+
NH4+

Question 10

Charges of common positive ions (cations) - 2+

Answer 10

Ba2+
Ca2+
Cu2+
Mg2+
Zn2+
Pb2+
Fe2+

Question 11

Charges of common positive ions (cations) - 3+

Answer 11

Fe3+

Al3+

Question 12

Testing for cations (Flame tests)

Answer 12

-Dip a platinum wire in Hydrochloric Acid and then into the solid, then into flame
Li+       Red flame
Na+      Strong orange flame
K+        Lilac flame
Ca2+    Brick red flame

Question 13

Testing for cations (Precipitation reactions)

Answer 13

-Add sodium hydroxide solution to the solution containing:

NH4+, Ammonia = No precipitate is formed but there will be a strong smell and when heated will turn damp litmus blue -ALKALINE
Cu2+, Copper = Blue precipitate (Copper ll hydroxide)
Fe2+, Iron ll = Green precipitate (Iron ll hydroxide)
Fe3+, Iron lll = Orange- brown precipitate (Iron lll hydroxide)

Question 14

Charges of common negative ions (anions) - 1-

Answer 14

Cl-
Br-
F-
I-
HCO3-
OH-
NO3-

Question 15

Charges of common negative ions (anions) - 2-

Answer 15

O2-
S2-
SO42-
CO32-

Question 16

Testing for anions (Chlorine, Bromine + Iodine)

Answer 16

-Add enough dilute nitric acid to make your solution (in water) acidic and then add sliver nitrate solution

Cl- = white precipitate (silver chloride)
Br- = pale cream precipitate (silver bromide)
I- = yellow precipitate (silver iodide)

Question 17

Testing for anions (Sulfates)

Answer 17

-Add enough dilute hydrochloric acid to make your solution (in water) acidic and then add barium chloride solution

SO42- = white precipitate (barium sulfate)

Question 18

Testing for anions (Carbonates)

Answer 18

-Add dilute nitric acid and look for bubbles of gas produced and collect, test for Carbon Dioxide

CO32- = bubbles of CO2

Question 19

Half equations at cathode

Answer 19

Cu2+(aq) + 2e- –> Cu(s)

Question 20

Half equations at anode

Answer 20

2I-(aq) –> I2(aq) + 2e-

Question 21

OILRIG

Answer 21

Oxidisation
Is
Loss of electrons
Reduction
Is
Gain of electrons

Question 22

Reducing agent

Answer 22

Substance that reduces something else (gives it electrons)

Question 23

Oxidising agent

Answer 23

Substance that oxidises something else (takes its electrons)

Question 24

Redox reaction

Answer 24

Where both oxidisation and reduction occur