Chemical Changes (C5-6)

Question 1

How can you work out pH from the concentration of H+ ions?

Answer 1

0.1 = 1
0.01 = 2
0.001 = 3 etc…

Question 2

How do you extract elements below carbon in the reactivity series?

Answer 2

Carbon reduction

Question 3

How do you extract elements above carbon in the reactivity series?

Answer 3

Electrolysis

Question 4

What is the ionic charge of carbonate?

Answer 4

CO(3) 2-

Question 5

What is the ionic charge of ammonium?

Answer 5

NH(4) +

Question 6

What is the ionic charge of sulphate?

Answer 6

SO(4) 2-

Question 7

What are the ionic charges of transition metals?

Answer 7

The Roman numeral next to it

Question 8

What is a strong acid?

Answer 8

An acid that completely ionises in aqueous solutions

Question 9

What is a weak acid?

Answer 9

An acid that partially ionises in aqueous solutions

Question 10

Why do ions have to be molten / aqueous to carry charge?

Answer 10

Solids can’t carry charge because their ions are fixed in position. Ions that are dissolved in water or molten are free to move and can carry charge

Question 11

What is produced at the anode? (aqueous solutions)

Answer 11

Oxygen, unless there is a halide ion present

Question 12

What is produced at the cathode? (aqueous solutions)

Answer 12

The least reactive ion

Question 13

Which type of redox reaction occurs at the anode and why?

Answer 13

Oxidation - negative ions lose electrons

Question 14

What type of redox reaction occurs at the cathode and why?

Answer 14

Reduction - positive ions gain electrons

Question 15

What’s the formula for sulphuric acid?

Answer 15

H2SO4

Question 16

What’s the ionic charge of nitrate?

Answer 16

NO(3) -

Question 17

What’s the equation for a neutralisation reaction?

Answer 17

H+(aq) + OH-(aq) —> H20(l)

Question 18

Write a method for creating a soluble salt from copper oxide and sulfuric acid

Answer 18

1. Heat a beaker of sulfuric acid over a Bunsen burner
2. Using a spatula, add copper oxide and stir until it dissolves
3. Repeat until the copper oxide is in excess
4. Filter solution with filter paper and a funnel
5. Pour into an evaporating dish
6. Heat until crystals start to form
7. Leave to crystallise overnight
8. Pat crystals dry with a paper towel

Question 19

Write a method for a titration of HCl with NaOH

Answer 19

1. Pour some of the known concentration of alkali (NaOH) into a beaker
2. Using a volumetric pipette, measure 25cm^3 and transfer into a conical flask
3. Add methyl orange indicator
4. Fill a burette with the unknown concentration of acid (HCl) and record the volume added
5. Place the conical flask on a white tile under the burette (for more obvious colour change)
6. Open the burette tap and swirl the flask until the indicator turns red
7. Close the tap and calculate the volume of acid poured out

Question 20

Write a method for electrolysis of copper chloride

Answer 20

1. Pour 50cm^3 of copper chloride solution into a large beaker
2. Put the Petri dish lid on top and put the two carbon rods through the holes, making sure that they don’t touch each other
3. Attach crocodile clips to the rods and connect the wires to a power supply
4. Switch on the power and record observations