paper 1 2023

Question 1

3.1

Give an equation for the reaction between phosphorus and an excess of oxygen.

Answer 1

P4 + 5 O2 → P4O10

Question 2

3.2

Give an equation for the reaction between sulfur dioxide and water.

Answer 2

SO2 + H2O → H2SO3

Question 3

3.4

Give an equation for the reaction of magnesium with steam. State one observation made.

Answer 3

• Mg + H2O → MgO + H2
• White solid/white powder OR (Bright) white flame

Question 4

3.5

Give an equation to show how an excess of magnesium oxide reacts with phosphoric acid (H3PO4).

Answer 4

3 MgO + 2 H3PO4 → Mg3(PO4)2 + 3 H2O

Question 5

4.4

The equilibrium mixture is compressed into a smaller volume. Deduce the effect, if any, of this change on the equilibrium yield of oxygen and on the value of Kp

Answer 5

• yeild effect- Decrease
• Kp value- No change

Question 6

4.5

The equilibrium mixture is allowed to reach equilibrium at a lower temperature. Explain why the equilibrium yield of oxygen decreases.

Answer 6

• M1 forwards Reaction is endothermic
• M2 Equilibrium shifts/moves in backwards direction to oppose the decrease in temp

Question 7

6.2

descibe how to make standard solution

Answer 7

• M1 Transfers the solution to a volumetric/graduated flask
• M2 Add washings using distilled water and make up to the graduation mark/250 cm3
• M3 Invert many times / shake to mix

Question 8

6.3

Before the first titration pipette is rinsed with a small volume of the barium hydroxide solution. State why it is good practice to rinse the pipette in this way.

Answer 8

• So that the titration is done with known concentration of Ba(OH)2

Question 9

6.4

Hydrochloric acid is added to the burette using a funnel. State why it is good practice to remove the funnel from the burette before the titration.

Answer 9

Drops of acid could fall into the burette

Question 10

9.1

Give the equation, including state symbols, for the formation of Sr + ions from Sr atoms by electron impact.

Answer 10

Sr(g) + e– → Sr +(g) + 2 e–

Question 11

9.3

how are ions detected

Answer 11

each ion gains an electron (generating a current)

Question 12

9.3

How relative abundance is determined

Answer 12

current is proportional to abundance