O-LevelChemistryAtomic Structure5070/22 · Oct/Nov 2021 · Q710 Marks
Sodium is a metal in Group I of the Periodic Table. Diamond (carbon) is a non-metal which is a good conductor of heat.
- (a)State two differences in the physical properties of sodium and diamond. 1 2[2]
- (b)An ion of sodium has the symbol 23 11 Na+ Deduce the number of protons, neutrons and electrons in this ion. number of protons number of neutrons number of electrons[3]
- (c)Sodium reacts with nitrogen to form sodium nitride. Complete the equation for this reaction. Na + Na3N[1]
- (d)(i)When carbon is heated with steam in a closed container an equilibrium mixture is formed. C(s) + H2O(g) ⇌ CO(g) + H2(g) The forward reaction is endothermic. Describe and explain the effect, if any, on the position of equilibrium when the temperature is increased.[2]
- (d)(ii)Describe and explain the effect, if any, on the position of equilibrium when the pressure is decreased.[2]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2021). The mark or mark type is shown in brackets.
- [2] Any two from:
- sodium conducts electricity / diamond does not conduct electricity (1)
- sodium malleable / diamond brittle (1)
- brittle (1)
- sodium ductile / diamond not ductile (1)
- sodium soft / diamond hard (1)
- [3] protons: 11 (1)
- neutrons: 12 (1)
- electrons: 10 (1)
- [1] 6Na + N2 → 2Na3N
- [2] equilibrium moves to the right / more product formed (1)
- (increasing the temperature) pushes the reaction in the direction of absorbing energy / (increasing the temperature) pushes the reaction in the direction of the endothermic reaction (1)
- [2] equilibrium moves to the right / more product formed (1)
- more gas molecules on right than on left / more moles of gas on right than on left / when pressure decreased reaction moves in direction of more gas molecules (1)
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