A-LevelChemistryGroup 29701/42 · May/June 2018 · Q48 Marks
Write an equation, including state symbols, for the reaction that takes place when a sample of anhydrous calcium nitrate, Ca(NO3)2, is heated strongly in a test-tube.
- (a)(i)Write an equation, including state symbols, for the reaction that takes place when a sample of anhydrous calcium nitrate, Ca(NO3)2, is heated strongly in a test-tube.[2]
- (a)(ii)Describe what will be seen during this reaction.[2]
- (b)Describe and explain how the solubility of the Group 2 sulfates varies down the group.[4]
Mark scheme
Marking points from the official mark scheme (May/June 2018). The mark or mark type is shown in brackets.
- [1] 2Ca(NO3)2 → 2CaO + 4NO2 + O2
- [1] correct state symbols: (s), (s), (g), (g)
- [1] brown gas / fumes / vapour
- [1] white solid / residue (stays the same)
- [1] solubility decreases (down the group)
- [1] ∆Hlatt and ∆Hhyd decrease / both become less exothermic / less negative
- [1] ∆Hlatt decreases / becomes less exothermic by a smaller extent ora
- [1] ∆Hsol becomes less exothermic / less negative ora
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