A-LevelChemistryGroup 29701/41 · May/June 2018 · Q47 Marks
Describe what you would see when calcium and barium are heated separately with oxygen. calcium barium
- (a)Describe what you would see when calcium and barium are heated separately with oxygen. calcium barium[2]
- (b)The decomposition temperatures of the Group 2 carbonates vary down the group. State and explain the variation in the decomposition temperatures.[3]
- (c)Magnesium carbonate was heated in an open test-tube. It was difficult to see whether a thermal decomposition reaction took place. Explain why.[2]
Mark scheme
Marking points from the official mark scheme (May/June 2018). The mark or mark type is shown in brackets.
- [1] calcium - red flame
- [1] barium - green flame
- [1] the temperature increases down the group
- [1] ionic radius increases / charge density decreases down the group
- [1] decreasing distortion / polarisation or decreasing weakening of bonds
- [1] of the anion / the CO32- ion
- [1] the gas is colourless / looks like air / cannot be seen
- [1] appearance of solid doesn't change / white solid becomes white solid
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