Page 302 - Chemistry

White ppt, insoluble in nitric acid


ii) To the second portion, add Nitric acid, followed by lead(ii) Nitrate solution
Observations Inferences

2-

White ppt, ½mk insoluble in nitric acid SO confirmed

½ mk  4

iii) To the third portion, add a few drops until in excess N/B - All three mentioned - 1mk
Observations Inferences Any two mentioned - ½mk

White ppt, ½mk soluble in Al , Pb or Zn present - 0mk
2+
3+
2+
Only 1 mentioned
excess ½ mk


iv) To the fourth portion, add a few drops until in excess
Observations Inferences
White ppt, ½mk soluble in 2+

excess ½mk Zn confirmed


TRANSNZOIA WEST DISTRICT

Q1. i) Complete table with 3 titrations done – 1 mark
ii) Incomplete table with 2 titrations done – ½ mark
iii) Incomplete table with 1 titration done – 0 marks

Penalties
i) Wrong arithmetic
ii) Inverted table
iii) Unrealistic values

Penalize ½ mark for each to maximum of ½ mark

Decimals (1 mark)
Conditions
i) Accept either 1 or 2 decimal point constitently.
nd
ii) If 2 decimal point used the 2 decimal point can only be 0 or 5

Accuracy 1 mark
rd
Compare any litre values in the 3 row with the school value (sv)

Conditions
i) If within I 0.1cm3 of S.V 1 mark
ii) If within I 0.2 of S.V ½ mark
iii) Beyond I 0.2 of SV 0 mark

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