Page 294 - Chemistry

(ii) Highest temp- lowest temp (from graph)
(d) 50x{[ac(ii)] x 4.2 = ans. D
(e) No. of moles of T used = c(i) x 1
1000
= ans. (e)
(f) No. of moles used
NaOH + HCl NaCl + H 2O
Mole ratio 1:1
= ans (e) = ans (f)

(g) and (f) moles liberate (and d) J
1 mole and (d) x 1
Ans (f) x 1000
= -Ans (g) KJmole-1

3.
Observation Inference
-
(a) Brown gas formed ½ NO 3 present ½
Blue litmus paper turns red/red litmus
paper remains red
(b) Partly dissolves/blue ppt do not Soluble and insoluble salt
dissolve ½
2+
3+
(c) (i) Partly soluble in excess Al / Pb /Zn 2+
2+
(ii) Yellow ppt Pb
2-
(d) (i) Effervescence CuO 3 suspected
(ii) Blue ppt, insoluble in excess ½ Cu2+ suspected
(e) Blue ppt, dissolves ½ Cu2+ confirmed
½
Deep blue solution
½

RACHUONYO DISTRICT
½

3
1. a) Moles of Hcl present in 50cm = 50x1 = 0.05 moles
1000

i) Complete table (1 mark)
- 3 titrations done-
- 2 titrations done
- 1 titration done
NB: Penalise ½ mark to a max of ½ mark for;
- inverted table
- wrong arithmetic
- burette readings beyond 50 cm 3 except where explained
- Unrealistic (below 1 cm3)

ii) Use of decimals (1 mark)
- 1d.p or 2 d.p throughout
nd
- for 2 d.p the 2 digit is either 0 or 5 otherwise penalize fully

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