2011 Chemistry Neco Theory Questions

1. The following materials were provided for a titration experiment: Solution A which contains 10.9gdm-3 of dibasic acid H2Y, solution B containing 1.0 moldm-3 of sodium trioxocarbonate (IV), distilled water, 250cm3 pippette, and a bottle each of methyl orange and phenolphthalein indicators.

a. What would be the colour of
i. Methyl orange in solution A and B
ii. Phenolphthalein in solution A and B
iii. Which of the two indicators will be more suitable for the titration? Give reasons

b. List THREE measures to be taken during titration experiments to ensure accurate results.

c. 22.5cm3 of Solution A neutralized 25.0cm3 of 0.10moldm-3 solution of sodium trioxocarbonate (IV). Calculate the

i. Concentration of solution A in moldm-3
ii. Molar mass of the acid H2Y

The equation for the reaction is Na 2 CO3
d. Name ONE reagent that is kept inside amber coloured bottle and state a reason for doing so.

The following heat tests were carried out on given samples of salts. Give the possible observations and inferences. The observation given must include the confirmatory given must include the confirmatory test

iii. Place the following substances into their correct position using the alphabets in the Venn diagram above.

i. Zn (OH) Cl

ii. CH₃COOH

iii. AlCl₃

iv. NaHSO₄