1) Calculate the percentage by mass of sulphur in CuSO4.5H2O.

2) Calculate the molar mass (g mol-1) of the following gases:

A: 0.32 of gas X occupies 48 cm3 at rtp

b) 0.355 g of gas Y occupies 120 cm3 at rtp

3) Stibnite is an ore containing 5% by mass of the compound antimony sulphide, Sb2S3. Tgh metal is produced by reduction of antimony sulphide by iron.

Sb2S3 + 3Fe → 2Sb + 3FeS

a) Calculate the number of moles of Sb2S3. In 680 Kg of stibnite, assuming the sample

contains 5% by mass of Sb2S3.

b) Calculate the maximum mass of antimony that could be obtained from 680 Kg of stibnite.

4) A solution of hydrochloric acid of volume 25.0 cm3 was pipetted onto a piece of marble which is calcium carbonate. When all action had ceased, 1.30g of the marble had dissolved. Find the concentration of the acid

Equation: CaCO3 + 2HCl  CaCl2 + CO2 + H2O

5)What volume of 0.1 moldm-3 hydrochloric acid would be required to dissolve 2.3 g of calcium carbonate?

Equation: CaCO3(s) + 2HCl(aq)  CaCl2(aq) + CO2(g) + H2O(l)

3 6)2.05 g of the carbonate of an unknown alkali metal (X2CO3) required 8.9 cm of 2.0 moldm-3 hydrochloric acid to completely dissolve it. What was the relative atomic mass of the metal and which metal was it?

Equation: X2CO3(s) + 2HCl(aq)  2XCl(aq) + CO2(g) + H2O(l) 7)Succinic acid has the formula (CH2)n(COOH)2 and reacts with dilute sodium hydroxide as follows: (CH2)n(COOH)2 + 2NaOH  (CH2)n(COONa)2 + 2H2O 2.0 g of succinic acid were dissolved in water and the solution made up to 250 cm3. This solution was placed in a burette and 18.4 cm3 was required to neutralise 25 cm3 of 0.1 moldm-3 NaOH.

a) Calculate the number of moles of NaOH used in the reaction

b) Calculate the number of moles of succinic acid which were neutralised.

c) Calculate the molar mass of succinic acid.

d) Deduce the value of n. 8. Sodium carbonate exists in hydrated form, Na2CO3.xH2O, in the solid state. 3.5 g of a sodium carbonate sample was dissolved in water and the volume made up to 250 cm3. 25.0 cm3 of this solution was titrated against 0.1 moldm-3 HCl and 24.5 cm3 of the acid were required.:

Na2CO3 + 2HCl  2NaCl + CO2 + H2O

a) Calculate the number of moles of hydrated calcium carbonate

b) Calculate the amount in g of anhydrous salt.

c) Calculate the amount in g of water of crystallisation

d) Calculate the value of x

3 9) 25 cm of a sample of vinegar (CH3COOH) was pipetted into a volumetric flask and the volume was made up to 250 cm3. This solution was placed in a burette and 13.9 cm3 were required to neutralise 25 cm3 of 0.1 moldm-3 NaOH. Calculate the molarity of the original vinegar solution and its concentration in gdm-3, given that it reacts with NaOH in a 1:1 ratio.

1) 12.08%

2) A 160 gmol-1

B= 71 g mol-1

3)a= 10 mol

B= 24.4 kg

4. 1.04 moldm-3

5. 459 cm3

6. 85.2, Rb

7. x = 10

8.1.80 oldm-3, 108 gdm-3 8. n = 2