65.25 g sample of CuSO₄.5H₂O (M = 249.7) was dissolved in water to make 0.800 L of solution. What volume of this solution must be diluted with water to make 1.00 L of 0.100 M CuSO₄?

1.   3.27 ml
2. 383 ml
3. 209 ml
4. 65.25 ml
5. 306 ml.

(x)What volume of hydrogen gas will be produced when 1.3 g of zinc granules react completely with excess dilute sulphuric acid at s.t.p?

1. 130 cm³  
2.  224 cm³
3.  440 cm³ 
4.  220 cm³
5.  448 cm³

  In order to produce the greatest amount of hydrogen in a short time, one gram of magnesium ribbon should react with

1. 10 cm³ of 0.5 M sulphuric acid
2. 40 cm³ of 0.5 M acetic acid solution
3. 40 cm³ of 0.5 M sulphuric acid solution
4. 20 cm³ of 1 M sulphuric acid solution
5. 20 cm³ of 1 M acetic acid solution.

What will the molarity of a solution which contains 26.5 g of anhydrous sodium carbonate in 5 dm³ of solution?

1. 0.05 M
2. 0.25 M
3. 5.30 M
4. 0.025 M
5. 0.50 M

5. A certain compound with the molecular mass of 28 was analyzed and found to be composed of 0.6 g of carbon and 0.1 g of hydrogen.

(a) Work out its empirical formula and molecular formula.

(b) Classify the compound to its homologous series.

How many chlorine molecules are in 20 cm of chlorine gas at s.t.p?

Calculate the number of ions present in 5 g of copper II nitrate.

Define the following:

(i) Mole .

(ii) Molarmass .

112 dm³ of oxygen gas was collected at s.t.p when a sample of lead nitrate was completely decomposed by heat. Calculate the volume of nitrogen dioxide gas produced.

Copper can be obtained from the ore, copper pyrites (CuFeS2). The ore is heated in a limited amount of air giving the following reaction:

 4CuFeS2 + 11O 2 ? 4Cu + 2Fe 2 O 3 + 8SO2 .

(i) Calculate the maximum mass of copper that can be obtained from 367 kg of copper pyrites.

(ii) State why the gaseous product from this reaction must not be allowed to escape into the atmosphere.

 Calculate the volume of water which was produced when 1,120 cm³ of oxygen at s.t.p. was liberated during the decomposition of hydrogen peroxide. The density of water = 1.0 g/cm³ 

A student attempted to prepare hydrogen gas by reacting zinc metal with dilute sulphuric acid. In this experiment zinc metal granules of about 0.5 cm diameter and 0.20 moles of acid were used.

The rate of formation of hydrogen gas was found to be slow.

(a)Explain three ways in which the rate of formation of hydrogen gas could be increased.

(b)If the student wanted 36 cm³ of hydrogen gas at s.t.p, what amount of the acid would be required.

20 cm³ of a solution containing 7 g dm^-3 of sodium hydroxide were exactly neutralized by 25 cm³ of 0.10 M hydrochloric acid. Calculate the concentration of sodium hydroxide in moles per dm³.

  Aluminium reacts with oxygen to form aluminium oxide. How many grams of potassium chlorate would be heated to produce enough oxygen to form 5.1 g of aluminium oxide?

The preparation of chlorine gas can be represented by the following equation: 

 MnO₂ + 4HCl à MnCl₂ + 2H₂0 + Cl₂. How many moles of HCl are needed to react with 25 g of MnO₂?

  25 cm³ of 0.1 M HCl were neutralized by 23 cm³ of sodium hydroxide solution. Calculate the concentration of the alkali in grams per litre.

 Calculate the number of oxygen molecules and atoms in 0.5 moles of oxygen gas at room temperature.

  How many molecules are there in 11.2 litres of carbon dioxide at STP? 

  The preparation of chlorine gas can be represented by the following equation: MnO₂ + 4HCl ? MnCl₂ + 2H₂O + Cl₂. Calculate the number of moles of HCl which are needed to react with 20 g of MnO₂ and list two main chemical properties of chlorine gas.

10.   If 2.0 g of CaC0₃ were reacted with excess dilute HCI acid; (a) what volume of C02 would be given out at s.t.p?

(b)    Calculate the mass of C0₂ produced.   (7 marks)

5, (a) What is the molarity of a solution containing 10% by mass of calcium hydroxide in 0.5 dm3 of solution?

(i) Mole

(ii) Molecular weight (2 marks)

Calculate the total number of

(i) molecules in 0.18g of water

(ii) electrons present in 0.0001 moles of pure magnesium metal (4 marks)