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- A student investigated the effect of an electric current by passing it through some substances. The student used inert electrodes, and connected a bulb to the circuit. The table below shows the substances used and their states.
- In which experiment did the bulb not light? (1 mark)
- Explain your answer in (a) above. (2 marks)
- An alkanol has the following composition by mass: hydrogen 13.5%, oxygen 21.6% and carbon 64.9%
- Determine the empirical formula of the alcohol(C=12.0; H=1.0’ 0=16.0). (2mks)
- Given that empirical formula and the molecular formula of the alkanol are the same,draw the structure of the alkonol
- The figure below shows an energy cycle.
- Give the name of the enthalpy change ΔH1. (1 mark)
- Determine the value of ΔH3.(2 marks)
- The set up below was used to investigate the reaction between dry hydrogen gas and copper
- Name substance A.(1 mark)
- State the observation made in the combustion tube. (1 mark)
- Explain the observation stated in (b) above. (1 mark)
- Starting with sodium metal, describe how a sample of crystals of sodium hydrogen carbonate may be prepared. (3 marks)
- Ammonium ion has the following structure Label on the structure:
- covalent bond;
- coordinate (dative) bond.
- When 8.53g of sodium nitrate were heated in an open test-tube, the mass of oxygen gas produced was 0.83 g . Given the equation of the reaction as 2NaNO3 (s) -> 2NaNO2 (s) + O2 (g)
Calculate the percentage of sodium nitrate that was converted to sodium nitrite. (Na = 23.0, N = 14.0, O = 16.0) (3 marks)
- Aluminium is both malleable and ductile.
- What is meant by?
- Malleable: (1 mark).
- Ductile (1 mark)
- State One use of aluminium based on:
- malleability (½ marks)
- ductility (½ marks)
- The diagram below represents the set-up that was used to prepare and collect hydrogen chloride gas in the laboratory.
- State the purpose of concentrated sulphuric (VI) acid in the wash bottle. (1 mark)
- Write an equation for the reaction between dry hydrogen chloride gas and heated iron. (1 mark)
- Iron (III) oxide was found to be contaminated with copper (II)sulphate. Describe how a pure sample of iron (III) oxide can be obtained. (3 marks)
- Complete the nuclear equation below: (1 mark)
- The half-life of I is 8 days. Determine the mass of 131I remaining if 50 grammes decayed for 40 days (1 mark)
- Give one harmful effect of radioisotopes. (1 mark)
- During an experiment, chlorine gas was bubbled into a solution of potassium iodide.
- State the observations made. (1 mark)
- Using an ionic equation, explain why the reaction is redox. (2 marks)
- Draw the structure of compound N formed in the following reaction.
- Give one use of compound N. (1mk)
- When fuels burn in the internal combustion engine at high temperature, one of the products formed is nitrogen (II) oxide.
- Write the equation for the formation of nitrogen (II) oxide. (1 mark)
- Give a reason why nitrogen (II) oxide is not formed at room temperature. (1 mark)
- Describe how formation of nitrogen (II) oxide in the internal combustion engine leads to gaseous pollution. (2 mark)
- Sodium hydroxide can be prepared by the following methods; I and II.
- Name one precaution that needs to be taken in method I. (1 mark)
- Give the name of process A. (1 mark)
- Give one use of sodium hydroxide. (1 mark)
- The atomic number of sulphur is 16. Write the electron arrangement of sulphur in the following: (2 marks)
- A compound whose general formula is M(OH)3 reacts as shown by the equation below.
- What name is given to compounds which behave like M(OH) 3 in the two reactions. (1 mark)
- Name two elements whose hydroxides behave like that of M. (2 marks)
- A water trough, aqueous sodium hydroxide, burning candle, watch class and a graduated gas jar were used in an experimental set up to determine the percentage of active part of air. Draw a labeled diagram of the set up at the end of the experiment.
- In an experiment on rates of reaction, potassium carbonate was reacted with dilute sulphuric (VI) acid.
- What would be the effect of an increase in the concentration of the acid on the rate of the reaction? (1 mark
- Explain why the rate of reaction is found to increase with temperature. (2 mark
- 60 cm3 of oxygen gas diffused through a porous partition in 50 seconds. How long would it take 60cm3 of sulphur (IV) oxide gas to diffuse through the same partition under the same conditions? (S = 32.0, 0 = 16.0) (3 marks)
- Draw and name the isomers of pentane.(3 marks)
- The set-up below was used to collect a dry sample of a gas. Give two reasons why the set-up cannot be used to collect carbon (IV) oxide gas. (2 marks)
- Given the following substances: wood ash, lemon juice and sodium chloride.
- Name one commercial indicator that can be used to show whether wood ash, lemon juice and sodium chloride are acidic, basic or neutral. (1 mark)
- Classify the substances in 15(a) above as acids, bases or neutral. (2 marks
- Describe how a solid sample of potassium sulphate can be prepared starting with 200cm3of 2M potassium hydroxide. (3 marks)
- Charcoal is a fuel that is commonly used for cooking. When it burns it forms two oxides.
- Name the two oxides. (2 marks)
- State one use of the two oxides. (1 mark)
- Hydrogen sulphide is a highly toxic and flammable gas. It is normally prepared in a fume chamber.
- Name two reagents that can be used to prepare hydrogen sulphide in the laboratory.(1 mark)
- One of the uses of hydrogen sulphide is to produce sulphur as shown in the following equation: 2H2S(g) + S02 (g) -> 3S(s) + 2H20(l)
Identify the reducing agent in this reaction and give a reason for your answer. (1 mark)
- Other than production of sulphuric (VI) acid, state one commercial use of sulphur.(1 mark)
- Describe an experimental procedure that can be used to extract oil from nut seeds. (2 marks)
- A mixture contains ammonium chloride, copper (II) oxide and sodium chloride. Describe how each of the substances can be obtained form the mixture. (3 marks)
- When a student was stung by a nettle plant, a teacher applied an aqueous solution of ammonia to the affected area of the skin and the student was relieved of pain. Explain. (2 marks)