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Draw and name the isomers of pentane.
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In an experiment on rates of reaction, potassium carbonate was reacted with dilute sulphuric (VI) acid.
(a) What would be the effect of an increase in the concentration of the acid on the rate of the reaction? (b) Explain why the rate of reaction is found to increase with temperature.
ANSWERS
(a)The rate of reaction increases. This is because when the concentration is high: the number of collisions between particles is also high hence reacts faster,
(b)Increase in temperature results in increase in the kinetic energy of the particles. This makes particles move faster and collide frequently leading to faster rate of reaction.
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.
ANSWERS
A compound whose general formula is M(OH)3 reacts as shown by the equation below.
(a) What name is given to compounds which behave like M(OH) 3 in the two reactions.
(b) Name two elements whose hydroxides behave like that of M.
ANSWERS
(a) Amphoteric
(b)Lead, Zinc and Aluminium
The atomic number of sulphur is 16. Write the electron arrangement of sulphur in the following:
ANSWERS
Sodium hydroxide can be prepared by the following methods; I and II
(a) Name one precaution that needs to be taken in method I.
(b) Give the name of process A. (c) Give one use of sodium hydroxide.
ANSWERS
(a) Small piece of sodium metal (pea size) with a lot of water
Perform the experiment wearing goggles. (b) Electrolysis (c) Manufacture of paper (soften), soaps and detergents Fractional distillation of liquid air Extraction of aluminium metal Manufacture of bleaching agents eg NaOCl paper, textiles, oil refinery Making herbicides on weed killers Textile industry to soften
When fuels burn in the internal combustion engine at high temperature, one of the products formed is nitrogen (II) oxide.
(a) Write the equation for the formation of nitrogen (II) oxide. (b) Give a reason why nitrogen (II) oxide is not formed at room temperature. (c) Describe how formation of nitrogen (II) oxide in the internal combustion engine leads to gaseous pollution.
ANSWERS
(a)N2(g) + 02(g) 2NO(g)
(b)Nitrogen atoms in the molecule are joined by strong triple covalent bond that requires a lot of energy to break than provided at room temperature (c) Nitrogen (II) oxide reacts with oxygen in air to form nitrogen (IV) oxide that dissolves in water vapour causing acid rain.
(a)Draw the structure of compound N formed in the following reaction.
(b) Give one use of compound N.
ANSWERS
(b) Making synthetic fibres such as for: - Ropes
Blouses Stockings Undergarments Trousers
During an experiment, chlorine gas was bubbled into a solution of potassium iodide.
(a)State the observations made. (b)Using an ionic equation, explain why the reaction is redox
ANSWERS
(a)Solution turned from colourless to dark brown
Greenish yellow / pale green colour of Cl2 disappears Brown solution / black solid is deposited (b) Cl2 (aq) +2I – (aq) → I2 (aq)+2CI- (aq) Explanation; Iodine oxidation state changes from -1 to 0 hence oxidation while Cl2 0.5 changes from 0 to -1 hence reduction / increase is ON and decrease is ON or movement of electrons Cl2 gains e’s where lose
a)Complete the nuclear equation below:
(c)Give one harmful effect of radioisotopes.
ANSWERS
Instant / cause death
Cause cancer Cause gene mutation
Iron (III) oxide was found to be contaminated with copper (II) sulphate. Describe how a pure sample of iron (III) oxide can be obtained.
ANSWERS
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.
Write an equation for the reaction between dry hydrogen chloride gas and heated iron.
ANSWERS
It is a drying agent.
Fe(s) + 2HCI(g) → FeCI2(s) +H2(g)
Aluminium is both malleable and ductile.
(a)What is meant by? (i) Malleable: (ii)Ductile (b)State One use of aluminium based on: (i)malleability (ii)ductility
ANSWERS
(a) (i) Can be hammered into sheets.
(ii)Can be drawn into wires. (b)(i) Making of sufurias/ motor vehicle parts/ aeroplane parts,window / door flames, cups, plates, packaging materials, pans, making sheets/ roof. (ii)electricity cables/ wires.
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;
2NaNO 3 (s) -> 2NaNO 2 (s) + O 2 (g) Calculate the percentage of sodium nitrate that was converted to sodium nitrite. (Na = 23.0, N = 14.0, O = 16.0)
ANSWERS
Ammonium ion has the following structure
Label on the structure:
(a) covalent bond; (b) coordinate (dative) bond.
ANSWERS
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AuthorMaurice Atika is a teacher and a netprenuer. |
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