in an experiment, soap solution was added to three separate samples of water. The table below shows the volumes of the soap solutions required to form lather with #1000cm^3# of each sample of water before and after boiling.
a) Which water sample is likely to be soft? Explain.
(b) Name the cause of change in the volume of soap solution used in sample III (Answered) The table shows how solubility of some substances in water varies with temperature.
Which of the above substances is likely to be a gas? Explain. (Answered) Explain the following observation. Chloride dissolves in water to form an electrolyte while the same chloride dissolves in methylbenzene to form a non-electrolyte. (Answered) Study the chart below and answer the questions that follow:
(a) Identify:
(i) The metal ions in solution K
(ii) The white precipitate L
(b) What property of the white precipitate L is illustrated by step I and II? (Answered) In an equation below, identify the reagent that acts as a base. Give a reason (Answered) Study the scheme below and answer the questions that follows.
(a) Write the formula of the cation present in solution F.
(b) What property of chlorine is shown in step I.
(c) Write an equation for the reaction which occur in step III. (Answered) What would be observed if soap solution was added dropwise to a sample of the water after the addition of the calcium hydroxide? Give a reason. (Answered) #90cm^3# of 0.01M calcium hydroxide were added to a sample of water containing 0.001 moles of calcium hydrogen carbonate.
(a) Write an equation for the reaction which took place
(b) Calculate the number of moles of calcium ions in #90cm^3# of 0.01M calcium hydroxide. (Answered) (a) Give the formula of an oxide which reacts with both dilute hydrochloric acid and hot concentrated sodium hydroxide
(b) Give the formulae of the products formed when oxide in (a) above reacts with excess hot concentrated sodium hydroxide (Answered) Study the information in the table and answer the question below the table.
Describe how a solid sample of substance A could be obtained from a solid mixture of A and B (Answered) A sample of water drawn from a river passing through an agricultural district was divided into two portions. The first portion gave a white precipitate when acidified barium chloride was added. The second portion when warmed with aqueous sodium hydroxide gave a colourless gas which turned a moist red litmus paper blue.
(a) Identify the ions present in the river water.
(b) Suggest the possible (Answered) The scheme below shows some reaction sequence starting with solid N.
(a) Identify solid N
(b) Write the formula of the complex ion present in solution Q (Answered) A bee-keeper found that when stung by a bee, application of a little solution of sodium hydrogen carbonate helped to relieve the irritation from the affected area. Explain. (Answered) The column below was used to soften hard water
(i) Explain how hard water was soften as it passed through the column.
(ii) After sometime the material in the column is not able to soften hard water. How can the material be reactivated?
(b) Give one advantage of using hard water for domestic purposes. (Answered) The table below shows the solubility of a salt at various temperatures
What would happen if a sample of a saturated solution of the salt at #40^0#C is heated to #80^0#C? Explain (Answered) State and explain one disadvantage of using hard water in boilers. (Answered) When solid magnesium carbonate was added to a solution of hydrogen chloride in methylbenzene, there was no apparent reaction. On addition of water to the resulting mixture, there was vigorous effervescence. Explain these observations. (Answered) The table below shows the tests carried out on separate samples of water drawn from a well and the results obtained.
(a) Identify the cation and the anion present in the water.
(b) Write an ionic equation for the reaction which takes place in test (iii) (Answered) Sample solutions of salts were labeled as I, II, III and IV. The actual solutions, not in that order , are lead nitrate, zinc sulphate, potassium chloride and calcium chloride.
(a) When aqueous sodium carbonate was added to each sample separately, a white precipitate was formed in I, III and IV
only. Identify solution II.
(b) When excess aqueous sodium was added to each sample separately, a white (Answered) a) A student was supplied with colourless liquid suspected to be water.
(i) Describe two chemical test that could have been used to show that liquid was water.
(ii) How could it have been shown that liquid was pure water? (Answered) State one cause of temporary hardness in water (Answered) How does distillation remove hardness from water (Answered) a) Study the information in the table below and answer the questions that follow. (the letter do not represent the actual symbols of the elements)
(i) What is the general name to the group in which elements P,Q, and R belong?
(ii) What is meant by ionization energy?
iii) Explain why element P have the highest ionization energy.
(iv) When a piece of element Q is placed on water it melts and a (Answered) a) What method can be used to separate a mixture of ethanol and propanol?
(b) (i) Explain how a solid mixture of sulphur and sodium chloride can be separated into solid sulphur and solid sodium chloride.
(ii) How can one determine if the solid sulphur is pure?
(c) The table below gives the solubilities of potassium bromide and potassium sulphate at #0^0C# and #40^0C#
(Answered) The following tests were carried out on three separate portions of a colourless solution R.
(a) From the information in test (i), name a cation which is not present in solution
(b) Identify a cation, which is likely to be present in solution S
(c) Write an ionic equation for the reaction which takes place in test(ii) (Answered) Give a reason why calcium hydroxide solution is used to detect the presence of carbon (IV) oxide gas while sodium hydroxide is not (Answered) Write an equation for the reaction that takes place when carbon (II) oxide gas is passed over heated Lead (II) oxide. (Answered) When extinguishing a fire caused by burning kerosene, carbon (IV) oxide is used in preference to water. Explain. (Answered) The diagram below represents a charcoal burner. Study it and answer the question that follows:
Write equations for the reactions taking place at I and I. (Answered) When excess carbon (II) oxide gas was passed over heated lead (II) oxide in a combustion tube, lead (II) oxide was reduced.
(a) Write an equation for the reaction, which took place.
(b) What observation was made in the combustion tube when the reaction was complete?
(c) Name other gas which could be used to reduce lead (II) oxide.
(Answered)
