(a) Brine usually contains soluble calcium and magnesium salts. Explain how sodium carbonate is used to purify brine.
b) The diagram below represents a diaphragm cell used to electrolysed pure brine
i) Write the equations for the reactions that take place at
I Product at U
II Another material that can be used instead of titanium
III The impurity present in the product at U
iii) State two functions of the diagram
c) Give one industrial use of the product at U.
a) Crude oil is a source of many compounds that contain carbon and hydrogen only.
(i) Name the processes used to separate the components of crude oil
(ii) On what two physical properties of the above components does the separation depend?
b) Under certain conditions, hexane can be converted to two products.
The formula of one of the products is C3H3
(i) Write the formula of the other product
(ii) Describe a simple chemical reaction to show the difference between the two products formed in (b) above.
c) Ethane, C2H2 is another compound found in crude oil.
One mole of ethane was reacted with one mole of hydrogen chloride gas and a product p1 and was formed. P1 was then reacted with excess hydrogen gas to form p2. Draw the structures p1 and p2.
d) The set-up below was used to prepare and collect ethane gas. Study it and answer the questions that follow.
(i) Name the substance T
(ii) Give the property of ethane that allows it to be collected as shown in the set up.
e) One of the reactions undergone by ethane is addition polymerization. Give the name of the polymer and one disadvantage of the polymer it forms. (2 marks)
Name the polymer.
Disadvantage of the polymer
The flow chart below shows some reactions starting with lead (II) nitrate. Study it and answer the questions that follow.
(i) State the condition necessary in step 1.
I Reagent K
II Gas Q
III Acidic products S and R
I The formula of the complex ion formed instep 3.
II The equation of the reaction in step 4
b) The use of materials made of lead in roofing and in water pipes is being discouraged
(i) Two reasons why these materials have been used in the past.
(ii) One reason why their use is being discouraged
c) (i) The reaction between lead (II) nitrate and concentrated sulphuric acid starts but stops immediately. Explain
a) at 250°C , 50g of potassium were added to 100gm of water to make a saturated solution. What is meant by a saturated solution?
b) The table below gives the solubilities of potassium nitrate at different temperatures.
(i) Plot graph of the solubility of potassium nitrate (vertical axis) against temperature
(ii) Using the graph:
I Determine the solubility of potassium nitrate at 15°C
II Determine the mass of potassium nitrate that remained undissolved given that 80g of potassium nitrate were added to 100cm3 of water and warmed to 40°C.
c) Determine the molar concentration of potassium nitrate at 15°C
(Assume there is no change in density of water at this temperature) (K = 39. 0; N= 14.0; O = 16.0)
a) The diagram below illustrates how Sulphur/extracted by the Frisch process.
Label the pipe through which superheated water is pumped in
b. The equation below shows the oxidation of sulphur dioxide to sulphur trioxide in the contact process.
(i) Name one catalyst for this reaction
(ii) State and explain the effect on the yield of sulphur trioxide when:
I The temperature increased
II The amount of oxygen is increased
(iii) Describe how sulphur trioxide is converted to sulphuric acid in the contact process.
(c) State two disadvantages of having sulphur dioxide in the environment
(d) Ammonia sulphate is a fertilizer produced by passing ammonia gas into concentrated sulphuric acid.
(i) Write the equation for the reaction
(ii) Calculate the mass in Kg of sulphuric acid required to produce 25kg of the fertilizer (S = 32.0; O= 16.0; N = 1.0)
a) The set-up below was used to collect gas F, produced by the reaction between water and calcium metal.
(i) Name gas F
(ii) At the end of the experiment, the solution in the beaker was found to be a weak base. Explain why the solution is a weak base.
(iii) Give one laboratory use of the solution formed in a beaker.
(b) The scheme below shows some reactions starting with calcium oxide. Study it and answer the questions that follow.
(i) Name the reagents used in steps 2 and 4
Step 2 ……….
Step 4 ……….
(ii) write an equation for the reaction in step 3.
(iii) Describe how a solid sample of anhydrous calcium sulphate is obtained in
a) The table below shows properties of chlorine, bromine and iodine.
Complete the table by giving the missing information in (i),(ii) and (iii)
b) Chlorine gas is prepared by reacting concentrated hydrochloric acids with manganese (iv) oxide.
i) Write the equation for reaction between concentrated hydrochloric acid and manganese (iv) oxide.
ii) What is the role of manganese (Iv) oxide in this reaction
c) i) Iron (II) chloride reacts with chlorine gas to form substance E.
Identify substance E
ii) During the reaction in c(i) above,6.30g of iron chloride were converted to 8.06 of substance E. Calculate the volume of chlorine used.(Cl = 35.5, Molar gas volume at room temperature = 24000cm3, Fe =56 )
d) Draw and name the structure of the compound formed when excess chlorine gas is reacted with ethane gas.
e) Give the industrial use of chlorine
Apiece of chromatography paper was spotted with coloured inks obtained from pens labeled 1 to 6. The diagram below shows the spots after the chromatogram was developed.
a) Which two pens contained in the same pigment?
b) Which pens contained only one pigment
c) According to the chromatogram, which pigments are present in the ink of pen number 6.
(a) 4 and 5 blue and Green (full) H2SO4 (aq) is on electrolyte
(b)2 and 3 yellow and red
(c)Yellow and red
4 – Blue
5 – Green
2 – Yellow
3 – Red award it the colour is tied to the number
Carbon dioxide can be dissolved in water under pressure to make an acidic solution.
a) What is meant by an acidic solutions?
b) aqueous lead (II) nitrate reacts with the acidic solution to form a precipitate.
Write anionic equation for the reaction.
The react between a piece of magnesium ribbon with excess 2m hydrochloric acid was investigated at 25°C by measuring the volume of hydrogen gas produced as the reaction progressed. The sketch below represents the graph that was obtained.
a) Name one piece of apparatus that may be used to measure the volume of hydrogen gas produced.
b) On the same diagram, sketch the curve that would be obtained if the experiment when excess chlorine gas was bubbled into hot concentrated sodium hydroxide, the following reaction occurred.
In which product did chorine undergo oxidation? Explain
State two factors which determine the stability of an isotope.
Maurice Atika is a teacher and a netprenuer.