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- The following table shows some properties of period three elements and their chlorides. Study it and answer the questions that follow.
a)Complete the table by filling...(Solved)
The following table shows some properties of period three elements and their chlorides. Study it and answer the questions that follow.
a)Complete the table by filling in the formula of the missing chlorides.
b)In terms of structure and bonding, explain the following observations:
i)The melting point of aluminium is higher than that of sodium.
ii)The melting point of chlorine is lower than that of sulphur.
iii)The melting point of aluminium chloride is lower than that of magnesium chloride.
c)Sodium chloride dissolves in water to form a neutral solution but aluminium chloride dissolves
to form an acidic solution. Explain this observation.
d)Generally, the first ionization energy increases across the period. Explain
e)Iron (III) oxide was found to be contaminated with magnesium chloride. Describe how a pure dry sample of iron (III) oxide can be obtained.
Date posted: November 1, 2019. Answers (1)
- The diagram below is a simplified apparatus for extraction of sodium. Study it and answer the
equations that follow:-(Solved)
The diagram below is a simplified apparatus for extraction of sodium. Study it and answer the
equations that follow:-
(a) Which substances come out at:- P & Q
(b) What is the role of the diaphragm
(c) Write the equation of the reaction forming sodium
Date posted: November 1, 2019. Answers (1)
- Heated iron forms iron (III) chloride when reacted with chlorine and iron (II) chloride when reacted with hydrogen chloride gas. Explain this difference.
(Solved)
Heated iron forms iron (III) chloride when reacted with chlorine and iron (II) chloride when reacted with hydrogen chloride gas. Explain this difference.
Date posted: November 1, 2019. Answers (1)
- The table below shows some properties of substances I, J, K and L.
Identify the substances with:
a)A metallic bond
b)A covalent bond
c)An ionic bond (Solved)
The table below shows some properties of substances I, J, K and L.
Identify the substances with:
a)A metallic bond
b)A covalent bond
c)An ionic bond
Date posted: November 1, 2019. Answers (1)
- Nitrogen and oxygen gases react according to the equation given below;
a)Explain the effect of increasing temperature on the yield of nitrogen (II) oxide.
b)If 200cm3...(Solved)
Nitrogen and oxygen gases react according to the equation given below;
a)Explain the effect of increasing temperature on the yield of nitrogen (II) oxide.
b)If 200cm3 of nitrogen were used, determine the volume of nitrogen (II) oxide gas produced.
Date posted: November 1, 2019. Answers (1)
- A current of 3A was passed through fused aluminium oxide for 10minutes. Calculate the mass of Aluminium obtained at one electrode (Al = 27.0, IF...(Solved)
A current of 3A was passed through fused aluminium oxide for 10minutes. Calculate the mass of Aluminium obtained at one electrode (Al = 27.0, IF = 96500C)
Date posted: November 1, 2019. Answers (1)
- When air is bubbled through pure water of pH 7.0, the pH drops to 6.0. Explain. (Solved)
When air is bubbled through pure water of pH 7.0, the pH drops to 6.0. Explain.
Date posted: November 1, 2019. Answers (1)
- The table below shows condensed structural formulae of some organic compounds. Use it to answer the questions that follow.
a)State and explain the difference in the...(Solved)
The table below shows condensed structural formulae of some organic compounds. Use it to answer the questions that follow.
a)State and explain the difference in the boiling points of compounds A and E.
b)Write an equation to show the reaction between compounds B and E and give the name of the
product formed.
Equation.
Name of product:
c)Give one chemical test that can be used to identify compound C.
Date posted: November 1, 2019. Answers (1)
- A series of experiments were done using 0.1g pieces of magnesium and dilute hydrochloric acid.
The following results were obtained.
a)Sketch the curve obtained when the...(Solved)
A series of experiments were done using 0.1g pieces of magnesium and dilute hydrochloric acid.
The following results were obtained.
a)Sketch the curve obtained when the volume of gas produced was plotted
against time for each of the experiments and label each as 1, 2 or 3.
b)Write an equation for the reaction that took place
Date posted: November 1, 2019. Answers (1)
- The sketch below shows a graph of temperature against time obtained when a gaseous substance was cooled.
Explain what happens to the gaseous substance between:
a)T and...(Solved)
The sketch below shows a graph of temperature against time obtained when a gaseous substance was cooled.
Explain what happens to the gaseous substance between:
a)T and U
b)U and V
c)V and W
Date posted: November 1, 2019. Answers (1)
- The flow chart below illustrates the extraction of Zinc. Study it and answer the questions that follow:(Solved)
The flow chart below illustrates the extraction of Zinc. Study it and answer the questions that follow:
a) Name:-
i) Gas Q
ii) Liquid R
(iii) Residues S
b) Name the sulphide ore used
c) Before the ore is roasted, it is first concentrated;
(i) Explain why it is necessary to concentrate the ore
(ii) Explain briefly the process of concentrating the ore
d) Write an equation for the reaction that takes place in the:-
(i) Roaster
(ii) Reaction chamber
(e) (i) Name one major impurity present in the sulphide ore used
(ii) Write an equation to show how the impurity in (e)(i) above is removed
f) Given that the sulphide ore contains only 45% Zinc sulphide by mass, calculate :
(i) The mass in grams of Zinc sulphide that would be obtained from 250kg of the ore.
(ii) The volume of Sulphur (IV) oxide that would be obtained from the mass of sulphide
ore at room temperature and pressure
(Zn = 65.4, S = 32.0, O= 16.0, I mole of gas occupies 24.0 liters at r.t.p)
Date posted: November 1, 2019. Answers (1)
- 100cm3 of propane diffuses through a porous plug in 20 seconds. How long would it take 80cm3
of methane gas to diffuse through the same...(Solved)
100cm3 of propane diffuses through a porous plug in 20 seconds. How long would it take 80cm3
of methane gas to diffuse through the same plug? (C = 12.0, H = 1.0)
Date posted: November 1, 2019. Answers (1)
- A copper spoon was coated with silver metal as shown below.
i)Write an equation for the reaction that occurs at the copper spoon cathode.
ii)How many grams...(Solved)
A copper spoon was coated with silver metal as shown below.
i)Write an equation for the reaction that occurs at the copper spoon cathode.
ii)How many grams of silver would be deposited on the spoon in two hours using steady current of 0.03A? (1 F = 96500C, Ag = 108.0)
Date posted: November 1, 2019. Answers (1)
- State and explain the substance that acts as the acid in the forward reaction.
(Solved)
State and explain the substance that acts as the acid in the forward reaction.
Date posted: November 1, 2019. Answers (1)
- The diagram below is a flow chart for the extraction of copper. Study it and answer the questions that follow:(Solved)
The diagram below is a flow chart for the extraction of copper. Study it and answer the questions that follow:
(a) Write the formula of the major ore of copper metal
(b) Name process II
(c) Give an equation for the reaction that occurs in stage III
(d) Explain what happens in stage IV
(e) Write half cell equations occurring at the anode and cathode in stage VII
(f) Draw a simple diagram showing the set-up that is used in electrolytic purification of copper
Date posted: November 1, 2019. Answers (1)
- Aluminium is the most abundant metal in the earth crust and it is widely extracted for its wide range of uses.
(i) Name one major ore...(Solved)
Aluminium is the most abundant metal in the earth crust and it is widely extracted for its wide range of uses.
(i) Name one major ore of aluminium and give its formula
(ii) Name two main impurities found in the ore
(iii)Aluminium oxide is heated first before it is electrolysed. Explain
Date posted: November 1, 2019. Answers (1)
- The flow chart below shows steps used in the extraction of zinc from one of its ores.(Solved)
The flow chart below shows steps used in the extraction of zinc from one of its ores.
(a) Name the process that is used in step 2 to concentrate the ore
(b) Write an equation for the reaction which takes place in step 3
Date posted: November 1, 2019. Answers (1)
- Study the information provided:-(Solved)
Study the information provided:-
Explain why the melting point of the oxide of W is lower than that of the oxide of Z
Date posted: November 1, 2019. Answers (1)
- Name the following compounds using IUPAC system
(i) CCl4
(ii) HOCl(Solved)
Name the following compounds using IUPAC system
(i) CCl4
(ii) HOCl
Date posted: November 1, 2019. Answers (1)
- The stages shown in the following diagram can be used to extract zinc from its oxide.
Name the stage and the process taking place in it:-(Solved)
The stages shown in the following diagram can be used to extract zinc from its oxide.
Name the stage and the process taking place in it:-
Stage 1
Stage 2
Stage 3
Date posted: November 1, 2019. Answers (1)