- State two reasons why tin coating is used in food cans.(Solved)
State two reasons why tin coating is used in food cans.
Date posted: September 4, 2019. Answers (1)
- The molecular formula mass of gas A is 28 and its empirical formula is CH2.
(a) Determine the molecular formula of gas A (C = 12.0,...(Solved)
The molecular formula mass of gas A is 28 and its empirical formula is CH2.
(a) Determine the molecular formula of gas A (C = 12.0, H = 1.0).
(b) Write the equation of the reaction between A and 1 mole of chlorine gas.
Date posted: September 4, 2019. Answers (1)
- When the oxide of metal Z is heated in the presence of metal X, it is reduced.The oxide of metal X is reduced by metal...(Solved)
When the oxide of metal Z is heated in the presence of metal X, it is reduced.
The oxide of metal X is reduced by metal Y. Arrange the three metals in order of increasing reactivity.
Date posted: September 4, 2019. Answers (1)
- Study the information in the table below and answer the questions that follow:(Solved)
Study the information in the table below and answer the questions that follow:
A mixture containing 40g salt G and 120g salt Y in 100g of water at 80ºC was cooled to 50ºC.
(a) Which salt crystallized out? Give reason.
(b) Calculate the mass of the salt that crystallized out.
Date posted: September 4, 2019. Answers (1)
- Calculate the molar enthalpy of formation of ethyne (C2H2) given the following.(Solved)
Calculate the molar enthalpy of formation of ethyne (C2H2) given the following.
Date posted: September 4, 2019. Answers (1)
- Classify the following as either compounds or mixtures.(Solved)
Classify the following as either compounds or mixtures.
Date posted: September 4, 2019. Answers (1)
- Ethanol (CH3CH2OH) and dimethylether (CH3OCH3) are two compounds with the same molecular mass.
Explain why ethanol has a much higher boiling point (78.2ºC) than dimethylether (-24ºC).(Solved)
Ethanol (CH3CH2OH) and dimethylether (CH3OCH3) are two compounds with the same molecular mass.
Explain why ethanol has a much higher boiling point (78.2ºC) than dimethylether (-24ºC).
Date posted: September 4, 2019. Answers (1)
- Name the process that takes place when:
(i) Fats or oils are hydrolyzed using an alkali.
(ii) Sulphur is added to rubber in the manufacture of...(Solved)
Name the process that takes place when:
(i) Fats or oils are hydrolyzed using an alkali.
(ii) Sulphur is added to rubber in the manufacture of rubber tyres.
Date posted: September 4, 2019. Answers (1)
- In an experiment to investigate the conductivity of a substance a student used the set up shown below. The student noticed that the bulb did...(Solved)
In an experiment to investigate the conductivity of a substance a student used the set up shown below. The student noticed that the bulb did not light.
(i) What had been omitted in the set up?
(ii) Explain why the bulb lights up when the omission is corrected.
Date posted: September 4, 2019. Answers (1)
- Determine the oxidation number of:
(Solved)
Determine the oxidation number of:
(i) Manganese in KMnO4.
(ii) Chromium in 
Date posted: September 4, 2019. Answers (1)
- Describe how a solid sample of lead (II) sulphate would be prepared using the following reagents: dilute nitric (V) acid, lead (II) carbonate solid sodium...(Solved)
Describe how a solid sample of lead (II) sulphate would be prepared using the following reagents: dilute nitric (V) acid, lead (II) carbonate solid sodium sulphate and distilled water.
Date posted: September 4, 2019. Answers (1)
- Study the scheme below and answer the questions that follow.(Solved)
Study the scheme below and answer the questions that follow.
(i) Write down the formula of the yellow solid F.
(ii) What property of chlorine is shown in Step I?
(iii) Write an equation for the reaction which occurs in Step II.
Date posted: September 4, 2019. Answers (1)
- The following results were obtained in an experiment to determine the heat of neutralization of 50cm3 2M hydrochloric acid and 50cm3 2M sodium hydroxide.
Mass of...(Solved)
The following results were obtained in an experiment to determine the heat of neutralization of 50cm3 2M hydrochloric acid and 50cm3 2M sodium hydroxide.
Mass of plastic cup = 45.1g
Initial temperature of acid = 27.00C
Initial temperature of alkali = 23.00C
Mass of plastic cup + HCl + NaOH = 145.1g
Temperature of the mixture of acid and alkali = 38.50C
(a) Define heat of neutralization
(b) Write an ionic equation for the neutralization of hydrochloric acid and sodium hydroxide.
(i) The amount of heat produced during the experiment
(Specific heat capacity of solution = 4.2jg-1k-1, density of solution = 1gcm3)
(ii) Molar heat of neutralization for the reaction.
(c) Explain why the molar heat of neutralization of NaOH and Ethanoic acid of equal volume and molarity would be less than the value obtained in C (ii) above.
(d) Write down the thermochemical equation for reaction between NaOH and dilute hydrochloric acid
above
(e) Draw an energy level diagram for the neutralization reaction in (d) above.
Date posted: September 4, 2019. Answers (1)
- The apparatus below shows the set up that was used in the electrolysis of 2M Sulphuric (VI) acid.
Study it and answer the questions that follow.(Solved)
The apparatus below shows the set up that was used in the electrolysis of 2M Sulphuric (VI) acid.
Study it and answer the questions that follow.
(i) Write an equation for the reaction that produce gas F.
(ii) Describe how gas G can be identified
(iii) Why is the concentration of the acid expected to increase during electrolysis.
Date posted: September 4, 2019. Answers (1)
- Study the standard electrode potentials below and answer the questions that follow. The letters do not represent the actual symbols of the elements.(Solved)
Study the standard electrode potentials below and answer the questions that follow. The letters do not represent the actual symbols of the elements.
(i) Identify the strongest reducing agent. Give a reason.
(ii) Select two half cells when combined produce the highest potential difference and determine the electromotive force.
(iii) Which element is likely to be hydrogen? Give a reason
(iv) Explain whether the reaction represented below can take place.
Date posted: September 4, 2019. Answers (1)
- The chart shows the extraction of lead from its ore.(Solved)
The chart shows the extraction of lead from its ore.
(a) Write the chemical formula of the chief ore.
(b) Name the possible impurities present in the ore.
(c) Why is it necessary for the ore to be converted into powder form?
(d) Identify process X and state it‟s significance
(e) Write equations for the reaction taking place in the
I. Roasting furnace
II. Formation of substance B
It is not advisable to use lead pipes in transporting drinking water.
Explain why.
(f) Identify one of the impurities present in molten lead obtained by the process.
(g) State one use of lead
Date posted: September 4, 2019. Answers (1)
- The flow chart shows some chemical reactions.(Solved)
The flow chart shows some chemical reactions.
(a) Draw the structural formula and names of the following compounds.
(b) Write the name of the processes that leads to the formation of substances A and F.
(c) Name the type of reaction and conditions required for the formation Step 1
(d) If the relative molecular mass of compound X is 84000 units, determine the value of n (C = 12, H = 1)
(e) Write an equation that leads to the formation of substance E.
(f) State and explain the observation made when substances F and CH2=CH2 are burnt in excess air.
Date posted: September 3, 2019. Answers (1)
- A form one student crushed banana leaves with water and left the mixture for some days. He found that the mixture had fermented. He suspected...(Solved)
A form one student crushed banana leaves with water and left the mixture for some days. He found that the mixture had fermented. He suspected that the mixture had been contaminated with ethanol which has a boiling point of 780C while water has a boiling point of 1000C. The student then set up the apparatus below to separate the mixture.
(i) Name the piece of apparatus labelled B.
(ii) What is the purpose of the thermometer in the set up?
(iii) At what point of apparatus B should the tap water be connected. Explain.
(iv) Name the part labelled A and state its function
(v) Which liquid was collected first? Explain
(vi) What is the name given to the above method of separating mixtures?
(vii) What property of the components of the mixture makes it possible for the components to be separated by the method?
(viii) State two applications of the above method of separation.
(b) A form two student was supplied with a liquid suspected to be water.
(i) Describe one chemical test that would be carried out to show that the liquid was water.
(ii) How would it have been proved that the liquid is pure water?
Date posted: September 3, 2019. Answers (1)
- The grid below is part of the periodic table. Letters are not actual symbols. Study it and answer the
questions that follow.(Solved)
The grid below is part of the periodic table. Letters are not actual symbols. Study it and answer the
questions that follow.
(i) Give the letters representing atoms that can form a singly-charged anion.
(ii) Identify the most electromagnetic element in the grid. Explain.
(iii) Identify the strongest reducing agent.
(iv) Write the formula of the most stable compound formed when J and K react
(v) Give the name of the type of bond in the compound formed in (iv) above.
(vi) Give the chemical family name of L and M.
(vii) Write the ionic equation for the reaction in which gas L is bubbled through a solution with ions of M.
(viii) Element P is alkaline earth metal and belongs to period 2. Indicate its position on the grid.
Date posted: September 3, 2019. Answers (1)
- Production of hydrogen iodide can be demonstrated by the equation below(Solved)
Production of hydrogen iodide can be demonstrated by the equation below
Explain how the following would affect the yield of hydrogen iodide.
(i) Increase in temperature
(ii) Decrease in pressure
Date posted: September 3, 2019. Answers (1)