Get premium membership and access questions with answers, video lessons as well as revision papers.
- Below are the bond dissociation energies of some elements.(Solved)
Below are the bond dissociation energies of some elements.
Calculate the enthalpy change of the reaction.
Date posted: March 29, 2019. Answers (1)
- The solubility of salt Y at 600 is 40g/100g of water and 48g/100g of water at 1000C.
(i) How much salt Y would saturate 190g of...(Solved)
The solubility of salt Y at 600 is 40g/100g of water and 48g/100g of water at 1000C.
(i) How much salt Y would saturate 190g of water at 1000C.
(ii) 150g of saturated solution of Y at 1000C is cooled to 600C. Calculate the mass of Y that crystallizes out.
Date posted: March 29, 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) Explain why the ionic radius of K+ is greater than that of Na+
(b) Account for the difference in ionic radius of Mg2+ and Na+
Date posted: March 29, 2019. Answers (1)
- Four solutions of pH 7, 2, 8.5 and 13 respectively were each reacted with calcium turnings. Identify two solutions in which hydrogen gas would be...(Solved)
Four solutions of pH 7, 2, 8.5 and 13 respectively were each reacted with calcium turnings. Identify two solutions in which hydrogen gas would be produced. Explain each case.
Date posted: March 29, 2019. Answers (1)
- Describe how you would prepare a dry sample of zinc carbonate in the laboratory starting with zinc chloride solid.(Solved)
Describe how you would prepare a dry sample of zinc carbonate in the laboratory starting with zinc chloride solid.
Date posted: March 29, 2019. Answers (1)
- Briefly explain an industrial application of the following processes.(Solved)
Briefly explain an industrial application of the following processes.
a) Crystallization.
(b) Fractional distillation.
Date posted: March 29, 2019. Answers (1)
- The diagrams below represent a list of apparatus which are commonly used in a chemistry laboratory:-(Solved)
The diagrams below represent a list of apparatus which are commonly used in a chemistry laboratory:-
(a) Give the correct order of the apparatus, using the letters only, show the correct arrangement that can be used to prepare and investigate the nature of PH of a sample of onion solution.
(b) Name one chemical substance and apparatus that is needed in the experiment.
Date posted: March 29, 2019. Answers (1)
- Use the information in the table below to determine the relative atomic mass of copper.(Solved)
Use the information in the table below to determine the relative atomic mass of copper.
Date posted: March 29, 2019. Answers (1)
- Draw structural formulae of two positional isomers with molecular formula C4H8.(Solved)
Draw structural formulae of two positional isomers with molecular formula C4H8.
Date posted: March 29, 2019. Answers (1)
- Use the equation below to answer the questions that follow.(Solved)
Use the equation below to answer the questions that follow.
Using oxidation numbers show where reduction has taken place.
Date posted: March 29, 2019. Answers (1)
- The curve shown below was obtained when solid naphthalene was heated to boiling.(Solved)
The curve shown below was obtained when solid naphthalene was heated to boiling.
(a) Explain in molecular terms the changes occurring in portions.
(i) AB.
(ii) DE.
(b) What is the significance of portion BC?
Date posted: March 29, 2019. Answers (1)
- 3.22g of hydrated sodium sulphate, Na2SO4.XH2O were heated to a constant mass of 1.42g. Determine the value of X in the formula. (Na = 23.0,...(Solved)
3.22g of hydrated sodium sulphate, Na2SO4.XH2O were heated to a constant mass of 1.42g. Determine the value of X in the formula. (Na = 23.0, S = 32.0, O = 16.0, H = 1).
Date posted: March 29, 2019. Answers (1)
- The figure below shows a set-up used in electrolysis of lead iodide.(Solved)
The figure below shows a set-up used in electrolysis of lead iodide.
(a) Why is heating necessary?
(b) Write the equation of the reaction that occurs at the cathode.
(c) At which electrode does reduction occurs.
Date posted: March 29, 2019. Answers (1)
- Solid J reacts with cold water but solid K does not. L reduces the oxide of M but does not reduce the oxide of K....(Solved)
Solid J reacts with cold water but solid K does not. L reduces the oxide of M but does not reduce the oxide of K. Arrange the elements in order of reactivity starting with the most reactive.
Date posted: March 29, 2019. Answers (1)
- In terms of structure and bonding explain why the component Cl2O has a very low melting and boiling point.(Solved)
In terms of structure and bonding explain why the component Cl2O has a very low melting and boiling point.
Date posted: March 29, 2019. Answers (1)
- Draw a dot (.)/cross (X) diagram to show bonding in Cl2O. (Cl = 17, O = 8).(Solved)
Draw a dot (.)/cross (X) diagram to show bonding in Cl2O. (Cl = 17, O = 8).
Date posted: March 29, 2019. Answers (1)
- The following chromatogram was obtained in an experiment to investigate the components present in certain dyes.(Solved)
The following chromatogram was obtained in an experiment to investigate the components present in certain dyes.
(a) Which two dyes when mixed would produce A?
(b) Which dye is pure?
(c) Indicate on the diagram the solvent front.
Date posted: March 29, 2019. Answers (1)
- 1.26g of lead powder were dissolved in excess nitric (VI) acid to form lead nitrate solution. All the lead nitrate solution was reacted with sodium...(Solved)
1.26g of lead powder were dissolved in excess nitric (VI) acid to form lead nitrate solution. All the lead nitrate solution was reacted with sodium sulphate solution.
(a) Write an ionic equation for the reaction between lead nitrate and sodium sulphate solutions.
(b) Determine the mass of lead salt formed in (a) above (Pb = 207, S = 32, O = 16).
Date posted: March 29, 2019. Answers (1)
- A dry cell is constructed using the following substances. Zinc metal, graphite rod, ammonium chloride paste and manganese (IV) oxide mixed with carbon powder.
(a) State...(Solved)
A dry cell is constructed using the following substances. Zinc metal, graphite rod, ammonium chloride paste and manganese (IV) oxide mixed with carbon powder.
(a) State the roles of:
(i) Ammonium chloride paste.
(ii) Manganese (IV) oxide mixed with carbon powder.
(b) Given that:
Calculate the e m f of the cell given zinc forms the negative electrode.
Date posted: March 29, 2019. Answers (1)
- Dry hydrogen chloride gas was passed over heated iron wool as shown below.(Solved)
Dry hydrogen chloride gas was passed over heated iron wool as shown below.
(a) State the observation made in the combustion tube at the end of the experiment.
(b) Write the equation for the reaction taking place:-
(i) In the combustion tube.
(ii) Leading to production of the blue flame.
Date posted: March 29, 2019. Answers (1)