- Two experiments were carried out as follows and the volume of hydrogen gas evolved measured at intervals of 10 seconds for 100 seconds.(Solved)
Two experiments were carried out as follows and the volume of hydrogen gas evolved measured at intervals of 10 seconds for 100 seconds.
i) 8cm of magnesium ribbon was added to 1M HCl(aq)
(ii) 8cm of magnesium ribbon was added to 0.5M HCl(aq)
Graphs of volume of hydrogen gas evolved against time were plotted as shown below.
a) Which of the graphs was obtained for reaction (i). Explain.
(b) Explain the general shape of the graphs.
Date posted: March 29, 2019. Answers (1)
- An organic compound with the formula C4H10O reacts with potassium metal to give hydrogen gas and a white solid.(Solved)
An organic compound with the formula C4H10O reacts with potassium metal to give hydrogen gas and a white solid.
(a) Write structural formula of the compound.
(b) To which homologous series does the compound belong?
(c) Write the equation for the reaction between the compound and potassium metal.
Date posted: March 29, 2019. Answers (1)
- Give the systematic names of the following compound: CHCH=CHCH2CH3.(Solved)
Give the systematic names of the following compound: CHCH=CHCH2CH3.
Date posted: March 29, 2019. Answers (1)
- A known volume of ozone diffuses through a small hole in 55 seconds; whereas the same amount of chlorine takes 67 seconds under the same...(Solved)
A known volume of ozone diffuses through a small hole in 55 seconds; whereas the same amount of chlorine takes 67 seconds under the same conditions.Determine the molecular mass of ozone . (Cl=35.5; O=16)
Date posted: March 29, 2019. Answers (1)
- Sulphur (IV) oxide gas was bubbled into acidified potassium chromate (VI) and iron (III) sulphate solutions respectively.Explain the observations made in each case.(Solved)
Sulphur (IV) oxide gas was bubbled into acidified potassium chromate (VI) and iron (III) sulphate solutions respectively.Explain the observations made in each case.
i) With potassium chromate (VI).
(ii) With iron (III) sulphate.
Date posted: March 29, 2019. Answers (1)
- An oxide of carbon contains 42.8% by mass of carbon and has R.M.M. of 28. What is its molecular formula?
(C=12;O=16)(Solved)
An oxide of carbon contains 42.8% by mass of carbon and has R.M.M. of 28. What is its molecular formula?
(C=12;O=16)
Date posted: March 29, 2019. Answers (1)
- 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)