KCSE CHEMISTRY QUESTIONS AND ANSWERS PER TOPIC
When 94.5g of hydrated barium hydroxide, ba(OH)2. nH2O were heated to constant mass, 51.3g of anhydrous barium hydroxide were obtained. Determine the empirical formula of the hydrated barium hydroxide.
0 Comments
A group of compounds called chlorofluorocarbons have a wide range of uses but they also have harmful effects on the environment.
State one: a) Use of chlorofluorocarbons b) Harmful effect of chlorofluorocarbons on the environments.
ANSWERS
a)Refrigeration
b) - They deplete the ozone layer. - They cause green house effect.
In an experiment to study the properties of concentrated sulphuric acid, a mixture of the acid and wood charcoal was heated in a boiling tube.
(a) write the equation of the reaction that took place in the boiling tube. (b) Using oxidation numbers, show that reduction and oxidation reactions took place in the boiling tube
60cm3 of oxygen gas diffused through a porous partition in 50 seconds. How long would it take 60cm3 of sulphur (IV) oxide gas to diffuse through the same partition under the same conditions? (S= 32.0, 0 = 16.0)
(a) In an experiment, dry hydrogen chloride gas was passed through heated zinc turnings as shown in the diagram below. The gas produced was then passed through heated lead (II) oxide.
Calculate the mass of nitrogen dioxide gas that would occupy the same volume as 10g of hydrogen gas at same temperature and pressure.(H = 1.0, N = 14.0, o = 16.0)
Name and draw the structure of the compound formed when methane reacts with excess chlorine in the presence of U.V light.
When dilute nitric acid was added to a sample of solid C, a colourless gas that formed a white a white precipitate with lime water was produced. When another sample of solid C was heated strongly in a dry test – tube, there was no observable change.
(a) What is meant by isomerism?
(b) Draw and name two isomers of butane.
(a) Name one raw material which sodium hydroxide is manufactured
(b) Sodium hydroxide pellets were accidentally mixed with sodium chloride 17.6 g of the mixture were dissolved in water to make one litre of solution. 100 cm3 of the mixture were dissolved in water to make one litre solution. 100cm3 of the solution was neutralized by 40cm3 of 0.M sulphuric acid (i) Write an equation for the reaction that took place (ii) Calculate the: (i) Number of moles of the substance that reacted with sulphuric acid (ii) Number of moles of the substances that would react with sulphuric acid in the one litre of solution (iii) Mass of the unreacted substances in one litre of solution (H = 1,0 ; Na = 23.0 ; Cl= 35.5 ; 0= 16.0) (c) The diagram below shows an incomplete set-up used to prepare and collect ammonia gas
(i) Name solid M
(ii) Complete the diagram to show how a dry sample of ammonia gas can be collected (d) In an experiment, excess ammonia gas passed over heated copper (II) oxide on a combustion tube. (i) State the observation that was made in the combustion tube at the end of the experiment (ii) What property of ammonia is shown in the above reaction (iii) Name one use of ammonia
When a hydrocarbon was completely burnt in oxygen, 4.2g of carbon dioxide and 1.71 g of water were formed. Determine the empirical formula of the hydrocarbon
(H= 1.0 ; C=12.0 ; 0 = 16.0)
When a few drops of aqueous ammonia were added to copper (II) nitrate solution, a light tube precipitate was formed. On addition of more aqueous ammonia, a deep blue solution was formed.
Identify the substance responsible for the: a. Light blue precipitate b. Deep blue solution
ANSWERS
In an experiment, a gas jar containing most sulphur dioxide was inverted over another gas jar containing hydrogen sulphide gas
a. State and explain the observation that was made b. State the precaution that should be taken when carrying out this experiment
ANSWERS
ANSWERS
ANSWERS
(a) The graph below shows the solubility of sulphur dioxide gas at different temperatures. Use the following in it to answer the questions that follow.
(i) From the graph determine: I The lowest temperature at which 1,000cm3 of solution would contain 116g of sulphur dioxide. II The maximum mass of sulphur dioxide that would dissolve in 15 litres of solution at 100C (ii) Sodium hydroxide reacts with sulphur trioxide according to the following equation. Using the information in the graph determine the volume of 2M sodium hydroxide required to completely neutralize on one litre of saturated sulphur dioxide solution 230C. (S=32.0; O; O = 16.0) (3mks) (b) Study the flow chart below and answer the questions that follow. Write equation for the reaction taking place at: I The roasting furnace (1mk) II The absorption tower (1mk) III The diluter (1mk) (ii) The reaction taking place in chamber K is I Explain why it is necessary to use excess air in chamber K II Name another substance used in chamber K (c) Study the scheme given below and answer the questions that follow: (i) Name the reagents used in: Step I……………… (1mk) Step II……………… (1mk) Step IV…………… (1mk) (ii) Write an equation for the complete combustion of CH = CH (1mk) Explain one disadvantage of the continued use of items made from the compound formed in step III (2mks)
The reaction between how concentrated sodium hydroxide and chlorine produces sodium chlorate (V), sodium chloride and water
(a) Write the equation for the reaction (b) Give one use of sodium chlorate (V)
A certain carbonate, GCO3, reacts with dilute hydrochloric acid according to the equation given below:
GCO3(s) + 2HCL(aq)= GCl2 (aq) + (CO2(g) + H2O(l) If 1 g of the carbonate reacts completely with 20 cm3 of 1 M hydrochloric acid ,calculate the relative atomic mass of G (C = 12.0 = 16.0)
Determine the oxidation state of sulphur in the following compounds:
a) H2S……………………… b) Na2S……………………
Give the name and draw the structural formula of the compound formed when one mole of ethane reacts with one mole of chlorine gas.
Calcium oxide can be used to dry ammonia gas.
a) Explain why calcium oxide is not used to dry hydrogen chloride gas b) Name one drying agent for hydrogen chloride gas
State one use of sodium hydrogen carbonate.
ANSWERS
|
Chemistry Topics
All
Archives
December 2024
|
We Would Love to Have You Visit Soon! |
Hours24 HR Service
|
Telephone0728 450425
|
|
8-4-4 materialsLevels
Subjects
|
cbc materialsE.C.D.E
Lower Primary
Upper Primary
Lower Secondary
Upper Secondary
|
teacher support
Other Blogs
|