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Study the flow chart in Figure 5 and answer the questions that follow.
(a) Identify substances K and L. K:
(b) Name one reagent that can be used to carry out process J.
ANSWERS
The following procedure was used to investigate the temperature changes that occur when sodium hydroxide solution is added to dilute hydrochloric acid.
(i) Place the acid in a glass beaker and record its temperature. (ii) Add a known volume of sodium hydroxide solution. (iii) Stir the mixture and record the highest temperature reached. (iv) Repeat steps (ii) and (iii) with different volumes of sodium hydroxide solution. (a) State two factors that must be kept constant in this experiment (b) Explain how the use of a polystyrene cup will affect the results.
ANSWERS
The set-up in Figure 4 can be used to prepare nitrogen (II) oxide. Use it to answer the questions that follow.
(a) Name substance A
(b) When the gas jar containing nitrogen (II) oxide is exposed to air, a brown color is observed. Explain. (c) Write an equation for the reaction which occurred in the flask.
ANSWERS
The flow chart in Figure 3 shows the process of obtaining a sample of nitrogen gas. Study it and answer the questions that follow.
(a) Identify X
(b) Write an equation for the reaction with heated copper turnings. (c) Name an impurity in the sample of nitrogen gas.
ANSWERS
In an experiment, concentrated nitric(V) acid was reacted with iron(II) sulphate. State and explain the observations made.
ANSWERS
The mixture changed from green to yellow / formation of a brown gas;
Iron(II) ions is oxidized by nitric(V) acid to Iron(III) ions / nitric(V) acid is reduced to nitrogen(1I) oxide which is oxidized by oxygen to nitrogen(IV ) oxide.
Starting with copper, describe how a pure sample of copper(II) carbonate can be prepared.
ANSWERS
Using the elements chlorine, calcium and phosphorus:
(a) Select elements that will form an oxide whose aqueous solution has a pH less than 7. (b) Write an equation for the reaction between calcium oxide and dilute hydrochloric acid. (c) Give one use of calcium oxide.
ANSWERS
Explain the observation made when chlorine gas is passed through a solution of potassium iodide.
ANSWERS
Potassium nitrate liberates oxygen gas when heated. Draw a diagram of a set-up that shows heating of potassium nitrate and collection of oxygen gas.
ANSWERS
An oxide of element K has the formula K2O5.
(a) Determine the oxidation number of K. (b) To which group of the periodic table does K belong?
ANSWERS
20 cm3 of ethanoic acid was diluted to 400 cm3 of solution. Calculate the concentration of the solution in moles per litre. (C = 12.0 ; H = 1.0 ; 0 =16.0) (Density of ethanoic acid = 1.05 g/cm3)
ANSWERS
Copper(II) ions react with excess aqueous ammonia to form a complex ion.
(a) (i) Write an equation for the reaction that forms the complex ion. (ii) Name the complex ion. (b) Explain why CH4 is not acidic while HCl is acidic yet both compounds contain hydrogen.
ANSWERS
(a) State one characteristic of a reaction where equilibrium has been attained.
ANSWERS
A sample of water is suspected to contain sulphate ions. Describe an experiment that can be carried out to determine the presence of sulphate ions.
ANSWERS
(a) State Charles' Law.
(b) Explain why the pressure of a fixed mass of a gas increases, when the volume of the gas is reduced at constant temperature.
ANSWERS
(a)The volume of a fixed mass of a gas is directly proportional to the absolute temperature at constant pressure.
(b)As the volume decreases, there is increased bombardment / collisions of the molecules against the walls of the container, hence increased pressure. |
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December 2024
AuthorMaurice Atika is a teacher and a netprenuer. |
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