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Form 3 Nitrogen and Its Compounds Questions and Answers
Explain why a high temperature is required for nitrogen to react with oxygen.
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1.
The table below gives some properties of gases D and E. (a) Describe how you would obtain a sample of E from a mixture of gases D and E. (b) Suggest a possible identity of gas D. Give a reason for your answer.
2.
Dilute nitric (V) acid reacts with copper according to the equation; #3CU_((s)# +# 8H^+(aq)# + #2NO_3(aq)# #rightarrow# #3Cu^(+2)(aq)# + 2NO(g) + #4H_2 O(l)# (a) What is the oxidation number of nitrogen in (i) #NO_3^-# (ii) NO (b) With respect to nitrogen, explain whether the above reaction is an oxidation or reduction process.
3.
(a) The diagram below shows a set-up that can be used to obtain nitrogen gas in an experiment. (i) Name liquid L. (ii) What observation would be made in tube K after heating for some time? (iii) Write an equation for the reaction that took place in tube K. (iv) If 320 #cm^3# of ammonia gas reacted completely with the copper, calculate:n (I) Volume of nitrogen gas provided. (II) The mass of copper
4.
(a) The diagram below represents a set up that was used to obtain dry nitrogen from air. Study it and answer the questions that follow: (i) Name solid Q. (ii) What is the purpose of sodium hydroxide? (iii) Write an equation for the reaction which took place in tube P. (iv) Give the name of one impurity present in the nitrogen gas obtained. (v) Give a reason why liquid nitrogen is used for storage
5.
The flow chart below shows the industrial preparation of ammonia and the process used in the manufacture of some ammonium compounds. Study it and answer the questions that follow. (a) Give the name of the: (i) Process in step 1 (ii) Reaction that takes place in step 5. (b) State one other source of hydrogen gas apart from natural gas. (c) Explain why it is necessary to compress nitrogen and
6.
(a) A few drops of freshly prepared iron (II) sulphate solution were added to potassium nitrate solution in a test-tube. Concentrated sulphuric (VI) acid was then carefully added to the mixture. State the observations that were made. (b) Write an equation for the reaction that occurs when solid potassium nitrate is strongly heated.
7.
A student set up the apparatus shown below to prepare ammonia gas and react it with copper (II) sulphate solution. (a) Identify solution V. (b) State the observations which were made in the beaker.
8.
Study the scheme below and answer the questions that follow. (a) Identify solid E. (b) Write an ionic equation for the reaction in step II that produces solid F.
9.
(a) Fractional distillation of liquid air usually produces nitrogen and oxygen as the major products. (i) Name one substance that is used to remove carbon (IV) oxide from the air before it is changed into liquid. (ii) Describe how nitrogen gas is obtained from the liquid air. (Boiling points nitrogen= -1960 C, oxygen= -1830 C). (b) Study the flow chart below and answer the following questions.
10.
Concentrated nitric (V) acid was added to Iron (II) sulpahte acidified with dilute sulphuric (VI) acid and the mixture heated. The solution turned from pale green to yellow with evolution of brown gas. Explain these observations.
11.
(a) Give a reason why concentrated sulphuric (VI) acid is not used to dry ammonia gas. (b) Name one suitable drying agent for ammonia gas.
12.
Nitrogen (II) oxide and nitrogen (IV) oxide are some of the gases released from car exhaust pipes. State how these gases affect the environment.
13.
Ammonium nitrate was gently heated and the products collected as shown in the diagram below. Describe one chemical and one physical method that can be used to identify gas G.
14.
In the Haber process, the optimum yield of ammonia is obtained when a temperature of 4500 C, a pressure of 200 atmospheres and an iron catalyst are used. (a) How would the yield of ammonia be affected if the temperature was raised to 6000 C? (b) Give one use ammonia.
15.
Ammonia gas was passed into water as shown below. (a) Explain why the pH of solution is above 7. (b) What is the use of inverted tunnel?
16.
Ammonium nitrate was heated as shown in the set-up below. (a) Identify gas A. (b) State and explain a precaution that must be taken before heating is stopped.
17.
Nitrogen forms many compounds in which its oxidation state varies. (a) What is meant by oxidation state? (b) What is the oxidation state of nitrogen in# Mg_3 N_2#.
18.
Explain why a high temperature is required for nitrogen to react with oxygen.
19.
(a) The flow chart below shows some reactions starting with lead (II) nitrate. Study it and answer the questions that follow. (i) State the condition necessary in step 1. (ii) Identify: (I) Reagent K. (II) Gas Q. (III) Acidic products S and R. (iii) Write: (I) The formula of the complex ion formed in step 3. (II) The equation of the reaction in step 4. (b) The use of materials made of lead in roof
20.
State one use of sodium hydrogen carbonate.
21.
The diagram below shows a set-up that was used to prepare and collect a sample of nitric (V) acid. (i) Give a reason why it is possible to separate nitric (V) acid from sulphuric (VI) acid in the set-up. (ii) Name another substance that can be used instead of potassium nitrate. (iii) Give one use of nitric (V) acid.
22.
When a few drops of aqueous ammonia were added to copper (II) nitrate solution, a light blue precipitate was formed. On addition of more aqueous ammonia, a deep blue solution was formed. Identify the substance responsible for the: (i) Light blue precipitate. (ii) Deep blue solution.
23.
(a) Name one raw material from which sodium hydroxide is manufactured. (b) Sodium hydroxide pellets were accidentally mixed with sodium chloride. 17.6g of the mixture were dissolved in water to make one litre of solution. 100#cm^3# of the solution was neutralized by 40#cm^3# of 1.5M sulphuric (VI) acid. (i) Write an equation for the reaction that took place. (ii) Calculate the: (I) Number of moles
24.
The first step in the industrial manufacture of nitric (V) acid is the catalyst oxidation of ammonia gas. (a) What is the name of the catalyst used? (b) Write the equation for the catalyst oxidation of ammonia gas. (c) Nitric (V) acid is used to make ammonium nitrate, state two uses of ammonium nitrate.
25.
In an experiment, a few drops of concentrated nitric (V) acid were added to aqueous iron (II) sulphate in a test-tube. Excess sodium hydroxide solution was then added to the mixture. (a) State the observations that were made when: (i) Concentrated nitric (V) acid was added to aqueous iron(II) sulphate. (ii) Excess sodium hydroxide was added to the mixture. (b) Write an ionic equation for the react
26.
When magnesium was burnt in air, a solid mixture was formed. On addition of water to the mixture, a gas which turned moist red litmus paper blue was evolved. Explain these observations.
27.
(a) Describe the process by which nitrogen is obtained from air on a large scale. (b) Study the flow chart below and answer the questions that follow. (i) Identify gas J. (ii) Using oxidation numbers, show that ammonia is the reducing agent in step (VI). iii) Write an equation for the reaction that occurs in step(V) iv) Give one use of ammonium nitrate. c)The table below shows the observations mad
28.
(a) The schematic diagram below shows part of the Solvay process used for the manufacture of sodium carbonate. (i) Explain how the sodium chloride required for this process is obtained from sea water. (ii) Two main reactions take place in UNIT I The first one is the formation of ammonium hydrogen carbonate. (I) Write an equation for this reaction (II) Write an equation for the second reaction.
29.
In an experiment to prepare nitrogen (I) oxide, ammonium nitrate was gently heated in a flask. (a) Write the equation for the reaction that took place in the flask. (b) State and explain how the gas was collected. (c) A sample of the gas was tested with damp blue and red litmus papers. What observations were made?
30.
The set-up below shows how nitrogen gas is prepared in the laboratory. (a) Describe how nitrogen gas is formed in the flask. (b) Nitrogen is inert. State one use of the gas based on this property.
31.
Study the flow chart below and answer the questions that follow. (a) Name the suitable drying agent for ammonia (b) Describe one chemical test for ammonia (c) Name x
32.
In the laboratory small quantities of nitric (V) acid can be generated using the following set up. Study it and answer the questions that follow (a) (i)Give the name of substance R (ii)Name one other substance that can be used in place of sodium nitrate (iii)What is the purpose of using tap water in the setup above (b)Explain the following (i)Its not advisable to use a stopper made of rubber in
33.
The scheme below shows some reaction sequence starting with solid N. Study it and answer the questions that follow. Write the formula of the complex ion in solution Q. Write an equation for the reaction in step IV.
34.
When fuels are burn in the internal combustion engine at high temperature one of the products formed is nitrogen (II) oxide. (a) Write the equation for the formation of nitrogen (ii) oxide. (b) Give a reason why nitrogen (II) oxide is not formed at room temperature . (c) Describe how formation of nitrogen (II) oxide in the internal combustion engine leads to gaseous pollution.
35.
On heating a pale green solid K, carbon (IV) oxide gas and a black solid m were formed. On reacting K with dilute hydrochloric acid, carbon (IV) oxide gas and a green solution s were formed. When excess aqueous ammonia was added to solution s , a deep blue solution was formed. (a) Identify the cation in solid k (b) Identify the two anions in solution S
36.
Study the flow chart below and answer the questions that follow; (i) Write an equation for the reaction in: Step II Step IV (ii) State the observation made in step III. Explain. (iii) Name another substance that can be used in step V
37.
Dry ammonia gas was passed over heated lead (II) oxide and the products passed over anhydrous copper (II) sulphate as shown in the diagram below (i) State two observations made in the combustion tube (ii) The property of ammonia gas in this experiment
38.
Study the setup below and answer the questions that follow (a) Write an equation for the reaction between ammonia and copper (II) oxide (b) During the experiment the colour of the contents in the water trough changed. State the colour change observed and give an explanation
39.
A student used the setup below to prepare a sample of nitrogen gas (a) State the function of potassium hydroxide in the setup (b) Give a suitable metal M for use in the combustion tube (c) Give a reason why the nitrogen gas obtained is not pure
40.
Dry ammonia and dry oxygen were reacted were reacted as shown in the diagram below. (a) What is the purpose of the glass wool. (b) What products would be formed if red hot platinum was introduced into a mixture of ammonia and oxygen.
41.
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 CH
4
is not acidic while HCl is acidic yet both compounds contain hydrogen.
42.
In an experiment, concentrated nitric(V) acid was reacted with iron(II) sulphate. State and explain the observations made.
43.
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 colour is observed. Explain. (c) Write an equation for the reaction which occurred in the flask.
44.
In the Haber process, nitrogen reacts with hydrogen according to the following equation. 3H
2
(g) + N
2
(g) 2NH
3
(g) ; AH = —#92 kJ mol^(-1)# (a) What would be the effect of adding a catalyst on the position of the equilibrium? (b) Explain why it is not advisable to use temperatures higher than 773 K in the Haber process.
45.
When burning magnesium ribbon is introduced into a gas jar full of nitrogen, it continues to burn producing a greenish yellow powder. (a) Write an equation for the reaction between nitrogen and magnesium. (b) Explain why magnesium continues to bum in nitrogen but sulphur does not. (c) State one use of nitrogen.
46.
Figure 3 is a flow chart that shows the process that occurs in the manufacture of nitric(v) acid, it produces a nitrogenous fertilizer (a) Name substance P, Q, R and S. P (b) To obtain substance R, ammonia is heated at 900°C in the presence of air and a catalyst.The product is then cooled in air. (i) Name the catalyst for the reaction. (ii) Write the equations for the two reactions described in
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