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(a) Gases can be identified by carrying out particular tests.
Some gases and tests to identify them are shown below.
Match the gases on the left with the tests on the right.
The first one has been done for you.
[4]
(b) Chlorine can be prepared by heating hydrochloric acid with manganese(IV) oxide.
$$ \text{MnO}_2 + 4\text{HCl} \rightarrow \text{MnCl}_2 + \text{Cl}_2 + 2\text{H}_2\text{O} $$
(i) Write a word equation for this reaction.
[3]
(ii) Chlorine is
• denser than air
• soluble in water.
Which one of the following diagrams, A, B or C, best describes how chlorine gas is collected?
Answer = ......................... [1]
(c) Hydrogen reacts with oxygen to form water.
(i) Complete the equation for this reaction.
$$ \text{2H}_2 + \ldots\ldots\ldots \rightarrow \ldots\ldots\ldots \text{H}_2\text{O} $$
[2]
(ii) State one use of
hydrogen, ...........................................................
................................................................................
water. ................................................................
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[2]
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(a) Which one of the following is alkaline?
Put a ring around the correct answer.
distilled water hydrochloric acid sodium chloride solution sodium hydroxide solution [1]
(b) Suggest a pH value for a solution which is alkaline.
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(c) Describe how you would find the pH of a solution.
.................................................................................................................................................. .................................................................................................................................................. .................................................................................................................................................. [2]
(d) When excess fertilisers are put on the soil, the soil may become acidic.
(i) Why is it important to farmers that the soil does not become too acidic?
................................................................................................................................. [1]
(ii) Calcium carbonate is used to decrease the acidity of the soil. Explain how calcium carbonate decreases soil acidity.
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The table below shows some properties of the halogens.
[Table_1]
| halogen | melting point/°C | boiling point/°C | colour |
|---|---|---|---|
| chlorine | −101 | −35 | |
| bromine | −7 | +59 | |
| iodine | +114 | +184 | greyish-black |
(a) (i) Complete the spaces in the table to show the colours of chlorine and bromine. [2]
(ii) Room temperature is about 20°C. Use the information in the table to explain why
chlorine is a gas at room temperature, .................................................................
........................................................................................................................
bromine is a liquid at room temperature. ..........................................................
........................................................................................................................ [2]
(iii) Astatine is the halogen below iodine in the Periodic Table. Suggest a value for the melting point of astatine.
........................................................................................................................ [1]
(b) Chlorine reacts with an aqueous solution of potassium iodide.
(i) Complete the balanced equation for this reaction.
$$Cl_2 + ..... KI \rightarrow 2KCl + .......$$ [2]
(ii) State the names of the products of this reaction.
........................................................................................................................ [2]
(iii) To which period in the Periodic Table does chlorine belong?
........................................................................................................................ [1]
(c) Complete the following sentences about the test for iodide ions using words from the list below.
hydrochloric nitric potassium precipitate
silver solution white yellow
A small volume of solution containing aqueous iodide ions is put into a test-tube. Dilute ........................ acid is added followed by a few drops of ...................... nitrate solution. A ........................ coloured ...................... is formed if iodide ions are present. [4]
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The diagram below shows the structure of some substances containing nitrogen.
(a) (i) Which one of these substances, A, B, C, D or E, is an alkaline gas?
(ii) Which one of these substances is an ionic salt?
(iii) Which one of these substances contains a carboxylic acid functional group?
(b) Oxides of nitrogen such as nitrogen dioxide, $\text{NO}_2$, are atmospheric pollutants. Give one source of nitrogen oxides in the air.
(c) State one harmful effect of nitrogen dioxide.
(d) Calculate the relative formula mass of nitrogen dioxide, $\text{NO}_2$.
(e) In the presence of a catalyst, nitrogen dioxide reacts with carbon monoxide.
$2\text{NO}_2 + 4\text{CO} \rightarrow \text{N}_2 + 4\text{CO}_2$
(i) Which substance gets oxidised during this reaction? Explain your answer.
(ii) What is the meaning of the term catalyst?
(iii) Carbon monoxide is formed when some of the air holes in a water heater get blocked. The diagram shows a water heater.
Explain why carbon monoxide is formed when some of the air holes in a water heater get blocked.
(iv) Explain why carbon monoxide is dangerous.
554
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(a) State three other physical properties of a transition element.
.................................................................................................................................
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(b) Iron reacts with sulfuric acid.
Fe + H_2SO_4 \rightarrow FeSO_4 + H_2
(i) Write a word equation for this reaction.
.................................................................................................................................
[2]
(ii) Describe, with the aid of a diagram, how you could measure the speed of this reaction. In your answer describe:
• the apparatus you would use
• the measurements you would take.
.................................................................................................................................
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[4]
(c) When iron reacts with sulfur, energy is released.
(i) What is the name given to a reaction which releases energy?
.................................................................................................................................
[1]
(ii) The compound formed in this reaction is iron(II) sulfide. What do you understand by the term compound?
.................................................................................................................................
[1]
(iii) The diagram below shows the structure of iron(II) sulfide.
What is the simplest formula for iron(II) sulfide?
.................................................................................................................................
[1]
556
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520
The diagram shows a fractionating column used to separate different hydrocarbon fractions in an oil refinery.
(a) On the diagram, draw an X to show the place in the column where the temperature is the highest. [1]
(b) State the name of the fraction labelled A. [1]
(c) State a use for
the kerosene fraction, ........................................................
the diesel oil fraction. ......................................................... [2]
(d) Complete the following sentences about fractional distillation using words from the list below.
boiling condenses cooled heated higher lower melting mixture pressure vaporises
Petroleum is a .................................. of hydrocarbons. This mixture is .................................. and the hydrocarbons vaporise. The temperature in the fractionating column is ................................. at the top than at the bottom. As the vapours move up the column, each hydrocarbon fraction ................................. when the temperature in the column falls below the ................................. point of the hydrocarbon fraction. [5]
(e) The structures of four hydrocarbons, A, B, C and D, are shown below.
(i) Which two of these structures A, B, C or D have the same relative molecular mass? ...................................................... and ...................................................... [1]
(ii) Which two of these structures A, B, C or D will decolourise aqueous bromine? ...................................................... and ...................................................... [2]
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A student placed some crystals of salt at the bottom of a beaker of distilled water. She left the contents of the beaker to stand for one hour. The diagram below shows her observations.
After one hour, all the salt had disappeared but the solution at point X tasted salty.
(a) Use the kinetic particle theory to explain these observations.
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(b) Salt is sodium chloride, NaCl.
(i) Which one of the following statements about bond formation in sodium chloride is true?
Tick one box.
A sodium atom shares one electron with a chlorine atom. [ ]
A sodium atom loses its outermost electron and a chlorine atom gains an electron. [ ]
A sodium atom shares two electrons with a chlorine atom. [ ]
A sodium atom gains an electron and a chlorine atom loses its outermost electrons. [ ] [1]
(ii) Explain why solid sodium chloride does not conduct electricity but molten sodium chloride does conduct.
....................................................................................................................................
....................................................................................................................................
.................................................................................................................................... [2]
(iii) State the name of the product formed at each electrode when a concentrated aqueous solution of sodium chloride is electrolysed using graphite electrodes.
at the positive electrode .......................................................... [2]
at the negative electrode .......................................................... [2]
(iv) What is the name of the negative electrode?
Put a ring around the correct answer.
anion anode cation cathode electrolyte [1]
(v) Suggest why graphite is a suitable material for an electrode.
.................................................................................................................................... [1]
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