Cambridge IGCSE Chemistry - 0620 - Core Paper 3 2010 Summer Zone 2

The diagram shows part of the Periodic Table. Only some of the elements are shown. (a) Answer the following questions by choosing only from the elements shown in the diagram. You can use each element once, more than once or not at all. (i) State the names of two transition elements shown in the diagram. ................................................ and ................................................ [2]
(ii) State the name of an element which is in Period 3 of the Periodic Table. .............................................................................................................................. [1]
(iii) Which element has the electronic structure 2,8,1? .............................................................................................................................. [1]
(iv) Which element has the fastest reaction with water? .............................................................................................................................. [1]
(v) Which element has 23 protons in its nucleus? .............................................................................................................................. [1] (b) Sodium reacts with oxygen to form sodium peroxide, $Na_2O_2$. Complete the symbol equation for this reaction. .............. Na + .............. → $Na_2O_2$ [2]

The list describes five types of chemical structures.
giant covalent
giant ionic
metallic
simple atomic
simple molecular

(a) The diagrams below show four types of chemical structures.

(i) Use the list to match these structures with the diagrams.
structure A is .......................................................... [1]
structure B is .......................................................... [1]
structure C is .......................................................... [1]
structure D is .......................................................... [1]
(ii) Which two of the structures A, B, C or D have low melting points?
........................ and ........................ [1]

(b) Sodium chloride is an ionic solid.
Complete the following sentences using words from the list.
electrons ionic molecular molten solid
Sodium chloride does not conduct electricity when it is a ........................ because the ions cannot move. When it is ........................ sodium chloride does conduct electricity because the ions are free to move. [2]

Water is an important raw material in industry.
(a) State one use of water in industry.
........................................................................................................................................................................................... [1]
(b) Describe a chemical test for water.
test .........................................................................................................................................................................................
result ....................................................................................................................................................................................... [2]
(c) A small piece of potassium was placed in a beaker of water. The equation for the reaction is
$$2K(s) + 2H_2O(l) \rightarrow 2KOH(aq) + H_2(g)$$
(i) Describe a test for the gas given off in this reaction.
test ........................................................................................................................................................................................
result ...................................................................................................................................................................................... [2]
(ii) What is the most likely pH of the solution in the beaker when the reaction is complete?
Put a ring around the correct answer.
pH2 pH6 pH7 pH8 pH12 [1]
(d) Water is formed when propane burns.
(i) Complete the equation for this reaction.
$$C_3H_8 + 5O_2 \rightarrow \text{..............}CO_2 + \text{..............}H_2O$$ [2]
(ii) Which of the following best describes this reaction?
Put a ring around the correct answer.
carbonisation combustion dehydration hydrogenation [1]
(iii) When 4.4 g of propane are burnt in excess oxygen, 7.2 g of water are formed.
Calculate the mass of water formed when 22 g of propane are burnt. [1]

A student half-filled a syringe with water.
She then carefully drew up some blue ink into the syringe so that it formed a separate layer below the water.
She then left the syringe in a clamp for twenty hours.
After twenty hours the blue colour of the ink had spread throughout the water.
(a) Use the kinetic particle theory to explain these observations.
................................................................................................................................................................
................................................................................................................................................................
................................................................................................................................................................ [2]
(b) Ink is a mixture of many chemicals.
What do you understand by the term \textit{mixture}?
................................................................................................................................................................
................................................................................................................................................................ [1]
(c) The list shows some of the substances present in ink.
\begin{align*}\text{carboxylic acids}\ & \text{cobalt(II) ions}\ & \text{ethanol}\ & \text{iron(II) ions}\ & \text{nickel(II) ions}\ & \text{tannins}\ & \text{water}\end{align*}
(i) Water is a good solvent.
From the list choose one other substance that is a good solvent.
................................................................................................................................................................ [1]
(ii) What is the meaning of the symbol (II) in iron(II)?
Tick one box.
\begin{itemize}
\item the number of outer shell electrons \Box
\item the difference between the neutron and proton number \Box
\item the oxidation state \Box
\item the type of isotope \Box
\end{itemize} [1]
(iii) Tannins are polymers.
What do you understand by the term \textit{polymer}?
................................................................................................................................................................
................................................................................................................................................................ [2]
(d) One of the carboxylic acids present in ink is gallic acid.
The structure of gallic acid is shown below.

(i) On the structure above, put a ring around the carboxylic acid functional group. [1]
(ii) Gallic acid is a good reducing agent.
What do you understand by the term \textit{reduction}?
................................................................................................................................................................ [1]

A student wants to separate the coloured pigments in a plant leaf by chromatography. He grinds the plant leaf and separates the solids from the green solution.
(a) What method can he use to separate the solids from the solution?
............................................................................................................................................................... [1]
(b) The student takes a drop of the green solution and puts a spot of it onto a piece of chromatography paper. From the diagrams below choose the letter for the most suitable piece of apparatus for this task.

letter ........................................................ [1]
(c) The student sets up the chromatography apparatus as shown.
(i) Label the diagram to show:
• the solvent,
• the original position of the spot of green solution,
• the chromatography paper.

[3]
(ii) How many different pigments were present in the plant leaf?
............................................................................................................................................................... [1]

(d) The structure of some organic compounds found in plant leaves are shown below.

(i) Which one of these compounds is an unsaturated hydrocarbon?
............................................................................................................................................................... [1]
(ii) Describe a chemical test for an unsaturated hydrocarbon.
test ...........................................................................................................................................................
result .......................................................................................................................................................... [2]
(iii) What do you understand by the term \textit{hydrocarbon}?
............................................................................................................................................................... [1]
(iv) State the name of compound B.
............................................................................................................................................................... [1]
(v) To which homologous series does compound D belong?
............................................................................................................................................................... [1]

Lead is a grey metal.
(a) State two physical properties which are characteristic of metals.
.............................................................................................................................
............................................................................................................................. [2]
(b) To which Group in the Periodic Table does lead belong?
............................................................................................................................. [1]
(c) An isotope of lead has the mass number 208.
Complete the table to show the number of subatomic particles in an atom of this isotope of lead.
Use the Periodic Table to help you.

type of particle | number of particles
electrons
protons
neutrons
[3]
(d) When lead is heated in oxygen, lead(II) oxide is formed.
Write a word equation for this reaction.
............................................................................................................................. [1]
(e) When lead(II) oxide is heated with carbon, lead and carbon monoxide are formed.
$$\text{PbO + C } \rightarrow \text{ Pb + CO}$$
(i) Which substance becomes oxidised during this reaction?
............................................................................................................................. [1]
(ii) Carbon monoxide is a covalent compound.
Which one of these statements about carbon monoxide is correct?
Tick ​one ​​box.
It is a solid with a high melting point. [ ]
It conducts electricity when it is a liquid. [ ]
It is a gas at room temperature. [ ]
It forms about 1 % of the atmosphere. [ ] [1]

Three forms of carbon are diamond, graphite and Buckminsterfullerene.


(a) (i) State one difference in structure between Buckminsterfullerene and diamond.
............................................................
............................................................ [1]

(ii) State two differences in structure between graphite and diamond.
............................................................
............................................................
............................................................ [2]

(b) State the type of bonding between the carbon atoms in diamond.
............................................................
............................................................ [1]

(c) Suggest why graphite is used as a lubricant. Refer to the layers in your answer.
............................................................
............................................................
............................................................ [1]

(d) State one use for diamond.
............................................................
............................................................ [1]

(e) Coal is a fuel containing carbon. When coal is burnt, carbon dioxide is produced. Explain how the increase in carbon dioxide concentration in the atmosphere affects the world's climate.
............................................................
............................................................
............................................................ [2]

(f) Coal also contains small amounts of sulfur. Explain how burning coal leads to acid rain.
............................................................
............................................................
............................................................ [2]

(g) Methane is a fuel.

(i) Which one of the following is a natural source of methane? Tick one box.

waste gases from respiration in plants [ ]
waste gases from digestion in animals [ ]
gases from photosynthesis in plants [ ]
gases from forest fires [ ]
[1]

(ii) Draw a diagram to show the arrangement of the electrons in a molecule of methane, $CH_4$.
Use
● for an electron from a carbon atom
× for an electron from a hydrogen atom
[1]

(iii) Methane belongs to the alkane homologous series. Name one other alkane.
........................................................ [1]

The diagram shows a rotary kiln used to make lime from limestone.
Limestone is fed in at the top of the kiln and lime comes out at the bottom.
(a) What is the chemical name for lime? [1]
.......................................................................................................................
(b) State the name of the type of chemical reaction that takes place in the rotary lime kiln. [1]
.......................................................................................................................
(c) Suggest why the air coming out of the rotary kiln has a greater percentage of carbon dioxide than the air entering the kiln. [1]
.......................................................................................................................
(d) State one use for lime. [1]
.......................................................................................................................
(e) A student compared the speed of reaction of three metal carbonates.
She measured the volume of gas released using the apparatus shown.
State one thing that must be kept constant if the speeds of these reactions are to be compared in a fair way. [1]
.......................................................................................................................
(f) The graph shows the volume of carbon dioxide released when the three metal carbonates are heated.
(i) Which carbonate produced carbon dioxide the fastest? [1]
.......................................................................................................................
(ii) What volume of carbon dioxide was produced by strontium carbonate in ten minutes? [1]
.......................................................................................................................
(iii) How does the speed of the reaction of these three metal carbonates relate to the position of calcium, strontium and barium in the Periodic Table? [2]
.......................................................................................................................
(g) Describe how hydrochloric acid and limewater can be used to show that carbonate ions are present in calcium carbonate. [3]
.......................................................................................................................