5070_s18_qp_21
A paper of Chemistry, 5070
Questions:
9
Year:
2018
Paper:
2
Variant:
1
Login to start this paper & get access to powerful tools
1
Choose from the gases to answer the questions. argon carbon dioxide carbon monoxide ethane hydrogen methane neon ozone sulfur dioxide sulfur trioxide Each gas can be used once, more than once or not at all. Which gas: is used to manufacture margarine is used as a food preservative has a molecule that contains only eight atoms is formed from bacterial decay of vegetable matter is formed in photochemical smog completely combusts to form only a gas that turns limewater milky?
10. Chemistry of the environment  →  10.3. Air quality and climate
11. Organic chemistry  →  11.3. Fuels
Open
2
The elements in Group VII of the Periodic Table are called the halogens. Explain why the elements in Group VII have similar chemical properties. A redox reaction happens when chlorine gas is bubbled through aqueous potassium iodide. Cl2+ 2I−I2+ 2Cl −Describe what is observed during this reaction. Use the equation to explain that oxidation takes place in this reaction. Use the equation to explain that reduction takes place in this reaction. Describe the chemical test for chlorine gas. test observation Chlorine reacts with iron to form iron(chloride in a closed container. The pressure of chlorine is increased. Describe and explain what happens to the rate of this reaction. Iron(chloride can act as a catalyst for some reactions. Explain how a catalyst increases the rate of a reaction.
8. The Periodic Table  →  8.3. Group VII properties
Open
3
Barium chloride is a soluble salt and barium sulfate is an insoluble salt. Barium sulfate can be prepared by the reaction between aqueous barium chloride and dilute sulfuric acid. Describe the preparation of a pure, dry sample of barium sulfate from aqueous barium chloride and dilute sulfuric acid. Write the ionic equation, including state symbols, for this reaction. Barium chloride can be prepared by reacting barium carbonate with dilute hydrochloric acid. BaCO3 + 2HCl BaCl2 + H2O + CO2 Excess barium carbonate is reacted with 40.0 cm3 of 1.50 mol / dm3 hydrochloric acid. After purification the percentage yield of barium chloride was 75.0 %. Calculate the mass of barium chloride prepared. Give your answer to three significant figures. [Mr : BaCl2 , 208] mass of barium chloride g A barium ion has the formula 138 56 Ba2+. Complete the table about this ion. subatomic particles number of subatomic particles electrons neutrons protons
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
7. Acids, bases and salts  →  7.3. Preparation of salts
Open
4
This question is about ethanol and ethanoic acid. C C H O H H H ethanol ethanoic acid H H C C H O O H H H Describe the manufacture of ethanol by fermentation. Ethanol can be oxidised by oxygen to form ethanoic acid. Construct the equation for this reaction. A sample of ethanol is heated with ethanoic acid in the presence of concentrated sulfuric acid catalyst. Draw the structure of the product of this reaction. Show all of the atoms and all of the bonds. Ethanol is used as a fuel. C2H5OH + 3O2 3H2O + 2CO2 The complete combustion of one mole of ethanol releases 1350 kJ of energy. A sample of ethanol reacts with excess oxygen to make 0.240 dm3 of carbon dioxide, measured at room temperature and pressure. Calculate the energy released, in kJ, in this reaction. energy released kJ
11. Organic chemistry  →  11.6. Alcohols
11. Organic chemistry  →  11.7. Carboxylic acids
Open
5
Silicon is a non-metal found in Group IV of the Periodic Table. Silicon is manufactured by the reduction of silicon dioxide with carbon. SiO2 + 2C Si + 2CO What is the maximum mass of silicon that can be made from 300 g of silicon dioxide? mass of silicon g Silicon has a giant molecular structure. Suggest two physical properties of silicon. Silane has the molecular formula SiH4. Draw the ‘dot-and-cross’ diagram for silane. You only need to show the outer shell electrons of silicon. Using ideas about structure and bonding, suggest why silane has a low boiling point. Siloxanes are condensation polymers. The partial structure of a siloxane can be represented as shown. Si O O Si O Si CH3 CH3 CH3 CH3 CH3 CH3 O Si CH3 CH3 What is meant by the term condensation polymerisation? Draw the repeat unit of this siloxane. Butene forms an addition polymer called poly. C C H2C CH3 H H H butene Draw a partial structure for poly. You must show at least two repeat units.
2. Atoms, elements and compounds  →  2.6. Giant covalent structures
11. Organic chemistry  →  11.8. Polymers
Open
6
Copper pyrites is an ore containing compounds of copper. One of the compounds in the ore is CuFeS2. Calculate the mass of copper in 20.0 tonnes of CuFeS2. mass of copper tonnes CuFeS2 is heated in air. Copper(oxide, iron(oxide and sulfur dioxide are formed. Construct the equation for this reaction. Copper(oxide can be reduced by heating with carbon to form copper. Construct the equation for this reaction. Copper made by this reduction is impure. Impure copper can be purified using electrolysis. Name the electrolyte used. What are the electrodes made from? positive electrode negative electrode Write the equations for the reactions at both electrodes. positive electrode negative electrode
4. Electrochemistry  →  4.1. Electrolysis
9. Metals  →  9.6. Extraction of metals
Open
7
A scientist investigates the reaction of iron with steam in a closed system. A dynamic equilibrium mixture is established. 3Fe+ 4H2OFe3O4+ 4H2Explain why the concentrations of steam and of hydrogen do not change once the dynamic equilibrium mixture has been established. The pressure of the equilibrium mixture is increased. The temperature of the closed system is kept constant. Predict and explain what will happen, if anything, to the composition of the equilibrium mixture. The temperature of the equilibrium mixture is increased. The pressure within the closed system is kept constant. The position of equilibrium shifts to the left hand side. What conclusion can be made about the enthalpy change of the reaction? Describe and explain what happens to the rate of reaction. Dilute sulfuric acid reacts with Fe3O4 to form three compounds, A, B and C. • A is iron(sulfate. • B is iron(sulfate. • C is a colourless liquid. Name compound C. Construct the equation for this reaction. Describe a chemical test for iron(ions. test observation
6. Chemical reactions  →  6.3. Reversible reactions and equilibrium
9. Metals  →  9.4. Reactivity series
Open
8
Methanesulfonic acid has the structure shown. C H S O O H O H H Write the molecular formula for methanesulfonic acid. Methanesulfonic acid is a stronger acid than ethanoic acid. Explain the meaning of this statement. What is the difference between an aqueous acid and an aqueous alkali, in terms of the ions present? What is the mass of methanesulfonic acid needed to make 150 cm3 of a 0.150 mol / dm3 solution? mass g In a titration, 0.00150 moles of NaOH is exactly neutralised by 0.175 mol / dm3 methanesulfonic acid. One mole of sodium hydroxide reacts with one mole of methanesulfonic acid. Calculate the volume, in cm3, of aqueous methanesulfonic acid needed in this titration. volume cm3 Methanesulfonic acid reacts with magnesium to make a salt and a gas. Name the gas made in this reaction. The formula of the anion in the salt is CH3SO3 −. Write the formula of the salt formed.
7. Acids, bases and salts  →  7.1. The characteristic properties of acids and bases
12. Experimental techniques and chemical analysis  →  12.5. Identification of ions and gases
Open
9
Methylpropane is a saturated hydrocarbon. C H H C C H H H H C H H H H methylpropane Methylpropane reacts with chlorine in the presence of ultraviolet light to give several compounds. One of these compounds has a relative molecular mass of 127. What is the molecular formula of this compound? molecular formula Suggest a structure for this compound. Show all of the atoms and all of the bonds. Another compound formed has the percentage composition by mass: 29.7% carbon; 4.3% hydrogen; 65.9% chlorine. Calculate the molecular formula for this compound. molecular formula A compound is formed when one molecule of methylpropane reacts with five molecules of chlorine. Write the molecular formula for this compound. The structures of propene and cyclopropane are shown. C C C H H H H H H C C H H H CH3 cyclopropane propene These two compounds are isomers of each other. What is meant by the term isomerism? Both compounds are hydrocarbons. What is meant by the term hydrocarbons? Propene is an unsaturated hydrocarbon and cyclopropane is a saturated hydrocarbon. What is the difference between an unsaturated and a saturated hydrocarbon? Describe a chemical test to distinguish between unsaturated and saturated hydrocarbons.
3. Stoichiometry  →  3.1. Formulae
11. Organic chemistry  →  11.1. Formulae, functional groups and terminology
11. Organic chemistry  →  11.4. Alkanes
Open