Questions and Answers of Cambridge International AS And A Level Chemistry

The reaction 2SO2(g) + O2(g) ⇋ 2SO3(g) reaches dynamic equilibrium in a closed vessel. The forward reaction is exothermic. The reaction is catalysed by V2O5.a. Explain the term dynamic
These questions relate to the information in Figure 8.5.a. Why are the concentrations of iodine and hydrogen at equilibrium the same?b. Describe how the depth of colour of the reaction mixture
Use the oxidation number method to balance these equations.a. H2SO4 + HI → S + I2 + H2Ob. HBr + H2SO4 → Br2 + SO2 + H2Oc. V3+ + I2 + H2O → VO2+ + I– + H+
Give the formulae of:a. Sodium chlorate(I)b. Iron(III) oxidec. Potassium nitrate(III)d. Phosphorus(III) chloride.
Aluminium reacts with hydrochloric acid to form aluminium chloride, AlCl3, and hydrogen. This is a redox reaction.a. Explain in term of electrons, what is meant by a redox reaction. b. i. Write
The unbalanced equation for the reaction of sulfur dioxide with bromine is shown below.SO2 + Br2 + H2O→ SO42–+ Br–+ H+a. State the oxidation number of sulfur in:i. SO2 ii. SO42–b. State
Calcium reacts with cold water to form calcium hydroxide, Ca(OH)2, and hydrogen, H2.a. State the oxidation number of calcium in:i. Calcium metalii. Calcium hydroxide.b. State the oxidation number of
In the industrial production of nitric acid the following changes take place to the nitrogen.a. Give the oxidation number of the nitrogen atom in each molecule.b. For each stage, state whether
Suggest why it is difficult to measure the enthalpy change directly when an anhydrous salt is converted to a hydrated salt.
Methane, CH4, is a gas at room temperature.a. Explain why methane is a gas at room temperature.b. Draw a diagram to show the shape of a molecule of methane. On your diagram show a value for the bond
a. Predict the shapes of the following moleculesi. Tetrachloromethane, CCl4ii. Beryllium chloride, BeCl2iii. Phosphorus(III) chloride.b. Draw dot-and-cross diagrams for the following molecules and
Sodium iodide and magnesium oxide are ionic compounds. Iodine and oxygen are covalent molecules.a. Draw dot-and-cross diagrams for:i. Magnesium oxideii. Oxygen.b. How do sodium iodide and iodine
Draw diagrams to show hydrogen bonding between the following molecules:a. Ethanol, C2H5OH, and waterb. Ammonia and waterc. Two hydrogen fluoride molecules.
Explain the following differences in terms of the type of bonding present.a. Aluminium oxide has a melting point of 2980 °C but aluminium chloride changes to a vapour at 178 °C.b. Magnesium
The table lists bond lengths and bond energies of some hydrogen halides.a. What is the relationship between the bond length and the bond energy for these hydrogen halides?b. Suggest why the bond
Draw dot-and-cross diagrams for the following covalently bonded molecules; show only the outer electron shells:a. Ethene, CH2CH2b. Carbon disulfide, CS2.
Draw dot-and-cross diagrams for the ions in the following ionic compounds. Show only the outer electron shells.a. Potassium chloride, KClb. Sodium oxide, Na2Oc. Calcium oxide, CaOd. Magnesium
The table shows the atomic number and boiling points of some noble gases.a. Use ideas about forces between atoms to explain this trend in boiling points.b. Xenon forms a number of covalently bonded
Draw dot-and-cross diagrams for the following covalently bonded molecules. Show only the outer electron shells. Note that in part d the beryllium atom is electron deficient and in part e the
Aluminium chloride, AlCl3, and ammonia, NH3, are both covalent molecules.a. i. Draw a diagram of an ammonia molecule, showing its shape. Show any lone pairs of electrons.ii. State the bond angle in
Electronegativity values can be used to predict the polarity of bonds.a. Explain the term electronegativity.b. The electronegativity values for some atoms are given below:H = 2.1, C = 2.5, F = 4.0,
a. Draw dot-and-cross diagrams to show the formation of a co-ordinate bond between the following:i. Boron trifluoride, BF3, and ammonia, NH3, to form the compound F3BNH3ii. Phosphine, PH3, and a
The diagram below shows part of a giant metallic structure.a. Use this diagram to explain the main features of metallic bonding.b. Explain why metals are good conductors of electricity.c. Explain
a. Draw a dot-and-cross diagram for a molecule of selenium hexafluoride, SeF6. A single selenium atom has six electrons in its outer shell.b. Predict the shape of selenium hexafluoride.
Hydrogen sulfide, H2S, is a covalent compound.a. Draw a dot-and-cross diagram for hydrogen sulfide.b. Draw a diagram of a hydrogen sulfide molecule to show its shape. Show on your diagram:i. The
Answer the following, giving a full explanation in terms of metallic bonding.a. Explain why aluminium has a higher melting point than sodium.b. The thermal conductivity of stainless steel is 82 W
The table shows the type of bonding in a number of elements and compounds.a. Draw a labelled diagram to show metallic bonding.b. Explain why magnesium chloride has a high melting point but bromine
Are the following molecules polar or non-polar? In each case give a reason for your answer. (Electronegativity values: F = 4.0, Cl = 3.0, Br = 2.8, S = 2.5, C = 2.5, H = 2.1)a. Chlorine, Cl2b.
Water is extensively hydrogen bonded. This gives it anomalous (peculiar) properties.a. Explain why ice is less dense than liquid water.b. State two other anomalous properties of water.c. Propanone
a. The boiling points of the halogens are:fluorine –188 °C chlorine –35 °Cbromine +59
Bromine, Br2, and iodine monochloride, ICl, have the same number of electrons. But the boiling point of iodine monochloride is nearly 40 °C higher than the boiling point of bromine. Explain this
The table lists the boiling points of some Group 15 hydrides.a. Explain the trend in the boiling points from phosphine to stibine.b. Explain why the boiling point of ammonia does not follow this
Describe the changes that occur in the closeness and motion of the particles when:a. A solid changes to a liquidb. A liquid changes to a gas.
Four types of structure are:giant moleculargiant ionicgiant metallicsimple moleculara. Give two examples of a giant ionic structure and two examples of a simple molecular structure.b. Explain why
Explain why the intermolecular forces in a sample of helium and neon are very small.
The structures of carbon dioxide and silicon dioxide are shown in the diagram below.Use your knowledge of structure and bonding to explain the following:a. Carbon dioxide is a gas at room
Bromine is a reddish-brown liquid. Some liquid bromine is placed in a closed jar. The bromine starts to evaporate. The colour of the vapour above the liquid bromine becomes darker and darker. After a
Crystals of sodium chloride have a lattice structure.a. Describe a sodium chloride lattice.b. Explain the following properties of sodium chloride.i. Sodium chloride has a high melting point.ii.
Explain the following:a. Why are most metals strong, but ionic solids are brittle?b. Why is an alloy of copper and tin stronger than either copper or tin alone?
The diagram shows some allotropes of carbon.a. Give the name of allotrope a, which has the formula C60.b. Explain in terms of structure and bonding why structure a is gaseous at 800 °C but diamond
The table shows some properties of four elements. Use the data to answer the following questions. (Assume that steel has similar properties to iron.)a. Why is aluminium with a steel core used for
Explain the following properties of silicon(IV) oxide by referring to its structure and bonding.a. It has a high melting point.b. It does not conduct electricity.c. It is a crystalline solid.d. It is
Copy and complete the table below to compare the properties of giant ionic, giant molecular, giant metallic and simple molecular structures. Giant Giant ionic molecular Metallic Simple molecular Two
Suggest, using ideas of structure and bonding, why:a. Buckminsterfullerene, C60, is converted from a solid to a gas at a relatively low temperatureb. Graphene is a good conductor of electricityc.
a. Convert the following temperatures into the kelvin temperature:i. 245 °Cii. –45 °Cb. How many pascals are there in 15 kPa?
This question is about gases.a. What do you understand by the term ideal gas?b. Under what conditions does a gas not behave ideally? Explain your answer for one of these conditions.c. Helium is a
Some chemical reactions involving gases are performed in sealed glass tubes that do not melt at high temperatures. The tubes have thin walls and can easily break. Use the kinetic theory of gases to
Water and bromine are both simple molecular substances.a. Both water and bromine form a lattice structure in the solid state. What do you understand by the term lattice?b. The boiling point of water
a. What is meant by the term ideal gas?b. Under what conditions do real gases differ from ideal gases? Give reasons for your answer.
The table gives data on the physical properties of five substances, a to e.a. Copy the table and fill in the gaps.b. Explain the melting point and electrical conductivity of substance a.c. Explain
a. Calculate the volume occupied by 272 g of methane at a pressure of 250 kPa and a temperature of 54 °C. (R = 8.31 J K–1 mol–1; Mr methane = 16.0)b. The pressure exerted by 0.25 mol of carbon
The uses of metals are often related to their properties.a. Describe the structure of a typical metal.b. Explain why metals are malleable.c. Use the information in the table below to answer the
When 0.08 g of liquid X was vaporised at 100 °C, 23 cm3 of vapour was formed. The atmospheric pressure was 1.02 × 105 Pa. Calculate the relative molecular mass of liquid X.(R = 8.31 J K–1 mol–1)
The diagram shows the structures of graphite and diamond.Use the diagrams and your knowledge of structure and bonding to answer the following questions.a. Explain why both diamond and graphite have
Use the Periodic Table on page 473 to calculate the relative formula masses of the following:a. Calcium chloride, CaCl2b. Copper(II) sulfate, CuSO4c. Ammonium sulfate, (NH4)2SO4d. Magnesium
a. Write equations that describe:i. The 1st ionisation energy of calciumii. The 3rd ionisation energy of potassiumiii. The 2nd ionisation energy of lithiumiv. The 5th ionisation energy of sulfur.b.
Write the simple electronic configuration of the following atoms, showing the principal quantum shells only:a. Sulfur; the atomic number of sulfur, Z = 16b. Magnesium, Z = 12c. Fluorine, Z = 9d.
The sketch graph shows the 13 successive ionisation energies of aluminium.a. Define the term 1st ionisation energy.b. How does the graph provide evidence for the existence of three electron shells in
The table below shows the 1st ionisation energies, ΔHi1, in kJ mol–1, of the elements in Period 3 of the Periodic Table.a. Explain why there is a general increase in the value of ΔHi1 across the
a. The successive ionisation energies of boron are shown in Table 3.3.i. Why is there a large increase between the third and fourth ionisation energies?ii. Explain how these figures confirm that the
a. What do you understand by the term atomic orbital?b. Draw diagrams to show the shape of:i. An s orbitalii. A p orbital.c. Element x has the electronic configuration 1s2 2s2 2p6 3s2
a. The first six ionisation energies of an element are 1090, 2350, 4610, 6220, 37800 and 47300 kJ mol–1. Which group in the Periodic Table does this element belong to? Explain your decision.b. Draw
The 1st ionisation energies of several elements with consecutive atomic numbers are shown in the graph below. The letters are not the symbols of the elements.a. Which of the elements A to I belong to
a. Name the three types of orbital present in the third principal quantum shell.b. State the maximum number of electrons that can be found in each subshell of the third quantum shell.
a. Define the following:i. 1st ionisation energy.ii. 3rd ionisation energy. b. Give the equations representing:i. The 1st ionisation energy of magnesiumii. The 3rd ionisation energy of
Use 1s2 notation to give the electronic configurations of the atoms with the following atomic numbers:a. 16b. 9c. 20
The graph shows a sketch of log10 ionisation energy against number of electrons removed for magnesium. Use this sketch graph to answer the following questions.a. Explain why the first two electrons
Use 1s2 notation to give the electronic configurations for the following elements:a. Vanadium (Z = 23)b. Copper (Z = 29)c. Selenium (Z = 34)
a. The table shows the first five ionisation energies for five elements (A to E). For each one state which group the element belongs to.b. Explain your reasoning behind your answer for element E.c.
a. An element has the electronic configuration 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p5.i. Which block in the Periodic Table does this element belong to?ii. Which group does
a. Define the term 1st ionisation energy.b. Draw a sketch graph to show how log10 ionisation energy for chlorine (atomic number 17) varies when plotted against number of electrons removed.c.
Write electronic configurations for the following ions:a. Al3+ (Z = 13)b. O2– (Z = 8)c. Fe3+ (Z = 26)d. Cu2+ (Z = 29)e. Cu+ (Z = 29)
a. The first ionisation energies of four consecutive elements in the Periodic Table are: sodium = 494 kJ mol–1magnesium = 736 kJ mol–1aluminium = 577 kJ mol–1silicon = 786 kJ mol–1i. Explain
a. i. What do you understand by the term relative atomic mass?ii. A sample of boron was found to have the following % composition by mass:Calculate a value for the relative atomic mass of boron. Give
This question is about two transition metals, hafnium (Hf) and zirconium (Zr).a. Hafnium forms a peroxide whose formula can be written as HfO3.2H2O. Use the Ar values below to calculate the relative
Look at the mass spectrum of germanium, Ge.a. Write the isotopic formula for the heaviest isotope of germanium.b. Use the % abundance of each isotope to calculate the relative atomic mass of
Solid sodium carbonate reacts with aqueous hydrochloric acid to form aqueous sodium chloride, carbon dioxide and water.Na2CO3 + 2HCl → 2NaCl + CO2 + H2Oa. Rewrite this equation to include
a. Use these Ar values (Fe = 55.8, N = 14.0, O = 16.0, S = 32.1) to calculate the amount of substance in moles in each of the following:i. 10.7 g of sulfur atomsii. 64.2 g of sulfur molecules
Hydrocarbons are compounds of carbon and hydrogen only. Hydrocarbon Z is composed of 80% carbon and 20% hydrogen.a. Calculate the empirical formula of hydrocarbon Z.(Ar values: C = 12.0, H =
Use these Ar values: C = 12.0, Fe = 55.8, H = 1.0, O = 16.0, Na = 23.0. Calculate the mass of the following:a. 0.20 moles of carbon dioxide, CO2b. 0.050 moles of sodium carbonate, Na2CO3c. 5.00 moles
When sodium reacts with titanium chloride (TiCl4), sodium chloride (NaCl) and titanium (Ti) are produced.a. Write the balanced symbol equation for the reaction.b. What mass of titanium is produced
Give all answers to 3 significant figures. Ammonium nitrate decomposes on heating to give nitrogen(I) oxide and water as follows:NH4NO3(s) → N2O(g) + 2H2O(l)a. What is the formula mass of
Calculate the percentage by mass of carbon in ethanol, C2H5OH. (Ar values: C = 12.0, H = 1.0, O = 16.0)
Give all answers to 3 significant figures.a. 1.20 dm3 of hydrogen chloride gas was dissolved in 100 cm3 of water.i. How many moles of hydrogen chloride gas are present?ii. What was the concentration
Write the empirical formula for:a. Hydrazine, N2H4b. Octane, C8H18c. Benzene, C6H6d. Ammonia, NH3
Give all answers to 3 significant figures.4.80 dm3 of chlorine gas was reacted with sodium hydroxide solution. The reaction taking place was as follows:Cl2(g) + 2NaOH(aq) → NaCl(aq) + NaOCl(aq) +
The composition by mass of a hydrocarbon is 10% hydrogen and 90% carbon. Deduce the empirical formula of this hydrocarbon.(Ar values: C = 12.0, H = 1.0)
Calcium oxide reacts with hydrochloric acid according to the equation:CaO + 2HCl → CaCl2 + H2Oa. What mass of calcium chloride is formed when 28.05 g of calcium oxide reacts with excess
The empirical formulae and molar masses of three compounds, A, B and C, are shown in the table below. Calculate the molecular formula of each of these compounds.(Ar values: C = 12.0, Cl = 35.5, H =
When ammonia gas and hydrogen chloride gas mix together, they react to form a solid called ammonium chloride.a. Write a balanced equation for this reaction, including state symbols.b. Calculate the
a. Write down the formula of each of the following compounds:i. Magnesium nitrateii. Calcium sulfateiii. Sodium iodideiv. Hydrogen bromidev. Sodium sulfideb. Name each of the following compounds:i.
Write balanced equations for the following reactions.a. Iron reacts with hydrochloric acid to form iron(II) chloride, FeCl2, and hydrogen.b. Aluminium hydroxide, Al(OH)3, decomposes on heating to
Write balanced equations, including state symbols, for the following reactions.a. Solid calcium carbonate reacts with aqueous hydrochloric acid to form water, carbon dioxide and an aqueous solution
Change these full equations to ionic equations.a. H2SO4(aq) + 2NaOH(aq) → 2H2O(aq) + Na2SO4(aq)b. Br2(aq) + 2KI(aq) → 2KBr(aq) + I2(aq)
Write ionic equations for these precipitation reactions.a. CuSO4(aq) + 2NaOH(aq) → Cu(OH)2(s) + Na2SO4(aq)b. Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq)
a. Calculate the concentration, in mol dm–3, of the following solutions: (Ar values: C = 12.0, H = 1.0, Na = 23.0, O = 16.0)i. a solution of sodium hydroxide, NaOH, containing 2.0 g of sodium
a. The equation for the reaction of strontium hydroxide with hydrochloric acid is shown below.Sr(OH)2 + 2HCl SrCl2 + 2H2O25.0 cm3 of a solution of strontium hydroxide was exactly neutralised by
20.0 cm3 of a metal hydroxide of concentration 0.0600 mol dm–3 was titrated with 0.100 mol dm–3 hydrochloric acid. It required 24.00 cm3 of the hydrochloric acid to exactly neutralise the
a. Calculate the volume, in dm3, occupied by 26.4 g of carbon dioxide at r.t.p.(Ar values: C = 12.0, O = 16.0)b. A flask of volume 120 cm3 is filled with helium gas at r.t.p. Calculate the mass of
Boron is an element in Group 13 of the Periodic Table.a. Boron has two isotopes. What do you understand by the term isotope?b. State the number of i protons, ii neutrons and iii electrons in one

Showing 400 - 500 of 512