Category: Chemistry

2.79g of sodium carbonate was dissolved in deionised water and made up to 250cm³ in a volumetric flask.

20.0cm³ samples were titrated against hydrochloric acid solution of concentraion 0.350 mol dm^-3.

A mean titre of 11.80cm³ of hydrochloric acid solution was obtained.

Calculate the percentage purity, by mass, of the original solid. (Don't include the % symbol and give answer to 1 decimal place!)

2.49g of potassium hydroxide was dissolved in deionised water and made up to 250cm³ in a volumetric flask.

20.0cm³ samples were titrated against hydrochloric acid solution of concentraion 0.150 mol dm^-3.

A mean titre of 21.90cm³ of hydrochloric acid solution was obtained.

Calculate the percentage purity, by mass, of the original solid. (Don't include the % symbol and give answer to 1 decimal place!)

1g of sodium hydroxide was dissolved in deionised water and made up to 100cm³ in a volumetric flask.

25.0cm³ samples were titrated against nitric acid solution of concentraion 0.200 mol dm^-3.

A mean titre of 28.25cm³ of nitric acid solution was obtained.

Calculate the percentage purity, by mass, of the original solid. (Don't include the % symbol and give answer to 1 decimal place!)

4.95g of potassium hydrogencarbonate was dissolved in deionised water and made up to 100cm³ in a volumetric flask.

10.0cm³ samples were titrated against sulfuric acid solution of concentraion 0.100 mol dm^-3.

A mean titre of 22.05cm³ of sulfuric acid solution was obtained.

Calculate the percentage purity, by mass, of the original solid. (Don't include the % symbol and give answer to 1 decimal place!)

1.56g of lithium hydroxide was dissolved in deionised water and made up to 250cm³ in a volumetric flask.

25.0cm³ samples were titrated against sulfuric acid solution of concentraion 0.100 mol dm^-3.

A mean titre of 23.20cm³ of sulfuric acid solution was obtained.

Calculate the percentage purity, by mass, of the original solid. (Don't include the % symbol and give answer to 1 decimal place!)

Calculate the pH of a solution created by the addition of 20.0cm³ 0.200 mol dm^-3 potassium hydroxide solution to 50.0 cm³ 0.100 mol dm^-3 nitric acid solution.

Remember to give your answer to 3 sig.fig.

By titration, it was found that an average titre of 19.95cm³ of 0.180 mol dm^-3 solution of nitric acid was required to just neutralise a 10.00 cm³ sample of sodium carbonate solution. Calculate the concentraion of the sodium carbonate solution.

The equation for the reaction is

2HNO_3(aq)+Na₂CO_3(aq)=>2NaNO_3(aq)+H₂O_(aq)+CO_2(g)

By titration, it was found that an average titre of 22.85cm³ of 0.300 mol dm^-3 solution of nitric acid was required to just neutralise a 25.00 cm³ sample of sodium carbonate solution. Calculate the concentraion of the sodium carbonate solution.

The equation for the reaction is

2HNO_3(aq)+Na₂CO_3(aq)=>2NaNO_3(aq)+H₂O_(aq)+CO_2(g)

By titration, it was found that an average titre of 19.10cm³ of 0.250 mol dm^-3 solution of sulfuric acid was required to just neutralise a 10.00 cm³ sample of potassium hydroxide solution. Calculate the concentraion of the potassium hydroxide solution.

The equation for the reaction is

2KOH_(aq)+H₂SO_4(aq)=>K₂SO_4(aq)+H₂O_(aq)

By titration, it was found that an average titre of 23.45cm³ of 0.100 mol dm^-3 solution of sulfuric acid was required to just neutralise a 25.00 cm³ sample of sodium hydroxide solution. Calculate the concentraion of the sodium hydroxide solution.

The equation for the reaction is

2NaOH_(aq)+H₂SO_4(aq)=>Na₂SO_4(aq)+H₂O_(aq)

If you were asked to prepare 500cm³ of 0.500 mol dm^-3 nitric acid from 2.00 mol dm^-3, what volume (in cm³) of nitric acid would you need to dilute with deionised water to achieve a total volume of 500cm³ of diluted solution?

Calculate the concentration of barium nitrate in a solution of volume 19.85cm³ that contains 4.82 g of barium nitrate

Ba=137.3 N=14.0 O=16.0

Calculate the concentration of HCl in a solution of volume 2.70dm³ that contains 590 g of HCl

H=1 Cl=35.5

Calculate the concentration of Al₂(SO₄)₃ in a solution of volume 4.80dm³ that contains 250 g of Al₂(SO₄)₃

S=32.1 Al=27.0 O=16.0

Calculate the concentration of NH₃ in a solution of volume 900cm³ that contains 100 g of NH₃

N=14.0 H=1.0

Calculate the concentration of ammonium nitrate in a solution of volume 800cm³ that contains 28.0 g of ammonium nitrate

N=14.0 O=16.0 H=1.0

Calculate the concentration of copper (II) sulfate in a solution of volume 33.00cm³ that contains 1.04 g of copper (II) sulfate

S=32.1 Cu=63.5.0 O=16.0

Calculate the volume of solution in dm³ that would contain 0.120 mol of MgCl₂ if the concentration of the solution is 0.400 mol dm^-3

Calculate the volume of solution in cm³ that would contain 0.750 mol of sodium hydroxide if the concentration of the solution is 6.00 mol cm^-3

Calculate the volume of solution in dm³ that would contain 0.500 mol of NaCl if the concentration of the solution is 2.00 mol dm^-3

Calculate the volume of gas (in dm³) of 0.400 mol of neon if the gas is at a temperature of 0^oC and a pressure of 50.0kPa

Calculate the volume of gas (in dm³) of 1.20 mol of sulfur hexafluoride if the gas is at a temperature of 750K and a pressure of 150kPa

Calculate the volume of gas (in dm³) of 1.40 mol of sulfur hexafluoride if the gas is at a temperature of 3000K and a pressure of 1000kPa

Calculate the volume of gas (in cm³) of 0.0500 mol of neon if the gas is at a temperature of 273K and a pressure of 505000Pa

Calculate the temperature of a sample of methane (in K) if 6.00 mol of methane has a volume of 34.2dm³ and is at a pressure of 150000Pa

Calculate the temperature of a sample of hydrogen (in ^oC) if 1.00 mol of hydrogen has a volume of 24.00dm³ and is at a pressure of 101000Pa

Calculate the number of moles of gas present at r.t.p in 240 cm³ of fluorine.

Calculate the number of moles of gas present at r.t.p in 5.95 m³ of fluorine.

Calculate the number of moles of gas present at r.t.p in 3.00 dm³ of gaseous ammonia.

Calculate the number of moles of gas present at r.t.p in 1200 cm³ of oxygen.

Work out the formula of each of the following molecular compounds.

Use a Periodic Table

hydrogen iodide

Calculate the relative molecular mass (formula mass) of lithium carbonate, Li₂CO₃

Calculate the number of moles of propene if you have 105 g of propene

C=12.0 H=1.0

Calculate the number of moles of anydrous copper (II) sulfate if you have 12.0 g of anydrous copper (II) sulfate

S=32.1 Cu=63.5 O=16.0

Calculate the number of moles of chlorine if you have 15.8 g of chlorine

Cl=35.5

Calculate the number of moles of I₂ if you have 127 g of I₂

I=126.9

Calculate the number of moles of C₆H₁₂O₆ if you have 3.60 g of C₆H₁₂O₆

H=1.0 C=12.0 O=16.0

Calculate the mass of phosphorus (V) oxide (P₄O₁₀) that you would have if you had 1.25 mol of phosphorus (V) oxide (P₄O₁₀)

P=31.0 O=16.0

Calculate the mass of iron (II) sulfate heptahydrate that you would have if you had 0.800 mol of iron (II) sulfate heptahydrate

S=32.1 Fe=55.8 O=16.0 H=1.0

Calculate the mass of sodium that you would have if you had 3.00 mol of sodium

Na=23.0

Barium hydroxide solution will neutralise hydrochloric acid according to the equation

Ba(OH)₂+2HCl =>BaCl₂+2H₂O

What volume of 0.1mol dm^-3 Ba(OH)₂ will neutralise 1 dm³ of 0.1mol dm^-3 HCl?

Zinc metal reacts with hydrochloric acid

Zn+ 2HCl=>ZnCl₂+H₂

How many moles of Zn will react with 10cm3 of 4mol dm^-3 HCl?

How many moles of sodium ions are contained in 1dm³ of 2mol dm^-3 sodium sulfate (Na₂SO₄) solution?

A 2 mol dm^-3 solution of sodium chloride (NaCl) contains

Given this equation,

2CO+O₂=>2CO₂

what mass of CO will react with 32g of oxygen?

K + Cl₂ = KCl

How many moles of CO₂ are contained in 33.0g of the compound?

Calculate the volume in cm³ of 0.100 mole of osmium atoms (density of Os = 22.5gcm^-3) Osmium is the most dense of all the elements

Calculate the relative molecular mass (formula mass) of silver sulphate, Ag₂SO₄

Calculate the relative atomic mass (to one decimal place) of element, C if element C is a mixture of two isotopes, ⁸⁵C and ⁸⁷C, with the abundances 72.15% and 27.85% respectively.

Which of the listed liquids reacts with sodium borohydride NaBH₄ in a nucleophilic addition reaction?

(i) CH₃CH₂OH

(ii)CH₃COCH₃

(iii)CH₃CO₂H

(iv)CH₃CHO

What is the reagent used to convert benzene to nitrobenzene?

Methane reacts with chlorine in the presence of ultraviolet light. The reactive chemical species which attacks methane molecules during the reaction is:

The reaction of hydrogen gas with nitrogen monoxide gas is first order with respect to H_2(g) and second order with respect to NO_(g). It follows that:

(i) rate = k[H_2(g)][NO_(g)]²

(ii) doubling the concentration of NO_(g) increases the rate by a factor of 4

(iii) the overall order of reaction is 3

(iv) halving the concentration of hydrogen reduces the rate by a factor of 1.

What are the units of k for this reaction?

[1] s^-1

[2] mol^-1 dm³ s^-1

[3] mol^-2 dm⁶ s^-1

[4] mol^-3 dm⁹ s^-1

By inspection of this experimental data, what is the rate equation for this reaction?

These are four values for the hydration enthalpies of ions:

-361 kJ mol^-1, -559 kJ mol^-1, -2003 kJ mol^-1, -2537 kJ mol^-1.

These ions from left to right are:

Which of the following can act as a bidentate ligand in the formation of complexes with metal ions?

(i) S₂O₃^2-

(ii) C₂O₄^2-

(iii) SCN^-

(iv) H₂NCH₂CH₂NH₂

Work out the ratio of the species in the following half-equation.

S₂O₃^2- => S₄O₆^2- + e^-

What solution concentrations are required for the determination of a standard cell potential, E^ϴcell/V?

What is the value of E^ϴcell/V observed for a cell constructed from the following half-cells?

Fe³⁺_(aq) + e^- <=> Fe²⁺_(aq) E^ϴ/V = +0.77

MnO₄^-_(aq) + 8H⁺_(aq) + 5e^- <=> Mn²⁺_(aq) + 4H₂O_(aq) E^ϴ/V = +1.51

What is the value of E^ϴcell/V observed for a cell constructed from the following half-cells?

V³⁺_(aq) + e^- <=> V²⁺_(aq) E^ϴcell/V = -0.26

VO₂⁺_(aq) + 2H⁺_(aq) + e^- <=> VO²⁺_(aq) + H₂O_(l) E^ϴcell/V = +1.00

Thinking carefully about the definitions of anode and cathode in electrochemical cells, an anode is defined as (CARE!):

Work out the ratio of the species in the following half-equation.

S₂O₃^2- => S₄O₆^2- + e^-

Which of these complex ions have a colour in solution?

(i) [Sc(H₂O)₃]²⁺

(ii) [CuCl₂]^-

(iii) [Zn(OH)₄]^2-

(iv) [Co(H₂O)₆]²⁺

The compound with the formula K₃[Fe(CN)₆]

(i) is potassium hexacyanoferrate(III)

(ii) contains a complex with an octahedral shape

(iii) includes iron in the oxidation state +3

(iv) contains an hexadentate ligand

What enthalpy change is represented by the following equation?

2Na_(s) + ½ O_2(g)=> Na₂O_(s)

Which of these are examples of acid-base reactions according to the Bronsted-Lowry theory.

(i) ZnO_(s)+2H₃O⁺_(aq)->Zn²⁺_(aq)+3H₂O_(l)

(ii) H₂O_(l)+H₂O_(l)->H₃O⁺ _(aq)+ OH^-_(aq)

(iii) NH_3(g)+HBr_(g)->NH₄Br _(s)

(iv) SO_2(g)+H₂O_(l)->H₂SO_3(aq)

Consider the following equilibrium for the reaction that generates hydrogen for use in the Haber-Bosch Process:

CH_4(g) + H₂O_(g) CO_(g) + 3H_2(g)

100 mol of CH₄ was mixed with 100 mol of H₂O and 200 mol of H₂.The mixture was given time to reach equilibrium. At this point, 350 mol of H₂ was present in the mixture. The pressure inside the 1.20 m³ vessel was measured as 400 kPa

Calculate the value of K_c (in units: mol² dm^-6) under these conditions.

Consider the following reaction:

2H₂O_2(g) => 2H₂O_(g)+ O_2(g)

The rate equation was found, by experiment:

rate = k [H₂O₂]

Which of the following statements is/are true?

(i) The mechanism must be multi step

(ii) Doubling [H₂O_{] quadruples the rate of the reaction}

(iii) [H₂O] must be consumed in more than one step

(iv) The mechanism probably has only one step

The two compounds formed on heating 3-bromo-2-methylpentane with KOH in ethanol (which causes elimination!) are:

(i) alkenes,

(ii) position isomers,

(iii) hydrocarbons,

(iv) E/Z isomers

Which of these reagents are nucleophiles?

(i) Br₂

(ii) NH₃

(iii) NO₂⁺

(iv) CN^-

Methane reacts with chlorine in the presence of ultraviolet light. The reactive chemical species which attacks methane molecules during the reaction is:

Which monomer polymerises to form this polymer?

---CH₂CHCl-CH₂CHCl-CH₂CHCl-CH₂CHCl---

Which of these molecules does NOT consist of one or more chains of amino acids?

(i) The hormone insulin

(ii) The filaments in muscle fibres

(iii) The enzyme in saliva, amylase

(iv) The genetic material, DNA

Examples of polymers that contain the amide bond include:

(i) sugars

(ii) DNA

(iii) Terylene^TM(PET)

(iv) proteins

If the paracetamol molecule shown below is hydrolysed in hot dilute hydrochloric acid, what are the main organic products?

Which types of change are involved in this sequence of reactions, though not necessarily in the order listed?

CH₃CO-C₆H₅ -> CH₃CO-C₆H₄-NO₂ -> CH₃CHOH-C₆H₄-NO₂ -> CH₃CH(OCOCH₃)-C₆H₄-NO₂

(i) esterification

(ii) reduction

(iii) nitration

(iv) hydrolysis

The reaction using a mixture of benzene and ethene in the presence of hydrogen chloride and aluminium chloride produces an important intermediate in the manufacture of:

The reagent which converts ethanoic acid to ethanoyl chloride is:

An alkane in petrol is:

All the oxides of the metals Mg, Ca, Sr and Ba:

(i) are basic

(ii) consist of giant structures of ions

(iii) form nitrates when they react with dilute nitric acid

(iv) are freely soluble in water

The total heat capacity of a calorimeter is 2000 J K^-1.

The standard enthalpy of combustion of propane is -2200 kJ mol^-1

Calculate the expected temperature rise on heating the calorimeter by burning 0.0500 mol of fuel from a propane burner assuming that all the energy heats the calorimeter.

Take care with units.

Calculate the value of the standard enthalpy change of formation of methane given that the values for standard enthalpy changes of combustion are -890 kJ mol^-1 for methane, -393 kJ mol^-1 for carbon and -286 kJ mol^-1 for hydrogen gas.

What is the molar mass of calcium hydroxide?

At room temperature, in the crystal lattice of an ionic compound the ions are:

(i) arranged symmetrically

(ii) uncharged

(iii) held together by electrostatic forces

(iv) stationary

Steel and graphite are similar in that they both.

(i) conduct electricity

(ii) are dark grey/black when powdered

(iii) can have high tensile strength

(iv) are brittle

What volume of 0.10 mol dm^-3 hydrochloric acid is needed to neutralise 20.0 cm³ of 0.05 mol dm^-3 barium hydroxide?

In which of these reactions is the first named element reduced:

(i) hydrogen reacting with copper(II) oxide to form copper and water

(ii) iodine reacting with chlorine to form iodine monochloride

(iii) aluminium reacting with chromium(III) oxide to form aluminium(III) oxide and chromium

(iv) iodine reacting with aluminium to form aluminium iodide

The oxidation number of vanadium in the VO²⁺ ion is:

Which of these compounds is an acid?

The ionic equation for a neutralisation reaction is:

The pressure of a gas results from:

Which one of the following is the electron configuration of a group 2 metal atom?

What is the bond angle found in methane?

What is the electron configuration of an oxide ion?

How many sulfate ions are there in 0.01 mol aluminium sulfate?

(The Avogadro constant = 6.02 x 10²³ mol^-1)

The reaction of nitrogen with hydrogen to form ammonia is exothermic. Which of these changes increases the proportion of ammonia in an equilibrium mixture of nitrogen, hydrogen and ammonia.

(i) raising the pressure at constant temperature

(ii) raising the temperature at constant pressure

(iii) decreasing the volume at constant temperature

(iv) adding a catalyst

For which of these equilibria does a change in pressure have no effect on the yield of substances on the right-hand side of the equation?

(i) CH_4(g) + H₂O_(g) <=> 3H_2(g) + CO_(g)

(ii) 2HI_(g) <=> H_2(g) + I_2(g)

(iii) 2SO_2(g) + O_2(g) <=> 2SO_3(g)

(iv) H₂O_(g) + CO_(g) <=> H_2(g) + CO_2(g)

Which of these are examples of heterogeneous equilibria?

(i) CaCO_3(s) <=> CaO_(s) + CO_2(g)

(ii) Fe²⁺_(aq) + Ag⁺_(aq) <=> Fe³⁺_(aq) + Ag_(s)

(iii) 3Fe_(s) + 4H₂O_(g) <=> Fe₃O_2(s) + 4H_2(g)

(iv)Br_2(aq) + H₂O(l) <=> HOBr_(aq) + H⁺_(aq) + Br^-_(aq)

Which of these reactions can be reversed by changing the conditions in a typical advanced chemistry laboratory?

(i) CuSO₄.5H₂O_(s) -> CuSO_4(s) + 5H₂O(l)

(ii) 2Mg_(s) + O_2(g) -> 2MgO_(s)

(iii) NH_3(g) + HCl_(g) -> NH₄Cl_(s)

(iv) CH_4(g) + 2O_2(g) -> CO_2(g) + 2H₂O_(l)

The enthalpy of combustion Δ_cH of butan-1-ol = -2670 kJ mol^-1

Using this figure and data from the 'Selection of Enthalpies of Formation and Combustion' shown above, calculate the enthalpy of formation Δ_fH of liquid butan-1-ol

A Hess Cycle should be drawn to help you calculate this.

If this question was generated from Random Retrieval, this data can also be found in TOOLS>Data Sheets.

The electron configuration of a chloride ion is:

The carbonates of group 2 metals (M):

(i) have the formula of the form MCO₃

(ii) are insoluble in water

(iii) become more difficult to decompose on heating down the group

(iv) decompose on heating to the metal and carbon dioxide

The reaction of calcium with water produces:

What is the oxidation number of OXYGEN in hydrogen peroxide

H₂O₂

Across period 3 from sodium to argon:

(i) the metal with the lowest melting point is sodium

(ii) the element with the highest melting point is silicon

(iii) the non-metal with the lowest melting point is argon

(iv) the melting points of all the non-metals are lower than those of the metals

Choose one of the following options:

How many structural isomers of C₄H₈O are there?

It's really difficult to get all of these structures, so don't panic if you miss some. Just spend some time sketching out all the possibilities and remembering some simple rules, e.g carbon forms 4 bonds, oxygen forms 2 etc. Be creative!

How many structural isomers of C₆H₁₄ are there?

Which of these pairs of compounds react to form 2-bromopropane as one of the products?

(i) prop-1-ene and hydrogen bromide at room temperature

(ii) propane and bromine in ultraviolet light

(iii) propan-2-ol on heating with sodium bromide

(iv) propan-1-ol and hydrogen bromide on heating

What are the conditions for converting 1,2-dichlorethane into ethane-1,2-diol?

Which of these alcohols is a tertiary alcohol?

(i) CH₃CH₂CHOHCH₃

(ii) CH₃CH(CH₃)CHOHCH₃

(iii) CH₃C(CH₃)₂CH₂CHOHCH₃

(iv) (CH₃)₃COH

A 5.6 g sample of a pure alkene with one double bond in its molecules, reacts with 16.0 g bromine. What is the formula of the alkene? (Relative atomic masses: C = 12, H = 1, Br = 80)

[1] C₂H₄

[2] C₄H₈

[3] C₆H₁₂

[4] C₈H₁₆

Name the alkene CH₃CH(CH₃)CH=CHCH₃.

What is the name for this structure:

CH₃CH(CH₃)CH(CH₃)CH₂CH₃?

Which of these alcohols are isomers of butan-1-ol?

(i) CH₃CH₂CHOHCH₃

(ii) (CH₃)₃COH

(iii) CH₃CH(CH₃)CH₂OH

(iv) (CH₃)₃CCH₂OH

Species such as CH₃⁺ and Br⁺ can be detected in a mass spectrum but do not occur in chemical reactions under typical laboratory conditions.

This is because in a mass spectrometer:

What is the oxidation number of BROMINE in

BrO^-

Which of the following increase from left to right along the series Mg - Ca - Sr - Ba?

(i) the thermal stability of the nitrates

(ii) the thermal stability of the carbonates

(iii) the solubility of the hydroxides in water

(iv) the solubility of the sulfates in water

Iodine oxidises thiosulfate ions, S₂O₃^2 -, to S₄O₆^2- . What is the oxidation number (O.N.) change for each sulfur atom?

Which of these are examples of heterogeneous equilibria?

(i) CaCO_3(s) <=> CaO_(s) + CO_2(g)

(ii) Fe²⁺_(aq) + Ag⁺_(aq) <=> Fe³⁺_(aq) + Ag_(s)

(iii) 3Fe_(s) + 4H₂O_(g) <=> Fe₃O_2(s) + 4H_2(g)

(iv)Br_2(aq) + H₂O(l) <=> HOBr_(aq) + H⁺_(aq) + Br^-_(aq)

E represents an atom of an element in the equation: E_(g) -> E⁺_(g) + e^– Which of these statements is/are true:

(i) the element must be a metal

(ii) the enthalpy change for this process is the first ionisation energy of the element

(iii) the element must be a gas at room temperature.

(iv) this process occurs in a mass spectrometer used to analyse the element

A chloride ion and an argon atom have the same:

(i) number of protons

(ii) number of electrons

(iii) atomic number

(iv) electron configuration

An element X has the electron configuration 1s²2s²2p². Element Y has the electron configuration 1s²2s²2p⁵. What is the likely formula of the compound of X and Y?

What is the bond angle found in BeCl₂?

During the synthesis of an ester from a carboxylic acid and an alcohol the extent of conversion of the carboxylic acid to its ester at equilibrium increases if:

(i) the alcohol is added in excess

(ii) concentrated sulfuric acid is added

(iii) the ester distills off from the reaction mixture as it forms

(iv) an acid catalyst is added

What is the systematic name of the following molecule?

CH₃CH₂CH₂C(NH₂)CHCH₃

Mixing poly(chloroethene) with a plasticiser makes is suitable for use as:

(i) window frames

(ii) insulation for electric cables

(iii) water pipes

(iv) waterproof clothing

Which of these procedures is used on a large scale to recover some value from plastic waste?

(i) burning the plastic in incinerators and using the energy to generate electricity

(ii) re-melting the plastic and spinning the melt into fibres

(iii) heating the waste with catalysts but no air to produce feedstocks for the chemical industry

(iv) washing plastic bottles on high-speed automatic machines so that they can be reused.

Step 10:

What are the units of k for this reaction?

By inspection of this experimental data, what is the rate equation for this reaction?

Look at the chemical equation below.

2NaHCO_3(s)=> Na₂CO_3(s)+ H₂O_(g)+ CO_2(g)

By selecting the appropriate data from the ‘Selection of Thermodynamic Data’ in TOOLS, calculate the entropy change, ΔS^Ɵ for the process. Take care with states!

Look at the chemical equation below.

2NaHCO_3(s)=> Na₂CO_3(s)+ H₂O_(g)+ CO_2(g)

Calculate the temperature at which this process becomes feasible.

If this question is from a Random Retrieval, you can also carry out this calculation by first working out values for ΔS^Ɵ and ΔH^Ɵ by selecting the appropriate data from the ‘Selection of Thermodynamic Data’ in TOOLS.

Which first-row d-block metal forms aqueous ions in the +3 state which oxidise iodide ions to iodine?

Which of these changes are redox reactions?

(i) NaCl_(s) + H₂SO_4(l) -> HCl_(g) + NaHSO_4(s)

(ii) NH_3(g) + HCl_(g) -> NH₄Cl_(s)

(iii) CaCO_3(s) -> CaO_(s) + CO_2(g)

(iv) 2HBr_(g) + H₂SO_4 (l) -> Br_2(l) + SO_2(g) + 2H₂O_(l)

The oxidation number of sulfur in sulfuric acid, H₂SO₄, is:

Which of these true statements can help to explain why iodine is a solid while chlorine is a gas at room temperature and pressure?

(i) iodine molecules have a larger surface area than chlorine molecules

(ii) iodine atoms are heavier than chlorine atoms

(iii) the outer shell electrons in iodine atoms are further from the nucleus than they are in chlorine atoms

(iv) the charge on the nucleus of an iodine atom is larger than the charge on the nucleus of a chlorine atom

Which of these materials owe their strength to intermolecular forces?

In which of these molecules do the intermolecular forces arise largely from attractions between temporary dipoles?

Which of these compounds consist of molecules which are linear?

(i) water

(ii) beryllium chloride

(iii) sulfur dioxide

(iv) carbon dioxide

How many chloride ions touch each sodium ion in the crystal structure of sodium chloride?

Which of these sets of properties is that of an ionic compound?

What is the electronic configuration of scandium? Enter your answer in the following format 1s2 2s2 etc. (note the space between each sub-shell!) Follow the aufbau order of sub-shell filling.

Analysis of a sample of potassium in a mass spectrometer shows that it consists of 93.2% potassium 39 and 6.8% potassium-41. What is the relative atomic mass of potassium?