Category: Chemistry

0.925g 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 13.75cm³ 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!)

16.1g of citric acid monohydrate (C₆H₈O₇.H₂O), a tribasic acid, was dissolved in deionised water and made up to 250cm³ in a volumetric flask.

10.0cm³ samples were titrated against potassium hydroxide solution of concentraion 0.500 mol dm^-3.

A mean titre of 18.10cm³ of potassium hydroxide 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!)

1.88g of adipic acid (C₆H₁₀O₄), a dibasic acid, was dissolved in deionised water and made up to 100cm³ in a volumetric flask.

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

A mean titre of 24.50cm³ of sodium hydroxide 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 49.0cm³ 0.250 mol dm^-3 barium hydroxide (Ba(OH)₂) solution to 100 cm³ 0.250 mol dm^-3 chloric (VII) 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 21.25cm³ of 2.450 mol dm^-3 solution of sulfuric acid was required to just neutralise a 10.00 cm³ sample of barium hydroxide solution. Calculate the concentraion of the barium hydroxide solution.

The equation for the reaction is

H₂SO_4(aq)+Ba(OH)_2(aq)=>BaSO_4(aq)+2H₂O_(aq)

By titration, it was found that an average titre of 16.25cm³ of 0.500 mol dm^-3 solution of sulfuric acid was required to just neutralise a 10.00 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)

By titration, it was found that an average titre of 21.85cm³ of 0.200 mol dm^-3 solution of potassium hydroxide was required to just neutralise a 10.00 cm³ sample of phosphoric acid solution. Calculate the concentraion of the phosphoric acid solution.

The equation for the reaction is

3KOH_(aq)+H₃PO_4(aq)=>K₃PO_4(aq)+3H₂O_(aq)

By titration, it was found that an average titre of 26.25cm³ of 1.100 mol dm^-3 solution of sulfuric acid was required to just neutralise a 25.00 cm³ sample of barium hydroxide solution. Calculate the concentraion of the barium hydroxide solution.

The equation for the reaction is

H₂SO_4(aq)+Ba(OH)_2(aq)=>BaSO_4(aq)+2H₂O_(aq)

By titration, it was found that an average titre of 20.00cm³ of 1.20 mol dm^-3 solution of nitric acid was required to just neutralise a 25.00 cm³ sample of potassium hydroxide solution. Calculate the concentraion of the potassium hydroxide solution.

The equation for the reaction is

KOH_(aq)+HNO_3(aq)=>KNO_3(aq)+H₂O_(aq)

What volume (in cm³) of deionised water would you need to add to 100cm³ of hydrochloric acid to dilute it from a concentration of 2.00 mol dm^-3 into a concentration of 1.00 mol dm^-3?

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 Ba(NO₃)₂ in a solution of volume 1400cm³ that contains 76.0 g of Ba(NO₃)₂

Ba=137.3 N=14.0 O=16.0

Calculate the concentration of barium nitrate in a solution of volume 22.50cm³ that contains 0.670 g of barium nitrate

Ba=137.3 N=14.0 O=16.0

Calculate the volume of solution in dm³ that would contain 0.0100 mol of manganate (VII) ions if the concentration of the solution is 0.0800 mol dm^-3

Calculate the volume of solution in dm³ that would contain 0.450 mol of Ag⁺ ions if the concentration of the solution is 0.500 mol dm^-3

Calculate the volume of solution in cm³ that would contain 0.300 mol of hydrochloric acid if the concentration of the solution is 1.30 mol cm^-3

Calculate the volume of solution in dm³ that would contain 5.00 mol of glucose if the concentration of the solution is 2.50 mol dm^-3

Calculate the number of moles of potassium chloride in a solution of volume 0.850 dm³ and a concentration of 0.0125 mol dm^-3

Calculate the number of moles of sucrose in a solution of volume 16.25 cm³ and a concentration of 0.100 mol dm^-3

Calculate the volume of gas (in cm³) of 0.150 mol of nitrogen if the gas is at a temperature of 750K and a pressure of 150kPa

Calculate the volume of gas (in cm³) of 0.00250 mol of neon if the gas is at a temperature of 473K and a pressure of 150000Pa

Calculate the volume of gas (in dm³) of 2.00 mol of gaseous ammonia if the gas is at a temperature of 1000K and a pressure of 75000Pa

Calculate the volume of gas (in dm³) of 0.400 mol of helium if the gas is at a temperature of 273K and a pressure of 50000Pa

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 number of moles of gas present at r.t.p in 800 cm³ of propane.

Calculate the number of moles of gas present at r.t.p in 100 dm³ of nitrogen.

Calculate the number of moles of gas present at r.t.p in 12.0 m³ of hydrogen.

Calculate the number of moles of gas present at r.t.p in 52.0 dm³ of carbon dioxide.

Calculate the number of moles of gas present at r.t.p in 12.0 dm³ of hydrogen.

Calculate the number of moles of ethane if you have 6.00 g of ethane

C=12.0 H=1.0

Calculate the number of moles of lithium hydroxide if you have 80.0 g of lithium hydroxide

Li=6.9 O=16.0 H=1.0

Calculate the number of moles of potassium hydrogen carbonate if you have 9.00 g of potassium hydrogen carbonate

K=39.1 H=1.0 C=12.0 O=16.0

Calculate the number of moles of fluorine if you have 76.0 g of fluorine

F=19.0

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

Cl=35.5

Calculate the number of moles of NH₄NO₃ if you have 32.0 g of NH₄NO₃

N=14.0 O=16.0 H=1.0

Calculate the mass of iodine that you would have if you had 0.0500 mol of iodine

I=126.9

Calculate the mass of P₂O₅ that you would have if you had 0.100 mol of P₂O₅

P=31.0 O=16.0

Calculate the mass of Mg(OH)₂ that you would have if you had 1.80 mol of Mg(OH)₂

Mg=24.3 H=1.0 O=16.0

Calculate the mass of CaCO₃ that you would have if you had 1.20 mol of CaCO₃

Ca=40.1 C=12.0 O=16.0

Potassium hydroxide will neutralise nitric acid according to the equation

KOH+ HNO₃=>KNO₃+ H₂O

0.5 litres of 1mol dm^-3 KOH is neutralised by 1 litre of a solution of HNO₃

What is the concentration of the HNO₃?

Zinc metal reacts with hydrochloric acid

Zn+ 2HCl=>ZnCl₂+H₂

What volume of 2mol dm^-3 HCl will react with 2 mol of Zn?

When ammonia gas is passed over heated iron wool it decomposes completely into nitrogen and hydrogen

2NH₃ <=>N₂ + 3H₂

Assume all volumes are measured at the same temperature and pressure.

250cm³ of ammonia was passed, forwards and backwards, over heated iron wool from one graduated syringe to another until there was no further volume change.

What was the final volume of gas in the syringes?

What is the volume (in dm³) occupied at room temperature and pressure (r.t.p:298K and 100KPa) of 1.00 mole of oxygen molecules?

The mass of 1.00 mole of MgSO₄ is:

Ca(NO₃)₂

ZnCl₂

1.00mol of Y₂ molecules weighs 14 times as much as 1 mole of hydrogen molecules. What is the relative atomic mass of Y?

Calculate the number of moles of iron atoms in 55.8g of iron

Calculate the relative molecular mass (formula mass) of copper (II) sulfate pentahydrate CuSO₄ ●5H₂O

Which of these formulae represent glycine in aqueous solution at pH 9?

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

Which of these chemical species are nucleophiles with react with halogenoalkanes?

(i) cyanide ions

(ii) hydroxide ions

(iii) ammonia molecules

(iv) ammonium ions

Which of these types of isomerism are examples of stereoisomerism.

(i) chain isomerism

(ii) E/Zisomerism

(iii) functional group isomerism

(iv) optical isomersim

This is the ¹H NMR spectrum of:

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_p (in units: kPa²) under these conditions.

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

Which of the statements below are true of this reaction?

[Cu(H₂O)₆]²⁺(aq) + 4NH₃(aq) <=> [Cu(NH₃)₄(H₂O)₂]²⁺(aq) + 4H₂O(aq)

(i) Copper disproportionates,

(ii) It is a proton transfer reaction,

(iii) Ammonia is oxidised,

(iv) It is a ligand exchange reaction

For this question, look at the resource, ‘A Selection of Standard Electrode Potentials’ (‘A Selection of Standard Electrode Potentials’can be found in TOOLS>Data Sheets)

Is Cu²⁺_(aq) capable of oxidising Ag_(s)?

Consider a cell constructed from the following half-cells:

Zn²⁺_(aq) + 2e^- <=> Zn_(s) E^ϴ/V = -0.76

Cu²⁺_(aq) + 2e^- <=>Cu_(s) E^ϴ/V = +0.34

Which half-cell will form the cathode in this cell? Think very carefully about the definition of a cathode!

For this question, look at the resource, ‘A Selection of Standard Electrode Potentials’ (‘A Selection of Standard Electrode Potentials’can be found in TOOLS>Data Sheets)

When nitric(V)acid is added to a purple solution of V²⁺_(aq) ions and the mixture allowed to stand for a few minutes, what colour will be observed in the solution?

Using oxidation numbers (states) work out the ratio of the species in the following half-equation.

H₂SO₄ + H⁺ + e^- => SO₂ + H₂O

What enthalpy change is represented by the following equation?

2Na_(s) + ½ O_2(g)=> Na₂O_(s)

For which of these changes is the enthalpy change the standard enthalpy of atomisation of bromine?

What is the pH of a 0.01 mol dm^-3 solution of methanoic acid given that for this acid: K_a = 1.6 x 10^-4 mol dm^-3 at 298K ?

What is the pH of a 0.01 mol dm^-3 solution of sodium hydroxide given that Kw = 1.0 x 10^-14 mol²dm^-6 at 298K?

Consider the following equilibrium:

N_2(g) + O_2(g) <=>2NO_(g)

5.00 x 10^-3 mol of N₂ was mixed with 4.00 x 10^-3 mol of O₂ and 11.0 x 10^-3 mol of NO and the mixture sealed in a container. The volume of the container was 0.500 dm³. The mixture was left to form a stable equilibrium. At this point, 9.00 x 10^-3 mol of NO was present in the mixture. The pressure was recorded as 45000 kpa

Calculate the value of K_c (no units) under these conditions.

Consider the following reaction:

2NO_2(g) + F_2(g) => 2NO₂F_(g)

The rate equation was found, by experiment:

rate = k [NO₂] [F₂]

Which of the following statements is/are true?

(i) The mechanism has more than one step

(ii) Doubling [NO₂] doubles the rate of the reaction

(iii) NO₂ is produced in one of the steps

(iv) The mechanism has only one step

Which graph represents the disappearance of a reactant that displays first order kinetics?

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

This is the ¹H NMR spectrum of:

This is the ¹H NMR spectrum of:

Which of these compounds have E/Z isomers?

(i) pent-2-ene,

(ii) 2-methylpent-2-ene,

(iii) 1,2-dichloropropene,

(iv) hex-1-ene

Which of these compounds are chain isomers of 2-methylpentane

(i) hexane,

(ii) 2,2-dimethylpentane,

(iii) 2,3-dimethylbutane,

(iv) 2,2-dimethylpropane

Which statement helps to explain why propene react with hydrogen bromide to form mainly 2-bromopropane and much less 1-bromopropane?

The monomer which polymerises to form a plastic which has a smooth, slippery surface and is used to give cooking utensils a non-stick surface is:

The formation of a molecules of polythene from CH₂=CH₂ involves many thousands of:

What is the reagent used to convert benzene to nitrobenzene?

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

(i) CH₃CH₂OH

(ii)CH₃COCH₃

(iii)CH₃CO₂H

(iv)CH₃CHO

A compound P, C₄H₈O, gave on oxidation an acid C₄H₈O₂. Which of the following are possible structures for P?

(i)CH₃CH₂CH₂CHO

(ii)CH₃COCH₂CH₃

(iii) (CH₃)₂CHCHO

(iv) CH₃CH=CHCH₂OH

Which of these organic compounds show a broad absorption peak caused by hydrogen bonding affecting a functional group.

(i) propanol

(ii) propanal

(iii) propanoic acid

(iv) propanone

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

What is the oxidation number of SULFUR in

SO₄^2-

What is the oxidation number of OXYGEN in hydrogen peroxide

H₂O₂

The total O.N. of all the halogen atoms in these compounds ClO^-, BrO^-, ICl, XeF₄ is:

The value that you obtain for the enthalpy of combustion Δ_cH of liquid ethanol using mean bond enthalpies is different from the value obtained experimentally, or by using enthalpy of formation Δ_fH of liquid ethanol.

What is the most significant reason for this?

When iron(II) chloride solution mixes with silver nitrate solution some silver metal precipitates and the mixture reaches an equilibrium state.

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

When the aqueous layer is decanted off, the precipitate of silver redissolves on adding a solution of:

Which of these materials consist of a giant structure of ions?

(i) magnesium oxide

(ii) silicon dioxide

(iii) potassium fluoride

(iv) silicon chloride

Which of these elements consist of a giant structure of atoms joined by covalent bonding?

(i) graphite

(ii) sulfur

(iii) diamond

(iv) iodine

In which of these elements are the atoms or molecules closely packed but free to move around sliding past each other at room temperature?

(i) mercury

(ii) argon

(iii) bromine

(iv) iodine

Which of these conversions are reductions?

(i) CrO₄^2- to Cr₂O₇^2-

(ii) CrO₄^2- to Cr³⁺

(iii) CrO₄^2- to CrO₃

(iv) CrO₃ to Cr₂O₃

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?

Which of these compounds dissolve in water and react to form a solution containing hydroxide ions:

(i) sodium oxide

(ii) ammonium chloride

(iii) ammonia

(iv) sodium chloride

Which of these compounds is an acid?

Which of the following is not a typical property of most metals:

What is the bond angle found in BF₃?

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

A chloride ion and an argon atom have the same:

(i) number of protons

(ii) number of electrons

(iii) atomic number

(iv) electron configuration

How many filled orbitals are there in the neon atom?

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?

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.

Using enthalpies of formation Δ_fH, calculate the enthalpy of combustion Δ_cH of ethanol:

C₂H₅OH_(l) + 3O_2(g) => 2CO_2(g) + 3H₂O_(l)

Select the data from the 'Selection of Enthalpies of Formation and Combustion' shown above.

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

The energy needed to atomise 1 mol of gaseous ethene, C₂H₄ is 2087 kJ mol^-1. Calculate the average bond enthalpy for a C-H bond given that the bond enthalpy for the C=C bond is +347 kJ mol^-1.

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.

Which of these ions has the greatest polarising power?

What is the oxidation number of CARBON in methanol

CH₃OH

What is the oxidation number of NITROGEN in

NH₄⁺

What is the oxidation number of OSMIUM in

OsO₄

What is the oxidation number of SULFUR in

SO₃

What is the oxidation number of CARBON in

CO₂

Infra-red absorption ranges for some bonds are as follows:

C-H, 2850 - 3300 cm^-1

C=C, 1620 - 1680 cm^-1

C=O, 1680 - 1750 cm^-1

C-O, 1000 - 1300 cm^-1

O-H (alcohols), 3230 - 3550 cm^-1

O-H (acids), 2500 - 3000 cm^-1

The IR spectrum of propanal has one particularly strong absorption peak

This can be expected to be at:

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:

Which is the correct sequence of events that takes place in a modern mass spectrometer in the production of a mass spectrum from a sample of an element or compound?

Which reagent can be used to convert butan-1-ol to but-1-ene?

An alcohol consists of 64.9% carbon, 13.5% hydrogen and 21.6% oxygen.

What is the molecular formula of the compound? (Relative atomic masses: C = 12, H = 1, O = 16)

What is the product of the reaction of but-2-ene with steam in the presence of a phosphoric acid catalyst?

The reagent which converts hex-1-ene to dibromohexane is:

Which of these alkenes shows E/Z isomerism?

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

(i) CH₃CH₂CHOHCH₃

(ii) (CH₃)₃COH

(iii) CH₃CH(CH₃)CH₂OH

(iv) (CH₃)₃CCH₂OH

This procedure produces a white precipitate which dissolves easily in dilute ammonia solution: heating C₄H₉X for a few minutes with aqueous alkali, then acidifying the mixture with dilute nitric acid and adding silver nitrate. This shows that X is:

Choose one of the following options:

What is the oxidation number of SULFUR in

S₂O₃^2-

When chlorine reacts with cold, aqueous sodium hydroxide the ions formed are:

Which of the following increase from left to right across the series F₂ - Cl₂ - Br₂?

(i) covalent radius of the atoms

(ii) electronegativitiy

(iii) boiling point

(iv) strength as an oxidising agent

Using mean bond dissociation enthalpies, estimate the enthalpy of combustion Δ_cH of liquid ethanol

C₂H₅OH_(l) + 3O_2(g) => 2CO_2(g) + 3H₂O_(l)

A molecule of sulfur hexafluoride, SF₆ is:

Which of these materials owe their strength to intermolecular forces?

The pressure of a gas results from:

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:

What is the systematic name of the following molecule?

CH₃CH₂CH₂C(NH₂)CHCH₃

Which of these molecules are polar?

(i) trans but-2-ene,

(ii) trans 1,2-dichloroethene,

(iii) cis but-2-ene,

(iv) cis 1,2-dichloroethene

This is the ¹H NMR spectrum of:

The reaction of bromine with propanone in acid solution is zero order with respect to bromine, first order with respect to propanone and first order with respect to hydrogen ions.

At a given temperature, the rate of disappearance of bromine is 1.20 x 10^-4 mol dm^-3 when

[CH₃COCH₃] = 0.30 mol dm^-3

[Br₂] = 0.05 mol dm^-3

[H+] = 0.10 mol dm^-3

What is the rate of disappearance bromine when

[CH₃COCH₃] = 0.10 mol dm^-3

[Br₂] = 0.10 mol dm^-3 and [H+] = 0.05 mol dm^-3?

What are the units of k 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!

Which of these complex ions acts as an acid in aqueous solution?

(i) [Ni(NH₃)₆]²⁺

(ii) [Al(H₂O)₂(OH)₄]^-

(iii) [Ag(NH₃)₂]⁺

(iv) [Cr(H₂O)₆]3⁺

Using oxidation numbers (states) work out the ratio of the species in the following half-equation.

ClO^- + H⁺ + e^- => Cl^- + H₂O

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

O₂ + e^- + H⁺ => H₂O

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?

The pressure of a gas results from:

Which of these processes are endothermic?

(i) water freezing

(ii) ethanol evaporating

(iii) steam condensing

(iv) wax melting

Which of these elements has a relatively low boiling point (below 500 ^oC)?

In the family of hydrocarbons called alkanes:

(i) the boiling points of the straight chain compounds rise as the number of carbon atoms increases

(ii) the intermolecular forces arise from attractions between temporary dipoles

(iii) in any pair of isomers the compound with the more highly branched molecules has the lower boiling point

(iv) the unbranched compounds are all liquids at room temperature.

What is the bond angle found in methane?

An ammonia molecule, NH₃, can react to form an ammonium ion, NH₄⁺. When this happens:

(i) the ammonia molecule forms a bond with a proton

(ii) the ion formed has a tetrahedral shape

(iii) a dative covalent bond forms

(iv) the H-N-H bond angle is 90^o

A 20.0 cm³ sample of barium hydroxide solution, Ba(OH)_2(aq), was neutralised by exactly 18.0 cm³ of 0.10 mol dm^-3 hydrochloric acid, HCl_(aq). What was the concentration of the barium hydroxide solution?

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?