Category: Chemistry

18.4g 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 20.20cm³ 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!)

1.45g of succinic acid (C₄H₆O₄), 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 23.40cm³ 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!)

0.368g 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 0.100 mol dm^-3.

A mean titre of 20.75cm³ 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!

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.

Calculate the pH of a solution created by the addition of 20.0cm³ 0.150 mol dm^-3 barium hydroxide (Ba(OH)₂) solution to 60.0 cm³ 0.200 mol dm^-3 hydrochloric acid solution.

Remember to give your answer to 3 sig.fig.

1g of sodium hydroxide was dissolved in deionised water and made up to 250cm³ in a volumetric flask.

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

A mean titre of 22.50cm³ 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!)

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 20.00cm³ of 0.150 mol dm^-3 solution of hydrochloric 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

NaOH_(aq)+HCl_(aq)=>NaCl_(aq)+H₂O_(aq)

By titration, it was found that an average titre of 28.80cm³ of 2.00 mol dm^-3 solution of potassium carbonate was required to just neutralise a 50.00 cm³ sample of sulfuric acid solution. Calculate the concentraion of the sulfuric acid solution.

The equation for the reaction is

K₂CO_3(aq)+H₂SO_4(aq)=>K₂SO_4(aq)+H₂O_(aq)+CO_2(g)

By titration, it was found that an average titre of 45.25cm³ of 0.100 mol dm^-3 solution of hydrochloric acid was required to just neutralise a 20.00 cm³ sample of barium hydroxide solution. Calculate the concentraion of the barium hydroxide solution.

The equation for the reaction is

Ba(OH)_2(aq)+2HCl_(aq)=>BaCl_2(aq)+2H₂O_(aq)

Calculate the concentration of NH₄NO₃ in a solution of volume 0.724dm³ that contains 50.0 g of NH₄NO₃

N=14.0 O=16.0 H=1.0

Calculate the concentration of lithium hydroxide in a solution of volume 1.05dm³ that contains 65.0 g of lithium hydroxide

Li=6.9 O=16.0 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 barium nitrate in a solution of volume 21.95cm³ that contains 0.670 g of barium nitrate

Ba=137.3 N=14.0 O=16.0

Calculate the concentration of FeSO₄ . 7H₂O in a solution of volume 2.40dm³ that contains 380 g of FeSO₄ . 7H₂O

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

Calculate the concentration of sodium hydroxide in a solution of volume 0.75dm³ that contains 30.0 g of sodium hydroxide

Na=23.0 O=16.0 H=1.0

Calculate the volume of solution in cm³ that would contain 0.200 mol of lithium iodide if the concentration of the solution is 0.800 mol cm^-3

Calculate the volume of solution in dm³ that would contain 0.150 mol of chlorate (I) ions if the concentration of the solution is 0.300 mol dm^-3

Calculate the volume of solution in cm³ that would contain 0.150 mol of chlorate (I) ions if the concentration of the solution is 0.150 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 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 0.400 mol of neon if the gas is at a temperature of 0^oC and a pressure of 60000Pa

Calculate the temperature of a sample of ethene (in K) if 0.120 mol of ethene has a volume of 270cm³ and is at a pressure of 400kPa

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 1.72 m³ of xenon.

Calculate the number of moles of gas present at r.t.p in 6000 cm³ of methane.

Calculate the number of moles of gas present at r.t.p in 590 cm³ of fluorine.

Calculate the number of moles of gas present at r.t.p in 380 cm³ of neon

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

0.277g of gas was collected. The volume of gas was recored as 505 cm³ at a temperature of 400 K and a pressure of 130000Pa

Determine the relative formula mass of the chemical.

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 iodine if you have 12.7 g of iodine

I=126.9

Calculate the number of moles of glucose if you have 36.0 g of glucose

H=1.00 C=12.0 O=16.0

Calculate the number of moles of CuSO₄ if you have 479 g of CuSO₄

S=32.1 Cu=63.5 O=16.0

Calculate the number of moles of N₂ if you have 28.0 g of N₂

N=14.0

Calculate the number of moles of H₂O if you have 27.0 g of H₂O

O=16.0 H=1.0

Calculate the number of moles of O₂ if you have 4.00 g of O₂

O=16.0

Calculate the mass of Ba(NO₃)₂ that you would have if you had 0.900 mol of Ba(NO₃)₂

Ba=137.3 N=14.0 O=16.0

Calculate the mass of H₂SO₄ that you would have if you had 0.200 mol of H₂SO₄

S=32.1 H=1.0 O=16.0

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

Na=23.0 O=16.0 H=1.0

What volume (measured under r.t.p.) of hydrogen will be formed if 15.0g of magnesium is reacted with an excess of steam?

What is the volume (in dm³) occupied at room temperature and pressure (r.t.p:298K and 100KPa) of 0.500moles of methane?

Given this equation,

2Al+Fe₂O₃=>Al₂O₃+2Fe

what mass of aluminium would react completely with 320g of iron (lll) oxide?

How many moles of NO₂ can be made by full decomposition of 1 mole of Pb(NO₃)₂ if the equation for this reaction is:

2Pb(NO₃)₂ => 2PbO + 4NO₂ + O₂

CuS

(NH₄)₂S0₄

calcium hydrogencarbonate

Calculate the mass of oxygen having the same number of molecules as 7.10g of chlorine

Calculate the mass of 3.00 mol of phosphorus (P₄) molecules

Calculate the mass of 0.00200 mol of sodium atoms

The reaction mixture must be completely dry during a Friedel-Crafts acylation or alkylation reaction to:

When propene react with hydrogen bromide the main intermediate is:

The activation energy for the reaction of H_2(g) with I_2(g) is 120 kJ mol^-1. The standard enthalpy change for the reaction is +53 kJ mol^-1.

What is the activation energy for the decomposition of hydrogen iodide into its elements?

What is the value of the rate constant, k for this reaction at this temperature?

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:

What enthalpy change is represented by the following equation?

S^-_(g) + e^-=> S^2-_(g)

Which first-row d-block element is used as the catalyst for the addition of hydrogen gas to C=C double bonds?

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

Cu => Cu²⁺ + e^-

Using your half-equations from questions 10 & 11, balance the REDOX equation below.

S₂O₃^2- + I₂ => S₄O₆^2- + I^-

Select the integers that represent the ratio of species in the overall balanced REDOX equation.

If this question appears in a Random Retrieval quiz, you would be best constructing separate half-equations for the species that is oxidised and the species that is reduced prior to working out the overall REDOX equation.

Consider a cell constructed from the following half-cells:

Mg²⁺_(aq) + 2e^- <=> Mg_(s) E^ϴcell/V = -2.37

Ag⁺_(aq) + e^- <=> Ag_(s) E^ϴcell/V = +0.80

If the solution of Mg²⁺_(aq) was 2.00 mol dm^-3, would you expect to see a greater or smaller value of E^ϴcell/V than you would if the cell was set-up under standard conditions?

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

NO₃^- + H⁺ + e^- => NO₂ + H₂O

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

O₂ + e^- + H⁺ => H₂O

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

I₂ + e^- => I^-

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

What enthalpy change is represented by the following equation?

Al²⁺_(g) => Al³⁺_(g) + e^-

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:

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

Consider the following reaction:

2N₂O_5(g) => 4NO_2(g)+ O_2(g)

The rate equation was found, by experiment:

rate = k [N₂O₅]

Which of the following statements is/are true?

(i) Doubling the concentration N₂O₅ caused the rate of production of 4NO₂ to increase by 4 times

(ii) Tripling the concentration N₂O₅ caused the rate of production of O₂ to increase by 3 times

(iii) There are two particles of N₂O₅ involved in the rate determining step

(iv) The mechanism is probably multi step

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

The graph from an experiment to study the decomposition of hydrogen peroxide shows how the concentration of the hydrogen peroxide varied with time at constant temperature.

Time = 0 minutes, [H₂O₂] = 0.020 mol dm^-3

Time = 654 minutes, [H₂O₂] = 0.010 mol dm^-3

Time = 1308 minutes, [H₂O₂] = 0.005 mol dm^-3

This suggests that, under the conditions of the experiment:

(i) the reaction is zero order with respect to hydrogen peroxide

(ii) the concentration after 1962 minutes was 0.0025 mol dm^-3

(iii) the rate of reaction was constant for the first 654 seconds

(iv) the half-life of the reaction was 654 minutes

This is the ¹H NMR spectrum of:

This is the ¹H NMR spectrum of:

This is the ¹H NMR spectrum of:

This is the ¹³C NMR spectrum of:

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 reactions involve heterolytic bond breaking

(i) propene with bromine

(ii) benzene with bromine

(iii) bromobutane with ammonia

(iv) ethane with bromine

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

Which is the most typical reaction of an amine in organic synthesis?

Which of these chemical species are electrophiles that react with the benzene ring

(i) Br⁺

(ii) Na⁺

(iii) NO₂⁺

(iv) H₃O⁺

The reaction mixture must be completely dry during a Friedel-Crafts acylation or alkylation reaction to:

Which of these alkenes shows E/Z isomerism?

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

Which of the following statements describe molecules that are stereo isomers?

(i) molecules whose atoms have a different arrangement in space

(ii) molecules that have the same molecular formula

(iii) molecules in which the atoms are joined to the same neighouring atoms

(iv) molecules which the same atoms but the atoms are bonded in a different order

Which of these statements about atomic and ionic radii are true?

(i) Atomic radii increase down group 2

(ii) Ionic radii increase down group 7

(iii) Atomic radii decrease across period 3

(iv) In period 3 the ionic radii are smaller than the atomic radii

Which of these systems is NOT in a state of dynamic equilibrium?

A small crystal of iodine is dissolved in hexane to give a violet coloured solution. After adding an equal volume of colourless, aqueous potassium iodide and shaking, the system reaches equilibrium with the hexane layer floating on top of the aqueous layer. At equilibrium:

(i) the concentrations of iodine in the two layers are the same

(ii) the iodine in the hexane turns brown

(iii) the iodine molecules stop moving between the two layers

(iv) the concentrations in each layer stop changing

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)

What is the molar mass of calcium hydroxide?

What is the bond angle found in water?

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 is the volume of 0.020 mol oxygen at 27^oC and 100 kPa pressure given that the value of the gas constant R = 8.31 J mol^-1K^-1?

Using the basic rules of VSEPR, what would you expect the bond angle to be in H₂S?

Which of these sets of properties is that of a substance which is molecular?

A chloride ion and an argon atom have the same:

(i) number of protons

(ii) number of electrons

(iii) atomic number

(iv) electron configuration

Calculate the volume of oxygen gas formed on strongly heating 3.40 g sodium nitrate which decomposes according to this equation:

2NaNO_3(s) -> 2NaNO_2(s) + O_2(g)

Assume that the volume of 1 mol of any gas is 24 000 cm³ under the conditions of the experiment.

What is the molecular formula of a hydrocarbon which consists of 82.8% carbon and has a relative molecular mass estimated in the range 50 and 60.

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

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

How many partially filled orbitals are there in the nitrogen atom?

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:

Using enthalpies of combustion Δ_cH, calculate the enthalpy change for the cracking of butane:

C₄H_10(g) => C₂H_6(g) + C₂H_4(g)

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.

Hydrazine burns according to this equation: N₂H_4(g) + O_2(g) -> N_2(g) + 2H₂O_(l)

Calculate the standard enthalpy change for the combustion of hydrazine given that the standard enthalpy of formation of hydrazine is +51 kJmol^-1 and of water is -286 kJ mol^-1

The standard enthalpy of combustion of methane is -890 kJ mol^-1. Calculate the energy given out on burning 3.2 g methane.

A solution of Br₂ and KI were mixed. Then shaken with cyclohexane. Which is correct?

(i) the bromine is reduced

(ii) the cyclohexane layer goes brown

(iii) the cyclohexane layer goes purple

(iv) the iodine is reduced

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

Bubbling carbon dioxide into an aqueous solution of calcium hydroxide produces a white precipitate of:

What is the oxidation number of FLUORINE in

F₂O

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

Which of these true statements help to explain why the values of the first ionisation enthalpies (energies) of the group 1 metals fall down the group from lithium to caesium?

(i) Down the group, the outer electron gets further from the nucleus

(ii) The charge on the nucleus increases down the group

(iii) Greater shielding means that the attraction between the nucleus and the outer electron reduces down the group

(iv) In all the atoms the outer electron is an s-electron

Choose one of the following options:

Choose one of the following options:

Which of the following statements describe molecules that are stereo isomers?

(i) molecules whose atoms have a different arrangement in space

(ii) molecules that have the same molecular formula

(iii) molecules in which the atoms are joined to the same neighouring atoms

(iv) molecules which the same atoms but the atoms are bonded in a different order

The peak with the largest mass to charge ratio in the mass spectrum of an alkane is detected at mass-to-charge ratio = 58.

This shows that the hydrocarbon:

The number of peaks in the mass spectrum of an element indicates the number of:

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?

Which of these alkenes shows E/Z isomerism?

Burning a hydrocarbon fuel such as methane gas in a limited supply of air is dangerous because under these conditions one of the products is:

One mole of an alkane needs 8 moles of oxygen for complete combustion. What is the molecular formula of the alkane?

What is the H-C-H bond angle in ethene?

What type of reaction takes place on passing the vapour of ethanol over hot aluminium oxide? (Water and an alkene are produced)

Which of these alcohols is oxidised to a ketone by a hot acidic solution of potassium dichromate(VI)?

(i) (CH₃)₃COH

(ii) CH₃CH₂CHOHCH₃

(iii) CH₃CH₂CH₂CH₂OH

(iv) CH₃C(CH₃)₂CH₂CHOHCH₃

What is the electron configuration of a magnesium atom?

Which of these properties of magnesium are also properties of beryllium?

(i) It forms a basic oxide

(ii) It forms an ionic chloride

(iii) It reacts with dilute hydrochloric acid

(iv) It forms a stable oxide with the formula MO (where M represents the metal atom)

In which of these solids are there two types of bonding: one strong and one weak?

(i) diamond

(ii) ice

(iii) sodium chloride

(iv) graphite

Dilute hydrochloric acid reacts with:

(i) zinc to form zinc chloride and hydrogen

(ii) copper(II) oxide to form copper(II) chloride and water

(iii) zinc carbonate to form zinc chloride, carbon dioxide and water

(iv) copper to form copper(II) chloride and hydrogen

What is the concentration of a solution of sodium hydroxide that is made by dissolving 20.0g of the solid in water and making the solution up to 250 cm³? (Relative atomic masses: Na = 23, O = 16, H = 1)

Hydrogen is oxidised when it reacts with:

(i) oxygen to form water

(ii) nitrogen to form ammonia

(iii) chlorine to form hydrogen chloride

(iv) sodium to form sodium hydride

What are the reagents and conditions for converting benzene to bromobenzene?

Which is the most typical reaction of an amine in organic synthesis?

What is the repeat unit in the polymer formed from propene?

Which of these polymers would you expect to have the strongest intermolecular (interchain) forces as a result of the presence of polar covalent bonds?

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

(i) cyanide ions

(ii) hydroxide ions

(iii) ammonia molecules

(iv) ammonium ions

This is the ¹H NMR spectrum of:

What value should go in the blank box in the table?

Consider the following homogenius gaseous equilibrium:

ethene + steam <=> ethanol

0.180 mol of ethene as mixed with 1.03 mol of steam and the the mixture heated in the presence of a catalyst. The mixture was sealed in a vessel and allowed to reach equilibrium. At equilibrium, 0.110 mol of ethanol was present in the equilibrium mixture.

Calculate the value of the mole fraction of ethanol present in the mixture under these conditions.

Look at the chemical equation below.

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

Using your answers to Questions 1 and 2, calculate the Gibbs Energy change, ΔG, for the process if it is carried out in an oven at 100^oC.

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.

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

If the solution of Cu²⁺_(aq) was 0.50 mol dm^-3, would you expect to see a greater or smaller value of E^ϴcell/V than you would if the cell was set-up under standard conditions?

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

What is the volume of 0.020 mol oxygen at 27^oC and 100 kPa pressure given that the value of the gas constant R = 8.31 J mol^-1K^-1?

Which of these statements are true for the hydrides of group 5: NH₃, PH₃, AsH₃ and SbH₃:

(i) the molecules decrease in size down the group

(ii) the boiling point of ammonia is higher than expected from the general trend in values down the group

(iii) none of the molecules is polar

(iv) only ammonia is affected by hydrogen bonding

Which of these bonds are polar covalent bonds?

(i) C-C

(ii) H-Br

(iii) N-N

(iv) C=O

Which of these compounds consist of molecules which are linear?

(i) water

(ii) beryllium chloride

(iii) sulfur dioxide

(iv) carbon dioxide

How many shared pairs of electrons are there in an ethene molecule, C₂H₄?

What is the electronic configuration of sodium? 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

What is the electronic configuration of carbon?

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.