Category: Chemistry

1.04g of sodium hydroxide was dissolved in deionised water and made up to 100cm³ in a volumetric flask.

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

A mean titre of 22.10cm³ 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!

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!)

2.5g of potassium hydroxide was dissolved in deionised water and made up to 250cm³ in a volumetric flask.

25.0cm³ samples were titrated against nitric acid solution of concentraion 0.150 mol dm^-3.

A mean titre of 18.15cm³ 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.

By titration, it was found that an average titre of 9.90cm³ of 1.00 mol dm^-3 solution of potassium carbonate was required to just neutralise a 25.00 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 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 31.40cm³ of 0.200 mol dm^-3 solution of hydrochloric 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

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

What volume (in cm³) of deionised water would you need to add to 60.0cm³ of ethanoic acid to dilute it from a concentration of 0.200 mol dm^-3 into a concentration of 0.180 mol dm^-3?

What volume (in cm³) of deionised water would you need to add to 200cm³ of nitric acid to dilute it from a concentration of 4.00 mol dm^-3 into a concentration of 1.00 mol dm^-3?

Calculate the concentration of iodine in a solution of volume 2.40dm³ that contains 100 g of iodine

I=126.9

Calculate the concentration of HCl in a solution of volume 1.25dm³ that contains 640 g of HCl

H=1 Cl=35.5

Calculate the concentration of Al₂(SO₄)₃ in a solution of volume 4.80dm³ that contains 400 g of Al₂(SO₄)₃

S=32.1 Al=27.0 O=16.0

Calculate the concentration of NH₄NO₃ in a solution of volume 1.40dm³ that contains 50.0 g of NH₄NO₃

N=14.0 O=16.0 H=1.0

Calculate the concentration of CuSO₄ in a solution of volume 250.00cm³ that contains 20.0 g of CuSO₄

S=32.1 Cu=63.5.0 O=16.0

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 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 number of moles of potassium dichromate (VI) in a solution of volume 750.00 cm³ and a concentration of 6.00 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 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 cm³) of 0.00250 mol of neon if the gas is at a temperature of 473K and a pressure of 150000Pa

Calculate the temperature of a sample of oxygen (in ^oC) if 0.900 mol of oxygen has a volume of 9800cm³ and is at a pressure of 900000Pa

Calculate the temperature of a sample of gaseous ammonia (in K) if 10.0 mol of gaseous ammonia has a volume of 420dm³ and is at a pressure of 75kPa

Calculate the temperature of a sample of hydrogen (in K) if 1.00 mol of hydrogen has a volume of 24.0dm³ and is at a pressure of 101000Pa

Calculate the number of moles of gas present at r.t.p in 1.20 dm³ of chlorine.

Calculate the number of moles of gas present at r.t.p in 30.0 dm³ of krypton.

Calculate the number of moles of gas present at r.t.p in 1.00 m³ of neon

0.250g of gas was collected. The volume of gas was recorded as 169 cm³ at a temperature of 373 K and a pressure of 97kPa

Determine the relative formula mass of the chemical.

Calculate the number of moles of aluminium oxide if you have 25.5 g of aluminium oxide

Al=27.0 O=16.0

Calculate the number of moles of nitrogen if you have 7.00 g of nitrogen

N=14.0

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

I=126.9

Calculate the number of moles of Na if you have 11.5 g of Na

Na=23.0

Calculate the mass of aluminium oxide that you would have if you had 6.00 mol of aluminium oxide

Al=27.0 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 anydrous copper (II) sulfate that you would have if you had 6.10 mol of anydrous copper (II) sulfate

S=32.1 Cu=63.5 O=16.0

Calculate the mass of magnesium hydroxide that you would have if you had 1.80 mol of magnesium hydroxide

H=1.0 C=12.0 O=16.0

Calculate the mass of glucose that you would have if you had 1.25 mol of glucose

H=1.0 C=12.0 O=16.0

A piece of magnesium was reacted with an excess of steam. 600cm³ (measured under r.t.p.) of hydrogen were produced.

What was the mass of the piece of magnesium?

How many moles of molecules are present in 0.120 dm³ of oxygen? (all volumes measured at r.t.p.)

P₄O₁₀+ H₂O => H₃PO₄

The empirical formula of a compound:

sulfur dichloride

Calculate the number of moles of fluorine molecules (F₂) in 9.00g of fluorine

Calculate the number of moles of nitrogen molecules (N₂) in 28.0g of nitrogen

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

Calculate the mass of 0.500 mol of sulfur atoms

Calculate the relative molecular mass (formula mass) of ethene C₂H₄

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

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

If the molecule shown below is hydrolysed in hot sodium hydroxide, what are the main organic products?

In which of these reactions between pairs of reagents is the bond breaking homolytic?

(i) butan-1-ol with sodium bromide and concentrated sulfuric acid

(ii) catalytic cracking of hydrocarbons

(iii) bromine with ethene

(iv) bromine with hexane

The decomposition of dinitrogen pentoxide gas into nitrogen and oxygen is first order with respect to N₂O₅. The units of the rate constant are:

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

What are the units of k for this reaction?

Consider the following reaction:

2NO_(g) + O_2(g) => 2NO_2(g)

The rate equation was found, by experiment:

rate = k [NO_(g)]² [O_2(g)]

Which of the following statements is/are true?

(i) Doubling [O₂] has no effect on the rate of the reaction

(ii) Doubling both [NO] and [O₂] quadruples the rate of the reaction

(iii) Tripling [NO] triple the rate of the reaction

(iv) The mechanism may have only one step

In the anti-cancer complex compound [Pt(NH₃)₂Cl₂]

(i) the Pt, N and Cl atoms lie in one plane

(ii) the N-Pt-N angle is 180^o

(iii) the Cl-Pt-Cl angle is 90^o

(iv) the coordination number of platinum is zero

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)?

Can MnO₄^-_(aq) oxidise water into H₂O_2(aq) in acidic condition?

High resistance voltmeters are required for accurate values of E^ϴcell/V to be measured.

What statement best describes the reasoning behind the use of a high resistance voltmeter?

What is the value of E^ϴcell/V observed for 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

In the anti-cancer complex compound [Pt(NH₃)₂Cl₂]

(i) the Pt, N and Cl atoms lie in one plane

(ii) the N-Pt-N angle is 180^o

(iii) the Cl-Pt-Cl angle is 90^o

(iv) the coordination number of platinum is zero

In an EDTA complex with a copper(II) ion

(i) there are six ligand molecules,

(ii) there are four dative bonds between oxygen atoms and the metal ion,

(iii) the overall charge on the complex ion is zero,

(iv) there are two dative bonds between nitrogen atoms and the metal ion

Calculate the value of the enthalpy change associated with the following equation?

N_2(g) + 3H_2(g) => 2NH_3(g)

The energy change for this process:

Br_(g) + e^- -> Br^-_(g)is called the:

Consider the synthesis of methanol in the following equilibrium:

CO_(g) + 2H_2(g) <=>CH₃OH_(g)

2.00 mol of CO was mixed with 4.00 mol of H₂ and the mixture sealed in a container. The mixture was left until no further observable change in composition took place. At this point, 1.90 mol of CH₃OH was present in the mixture.

Calculate the value of the mole fraction of CH₃OH present in the mixture under these conditions.

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

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

Nitrogen monoxide gas reacts with oxygen gas to form nitrogen dioxide gas. If the rate of formation of nitrogen dioxide is 1.4 x 10^-5 mol dm^-3, what is the rate of disappearance of oxygen?

This is the ¹H NMR spectrum of:

How many peaks would you expect to see in the ¹³C spectrym of 3-propyl aminobenzene?

Which of these statements is true of a solution of a racemic mixture?

(i) It contains asymmetric molecules,

(ii) It is a mixture of enantiomers,

(iii) It contains equal amounts of optical isomers,

(iv) It rotates the plane of polarised light

Which of these compounds are functional group isomers of

HCO₂CH₂CH₂CH₃?

(i) ethyl ethanoate,

(ii) 2-methylpropanoic acid,

(iii) methyl propanoate,

(iv) butanoic acid

If an amino acid is written as RCHNH₂CO₂H, in which of these amino acids is R a polar group?

(i) HSCH₂CHNH₂CO₂H

(ii) C₆H₅CH₂CHNH₂CO₂H

(iii) HOCH₂CHNH₂CO₂H

(iv) CH₃CHNH₂CO₂H

The main forces which hold a coiled protein chain into an alpha-helix are:

Which of the following molecules is/are examples of 2^o amines?

(i) 

(ii)

(iii) 

(iv) 

What is the organic product when benzene reacts with ethanoyl chloride in the presence of aluminium chloride?

Heating methylbenzene under reflux with excess, alkaline potassium manganate(VII) which is a strong oxidising agent produces:

Ethyl ethanoate is heated under reflux with excess aqueous sodium hydroxide. The resulting solution is distilled. The distillate contains:

Which of these alkenes shows E/Z isomerism?

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

For which of the following equations is the value for standard enthalpy change equal to the standard enthalpy of formation of sodium chloride?

The standard enthalpy change of formation of N₂O_(g) is +82 kJ mol^-1. This shows that

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

(i) graphite

(ii) sulfur

(iii) diamond

(iv) iodine

Which of these compounds consist of molecules which are linear?

(i) water

(ii) beryllium chloride

(iii) sulfur dioxide

(iv) carbon dioxide

Which of these compounds consists of a giant structure of ions?

The amount in moles of iodide ions oxidised by one mole of chlorine molecules is:

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

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 vanadium in the VO²⁺ ion is:

Which of these acids is only slightly ionised in aqueous solution?

(i) hydrochloric acid

(ii) nitric acid

(iii) sulfuric acid

(iv) ethanoic acid

What is the temperature of a 12dm³ sample of gas that contains 7g of nitrogen if it is held at a pressure of 300kPa pressure given that the value of the gas constant R = 8.314 J mol^-1K^-1?:

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

In the formula of water, H-O-H, the lines represent:

(i) shared pairs of electrons

(ii) dative bonds

(iii) covalent bonds

(iv) hydrogen bonds

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 moles of molecules are there in 0.240 g bromine?

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)

Using enthalpies of combustion Δ_cH, calculate the enthalpy change for the hydrogenation of propene:

C₃H_6(g) + H_2(g) => C₃H_8(g)

Select the data from theenthalpies of combustion Δ_cH.

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

Calculate the enthalpy change for the formation of one mole of hydrogen chloride gas from its elements given these average bond enthalpies: H-H bond enthalpy = 435 kJ mol^-1, Cl-Cl bond enthalpy = 243 kJ mol^-1 and H-Cl bond enthalpy = 432 kJ mol^-1

For which of the following equations is the value for standard enthalpy change equal to the standard enthalpy of formation of sodium chloride?

An example of an endothermic change is the:

Which of these ions has the greatest polarising power?

What is the electron configuration of a magnesium atom?

What is the oxidation number of MANGANESE in

MnO₄^-

What is the oxidation number of SULFUR in

SO₄^2-

What is the oxidation number of CHLORINE in

ClO₂

Choose one of the following options:

A compound X with the molecular formula C₄H₁₀O has a broad peak in its IR spectrum at 3500cm^-1.

Oxidation of X with excess potassium dichromate(VI) gives a product Y which is not an acid and does not reduce Fehling's solution.

Y has a strong peak in its IR spectrum at 1700cm^-1.

Identify X and Y. (See also the data in question 9.)

There are two main peaks in the infra-red spectrum of carbon dioxide.

This shows that carbon dioxide molecules:

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:

What is the formula of 2-bromo-3-methylpentane?

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

(i) CH₃CH₂CHOHCH₃

(ii) (CH₃)₃COH

(iii) CH₃CH(CH₃)CH₂OH

(iv) (CH₃)₃CCH₂OH

Why is ethanol a liquid while propane is a gas? (Relative atomic masses: C = 12, H = 1, O = 16)

The members of the homologous series of alkanes:

(i) are all straight-chain compounds

(ii) have the general formula C_nH_(2n + 2)

(iii) have identical chemical properties

(iv) show a regular gradation of physical properties as the number of carbon atoms increases.

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

What is the name for this structure:

CH₃CH(CH₃)CH(CH₃)CH₂CH₃?

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

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

Using enthalpies of formation Δ_fH, calculate the enthalpy change for the following hydration process.

Na₂S₂O_3(s) + 5H₂O_(l) => Na₂S₂O₃•5H₂O_(s)

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.

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

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

(i) magnesium oxide

(ii) silicon dioxide

(iii) potassium fluoride

(iv) silicon chloride

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

Which of these molecules are overall non-polar?

(i) H₂O

(ii) CO₂

(iii) SO₂

(iv) CCl₄

Zinc conducts electricity because:

(i) the metal is polycrystalline

(ii) the atoms are close-packed

(iii) the atoms are in contact with neighbouring atoms

(iv) the bonding electrons are delocalised.

Treating ethanal with hydrogen cyanide in the presence of some KCN and then hydrolysing the product with hot hydrochloric acid (which converts a cyano / nitrile group RCN, to RCOOH) produces:

If the molecule shown below is hydrolysed in hot sodium hydroxide, what are the main organic products?

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

This is the ¹³C NMR spectrum of:

What does the symbol [X] represent?

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

Consider the following equilibrium for the Haber-Bosch process:

3H_2(g) + N_2(g) <=>2NH_3(g)

32.0 mol of H₂ was combined with 12.0 mol of N₂ and the mixture sealed and pressurised in a vessel of volume 2.00 dm³. The mixture was left until no further observable change in composition took place. At this point, 4.00 mol of NH₃ was found to be present in the mixture. The pressure was recorded as 200 000 kPa.

Calculate the value of K_c (in units: mol^-2 dm⁶) under these conditions.

For which of these compounds would expect the best agreement between the values of the lattice energy derived from experimental data (with the help of the Born-Haber cycle) and the values calculated from theory on the assumption that the bonding in the crystals is purely ionic?

Look at the chemical equation below.

CH_4(g) + H₂O_(g)=> CO_(g)+ 3H_2(g)

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

When four bromide ions combine with a cobalt(II) ion

(i) the charge on the complex ion is 2-

(ii) the shape of the complex ion is tetrahedral

(iii) the coordination number of the cobalt atom is 4

(iv) the name of the complex is the tetrabromocobalt (II) ion

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

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 processes are endothermic?

(i) water freezing

(ii) ethanol evaporating

(iii) steam condensing

(iv) wax melting

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

What is/are the bond angle(s) found in iodine trifluoride?

(i) 104.5^o

(ii) 120^o

(iii) 107^o

(iv) 90^o

What is the bond angle found in methane?

A molecule of sulfur hexafluoride, SF₆ is:

During the electrolysis of molten sodium chloride:

(i) sodium metal forms at the negative electrode

(ii) sodium ions are reduced at the cathode

(iii) chloride ions lose electrons at the positive electrode

(iv) chlorine atoms are given off as a gas at the anode

What is the electronic configuration of copper? 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 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