Chemistry Random Retrieval Y13

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

Which of these compounds are solids at room temperature?

(i) propane

(ii) propanoic acid

(iii) propylamine

(iv) 2-aminopropanoic acid

In which of these organic compounds are all the bonds non-polar?

(i) 1-bromobutane

(ii) butene

(iii) butan-2-ol

(iv) butane

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

Consider the following equilibrium:

3Fe_(s) + 4H₂O_(g) Fe₃O_4(s)+ 4H_2(g)

40.0 g of iron wool was placed in a vessel of volume 2.00 dm³. The iron was exposed to 20.0 mol of high pressure steam and the system allowed to settle to equilibrium. At equilibrium, 0.250 mol of hydrogen was found in the vessel. The gauge on the pressure vessel read 1 000 kPa. The volume of iron wool was insignificant.

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

What enthalpy change is represented by the following equation?

Cl_(g) + e^-=> Cl^-_(g)

Look at the chemical equation below.

CH_4(g) + H₂O_(g)=> CO_(g)+ 3H_2(g)

Calculate the temperature at which this process just 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.

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

BrO₃^- + H⁺ + e^- => Br^- + H₂O

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

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)

Which chemical species is most resistant to reduction?

What temperature is required for the determination of a standard cell potential, E^ϴcell/V?

[1] 298K

[2] 20^oC

[3] 273K

[4] 298 ^oC

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 pieces of tin (Sn) are added a yellow solution of acidified ammonium vanadate(V) containing the VO₂⁺_(aq) ion 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.

S₂O₃^2- => S₄O₆^2- + e^-

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

Cr₂O₇^2- + H⁺ + e^- => Cr³⁺

+H₂O

Which first-row d-block element forms an oxide used as the catalyst in the synthesis of sulfur trioxide from sulfur dioxide and oxygen?

Which first-row d-block metal forms hydrated ions in the +3 state which undergo a ligand exchange reaction to form a deep red complex ion with thiocyanate ions, SCN^-.

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 entropy change, ΔS^Ɵ for the process. Take care with states!

The magnitude (numerical value) of the lattice enthalpy for these compounds increase from left to right putting first the compound with the least negative value?

(i) LiCl - LiBr - LiI

(ii) MgO - BaO - BaS

(iii) NaCl - KCl - RbCl

(iv) NaF - MgF₂ - AlF₃

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_p (in units: kPa^-2) under these conditions.

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?

Which of these compounds can exist in two enantiomeric forms?

(i) 2-methylbutan-1-ol,

(ii) 2-bromo-1-chlorobutane,

(iii) 2-chloropentane,

(iv) 1-chlorobutane

Which of these compounds are functional group isomers of

HCO₂CH₂CH₂CH₃?

(i) ethyl ethanoate,

(ii) 2-methylpropanoic acid,

(iii) methyl propanoate,

(iv) butanoic acid

Step 8:

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.

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

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

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

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

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

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

(i) CH₃CH₂OH

(ii)CH₃COCH₃

(iii)CH₃CO₂H

(iv)CH₃CHO