Chemistry Random Retrieval Y13

A sample of propan-2-ol was heated under reflux with an acidified, aqueous solution of potassium dichromate(VI). The resulting mixture was then distilled. The distillate contained:

(i) propanoic acid

(ii) propanone

(iii) propanal

(iv) water

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

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

Step 6:

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

How many peaks would you expect to see in the ¹³C spectrym of 2,5-dimethyltetrahydrofuran?

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.

What enthalpy change is represented by the following equation?

Mg²⁺_(g) + 2F^-_(g) => MgF_2 (s)

Using your half-equations from questions 4 & 5, balance the REDOX equation below.

BrO₃^- + H⁺ + C₂O₄^2- => CO₂ + Br^- + H₂O

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.

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.

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

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

The extent to which the negative ions are polarised by neighbouring positive ions in these crystals increase from left to right in which of these series?

(i) KF - KCl - KBr

(ii) LiI - NaI - KI

(iii) NaBr - MgBr₂ - AlBr₃

(iv) MgF₂ - CaF₂ - SrF₂

Consider the values of the equilibrium constant for this reversible reaction:

H_2(g) +I_2(g) <=> 2HI_(g)

Temperature: 500K, value of K_c = 160

Temperature: 1000K, value of K_c = 54.

This information shows that:

(i) HI decomposes rapidly at 500 K

(ii) Raising the temperature causes the equilibrium to shift to the left

(iii) Raising the pressure causes the equilibrium to shift to the right

(iv) The reaction is exothermic

Consider the following equilibrium:

N_2(g) + O_2(g) <=>2NO_(g)

1.80 x 10^-3 mol of N₂ was mixed with 2.40 x 10^-3 mol of O₂ and 7.20 x 10^-3 mol of NO and the mixture sealed in a container. The mixture was left until no further observable change in composition took place. At this point, 4.80 x 10^-3 mol of O₂ was present in the mixture.

Calculate the value of the mole fraction of O₂ present in the mixture under these conditions.

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.

Consider the following equilibrium:

PCl_3(g) + Cl_2(g) <=> PCl_5(g)

6.00 mol of PCl₃was mixed with 6.00 mol of Cl₂ and the mixture sealed in a vessel and allowed to reach equilibrium. At equilibrium, 2.00 mol of PCl₅ was present in the equilibrium mixture.

Calculate the value of the mole fraction of PCl₅ present in the mixture 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

What are the units of k for this reaction?

For which of these reactions can the rate of reaction be studied by collecting one of the products over water in a graduated tube (or measuring cylinder) inverted in a trough of water?

(i) Na₂SO_3(s) + 2HCl_(aq) -> 2NaCl_(aq) + SO_2(g) + H₂O_(l)

(ii) Zn_(s) + H₂SO_4(aq) -> H_2(g) + ZnSO_4(aq)

(iii) 2KCl_(s) + H₂SO_4(l) -> KHSO_4(s) + HCl_(g)

(iv) CaCO_3(s) + 2HNO_3(aq) -> Ca(NO₃)_2(aq) + CO_2(g) + H₂O_(l)

This is the ¹H NMR spectrum of:

Which of these types of isomerism are examples of stereoisomerism.

(i) chain isomerism

(ii) E/Zisomerism

(iii) functional group isomerism

(iv) optical isomersim

Free-radical intermediates in the reaction of chlorine with methane include:

(i) CH₃^.

(ii) H^.

(iii) Cl^.

(iv) C^.

Which of these changes represents a termination step of a chain reaction?

(i) CH₃^. + CH₃^. -> CH₃CH₃

(ii) CH₃^. + Br₂ -> CH₃Br + Br^.

(iii) Br^. + Br^. -> Br₂

(iv) Br^. + CH₄ -> CH₃^. + HBr

Step 7:

Which of these amino acids are chiral?

(i) CH₃CHNH₂CO₂H

(ii) C₆H₅CH₂CHNH₂CO₂H

(iii) HOCH₂CHNH₂CO₂H

(iv) CH₂NH₂CO₂H

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

What is the main organic product when benzene reacts with 2-iodo-2-methylpropane in the presence of aluminium chloride?

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:

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