Chemistry Year 13 Random Retrieval

Which types of alcohol, when heated under reflux with acidified potassium dichromate(VI), turn the colour of the solution from orange to green?

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

NOT ON OCR SPEC. Hint: Esters can be hydrolysed and the initial stage in the mechanism is nucleophilic attack using an oxygen lone pair of the water molecule. RO^- is the leaving group and becomes ROH.

¹⁸O is a ‘radiolabelled oxygen’.

The reaction of ethyl ethanoate with H₂¹⁸O produces:

Which of these types of isomerism are examples of stereoisomerism.

(i) chain isomerism

(ii) E/Zisomerism

(iii) functional group isomerism

(iv) optical isomersim

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

Consider the following reaction:

C₄H₉Cl_(aq) + OH^-_(aq) => C₄H₉OH_(aq) + Cl^-_(aq)

The rate equation was found, by experiment:

rate = k [C₄H₉Cl]

Which of the following statements is/are true?

(i) Increasing the concentrations of all reactants speeds up the nucleophilic substitution reaction

(ii) The mechanism probably has only one step

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

(iv) OH^- is required for the overall reaction to proceed

A mixture of 1 mol ethanoic acid and 1 mol ethanol was allowed to reach equilibrium at a constant temperature. Analysis of the equilibrium mixture showed that it contained ¹/₃ mol ethanoic acid and ¹/₃ mol ethanol:

CH₃CO₂H_(l) + C₂H₅OH_(l) <=> CH₃CO₂C₂H_5(l) + H₂O_(l)

What is the value of K_c?

At a given temperature, which of these expressions have a constant value for all equilibrium mixtures of hydrogen, iodine vapour and hydrogen iodide?

(i) [H₂]/[I₂],

(ii) [HI]²/[H₂][I₂],

(iii) [I₂]/[H₂]

(iv) [H₂][I₂]/[HI]²

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

NO₃^- + H⁺ + e^- => NO₂ + H₂O

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