Chemistry Year 13 Random Retrieval

This quiz contains all the questions in the year 13 chemistry section. The website will pick 10 questions at random.

1 / 10

Which types of change are involved in this sequence of reactions, though not necessarily in the order listed?

CH₃CO-C₆H₅ -> CH₃CO-C₆H₄-NO₂ -> CH₃CHOH-C₆H₄-NO₂ -> CH₃CH(OCOCH₃)-C₆H₄-NO₂

(i) esterification

(ii) reduction

(iii) nitration

(iv) hydrolysis

(i), (ii) and (iii)

(i) and (iii) only

(ii) and (iv) only

(iv) alone

2 / 10

Which of these statements defines a free radical?

an uncharged species

a species with an unpaired electron

an intermediate in a multi-step reaction

a species formed by breaking a covalent bond

3 / 10

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

rate = k [B]¹

rate = k [A]¹

rate = k [A]¹ [B]¹

rate = k [A]¹ [B]²

4 / 10

Consider the following equilibrium:

H_2(g) + I_2(g)<=>2HI_(g)

1.50 mol of HI was placed in a sealed vessel and allowed to decompose. At equilibrium, 0.500 mol of HI remained in the vessel

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

0.250

0.25

0.333

0.05

5 / 10

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.

0.0700

0.100

0.920

0.110

6 / 10

Why does the term [H₂O_(l)]not appear in the expression for K_a for methanoic acid?

The concentration of [H₂O_(l)]= 1.0

Methanoic acid does not react with water

The extent of ionisation of the acid is very, very small

In a dilute solution the concentration of water is effectively constant

7 / 10

The value of K_a for ethanoic acid = 1.7 x 10^-5 mol dm^-3 (pK_a = 4.8). During a titration of 20.0cm³ 0.1 mol dm^-3 solution of ethanoic acid with 0.1 mol dm^-3 sodium hydroxide, what is the pH of the mixture in the flask after adding 10.0 cm³ of the alkali?

1.4

2.4

3.2

4.8

8 / 10

What enthalpy change is represented by the following equation?

Mg²⁺_(g) + 2F^-_(g) => MgF₂ _(s)

enthalpy of formation, ∆_fH

lattice enthalpy, ∆_LEH

2nd Electron Affinity, ∆_ea2H

bond dissociation enthalpy, ∆_bH

9 / 10

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

3Rb_(g)=> 3Rb_(s)

-80.9

80.9

-243

243

10 / 10

Thinking carefully about the definitions of anode and cathode in electrochemical cells, an anode is defined as (CARE!):

positive electrode where reduction takes place.

positive electrode where oxidation takes place.

negative electrode where oxidation takes place.

negative electrode where reduction takes place.

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