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Date November 2017 Marks available 2 Reference code 17N.2.sl.TZ0.2
Level SL Paper 2 Time zone TZ0
Command term Explain Question number 2 Adapted from N/A

Question

Trends in physical and chemical properties are useful to chemists.

The Activity series lists the metal in order of reactivity.

Explain the general increasing trend in the first ionization energies of the period 3 elements, Na to Ar.

[2]
a.

Explain why the melting points of the group 1 metals (Li → Cs) decrease down the group.

[2]
b.

State an equation for the reaction of phosphorus (V) oxide, P4O10 (s), with water.

[1]
c.

Describe the emission spectrum of hydrogen.

[2]
d.

Identify the strongest reducing agent in the given list.

[1]
e.i.

A voltaic cell is made up of a Mn2+/Mn half-cell and a Ni2+/Ni half-cell.

Deduce the equation for the cell reaction.

[1]
e.ii.

The voltaic cell stated in part (ii) is partially shown below.

Draw and label the connections needed to show the direction of electron movement and ion flow between the two half-cells.

[2]
e.iii.

Markscheme

increasing number of protons

OR

increasing nuclear charge

«atomic» radius/size decreases

OR

same number of shells

OR

similar shielding «by inner electrons»

«greater energy needed to overcome increased attraction between nucleus and electrons»

a.

atomic/ionic radius increases

smaller charge density

OR

force of attraction between metal ions and delocalised electrons decreases

Do not accept discussion of attraction between valence electrons and
nucleus for M2.

Accept “weaker metallic bonds” for M2.

b.

P4O10 (s) + 6H2O (l) → 4H3PO4 (aq)

Accept “P4O10 (s) + 2H2O (l) → 4HPO3 (aq)” (initial reaction).

c.

«series of» lines

OR

only certain frequencies/wavelengths

convergence at high«er» frequency/energy/short«er» wavelength

M1 and/or M2 may be shown on a diagram.

d.

Mn

e.i.

Mn (s) + Ni2+ (aq) → Ni (s) + Mn2+ (aq)

e.ii.

wire between electrodes AND labelled salt bridge in contact with both electrolytes

anions to right (salt bridge)
OR
cations to left (salt bridge)
OR
arrow from Mn to Ni (on wire or next to it)

Electrodes can be connected directly or through voltmeter/ammeter/light bulb, but not a battery/power supply.

Accept ions or a specific salt as the label of the salt bridge.

e.iii.

Examiners report

[N/A]
a.
[N/A]
b.
[N/A]
c.
[N/A]
d.
[N/A]
e.i.
[N/A]
e.ii.
[N/A]
e.iii.

Syllabus sections

Core » Topic 5: Energetics/thermochemistry » 5.1 Measuring energy changes
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Core » Topic 3: Periodicity » 3.2 Periodic trends
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Core » Topic 3: Periodicity
Core » Topic 4: Chemical bonding and structure
Core » Topic 5: Energetics/thermochemistry
Core

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