O-LevelChemistryBonding & Structure5070/21 · Oct/Nov 2014 · Q210 Marks

The table shows some properties of the Group 0 elements (noble gases). | element | density of liquid element in g/cm³ | boiling point /°C | |:--------|:---------------------------------|:------------------| | helium | 0.15 | -269 | | neon | 1.20 | -246 | | argon | 1.40 | -186 | | krypton | | -152 | | xenon | 3.52 | |

(a)Predict
(a)(i)the density of liquid krypton,[1]
(a)(ii)the boiling point of xenon.[1]
(b)Argon is a gas at room temperature.
(b)(i)Describe the arrangement and motion of the particles in a gas. arrangement motion[2]
(b)(ii)State one use of argon.[1]
(c)The noble gases are unreactive. Explain why.[1]
(d)Several compounds of the noble gases have been made in recent years. Xenon(IV) fluoride, XeF4, reacts with water to form a mixture which contains xenon, xenon(VI) oxide, XeO3, and hydrogen fluoride, HF. Complete the equation for the reaction of xenon(IV) fluoride with water. ..... XeF4 + .... H₂O → Xe + 2XeO3 + 12HF[1]
(e)The noble gases make up about 1% of the air. Describe and explain how fractional distillation can be used to separate the gases in the air.[3]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2014). The mark or mark type is shown in brackets.

[1] (a)(i) values between 1.6 and 2.6 (1) (actual value = 2.15)
[1] (a)(ii) values between –130 and – 80 (1) (actual value = –107)
[2] (b)(i) arrangement: is random/irregular (1) motion: rapid/fast/can move anywhere/random (1)
[1] (b)(ii) any suitable use e.g. in steelmaking/in light bulbs/welding (1)
[1] (c) completely filled outer shells of electrons/not able to gain electrons/not able to lose electrons/not able to share electrons (1)
[1] (d) 3XeF4 + 6H2O → Xe + 2XeO3 + 12HF (1)
[3] (e) ANY THREE FROM air liquefied (1) temperature of liquefied air raised (gradually)/liquid air is heated (1) gas with lowest boiling point vaporises first (1) idea of fractionation depending on difference in boiling points (1) idea of fractionation depending differences in size (or mass) of the atoms or molecules (1)

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