EduNinja
(a)

The carbonates and hydroxides of Group 2 elements show similar trends in thermal stability.
Suggest and explain the variation in the trend in the thermal stability of the Group 2 hydroxides.

[ 3 ]
(a)
(i)

Explain the factors that are responsible for this variation.

[ 3 ]
(b)

Metal peroxides contain the −O−O−-\mathrm{O}-\mathrm{O}^{-}ion.

The peroxides of the Group 2 elements, MO2\mathrm{MO}_{2}, decompose on heating to produce a single gas and the solid oxide, MO, only.

[ 3 ]
(i)

Suggest how the temperature at which thermal decomposition of MO2\mathrm{MO}_{2} occurs varies down Group 2.
Explain your answer.

[ 3 ]
(a)
(i)

How would the value of ΔHr3⊖\Delta H_{\mathrm{r} 3}^{\ominus} compare with the value of ΔHr4⊖\Delta H_{\mathrm{r} 4}^{\ominus} for the similar reaction with Ca(OH)2(aq)\mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{aq}) as shown in reaction 4 ?
Explain your answer.

Ca(OH)2(aq)+2CO2( g)→Ca(HCO3)2(aq)\mathrm{Ca}(\mathrm{OH})_{2}(\mathrm{aq})+2 \mathrm{CO}_{2}(\mathrm{~g}) \rightarrow \mathrm{Ca}\left(\mathrm{HCO}_{3}\right)_{2}(\mathrm{aq})

reaction 4

[ 2 ]
(a)

Nickel carbonate, NiCO3\mathrm{NiCO}_{3}, decomposes on heating.

Use the Data Booklet to explain whether NiCO3\mathrm{NiCO}_{3} will decompose more or less readily than CaCO3\mathrm{CaCO}_{3}.

[ 2 ]
(a)

Explain why the Group 2 nitrates become more stable to heat down the group.

[ 2 ]
(a)

Describe and explain how the solubility of the Group II sulfates varies down the group.

[ 4 ]
[Maximum number: 1]

Iron is a transition element in the fourth period. Iron forms compounds containing the ions Fe2+\mathrm{Fe}^{2+} and Fe3+\mathrm{Fe}^{3+}.

(a)
(i)

Compare the melting point and density of iron with those of calcium, an s-block element in the fourth period.
melting point
density

[ 1 ]
(a)

The carbonates and hydroxides of Group 2 elements show similar trends in thermal stability.
Suggest and explain the variation in the trend in the thermal stability of the Group 2 hydroxides.

[ 3 ]
(a)

The solubility of the Group 2 hydroxides increases down the group.
Explain this trend.

[ 3 ]
(a)

The solubility of the Group 2 sulfates decreases down the group.
Explain this trend.

[ 3 ]
0