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Bismuth is an element in Group 15 of the Periodic Table.
(a) Bismuth has metallic bonding.
Draw a labelled diagram to show the metallic bonding in bismuth.
(b) Bismuth reduces water to form bismuth oxide, $Bi_2O_3$. A colourless gas that ignites with a squeaky pop also forms.
(i) Construct an equation for the reduction of water by bismuth.
.......................................................................................................................... [1]
(ii) $Bi_2O_3$ is a yellow insoluble solid that melts at $1090 K$. The molten compound conducts electricity.
Deduce the structure and bonding of $Bi_2O_3$. Explain your answer.
.......................................................................................................................... [2]
(c) $Bi_2O_3$ can be used to form $NaBiO_3$, as shown in equation 1.
equation 1 $$Na_2O + Bi_2O_3 + O_2 \rightarrow 2NaBiO_3$$
(i) Deduce the oxidation number of Bi in $Bi_2O_3$ and in $NaBiO_3$.
oxidation number of Bi:
in $Bi_2O_3$ ................................................... in $NaBiO_3$ ................................................... [1]
(ii) Identify the reducing agent in equation 1.
.......................................................................................................................... [1]
(d) $NaBiO_3$ is an oxidising agent with similar properties to $KMnO_4$.
Fig. 1.1 shows an example of the use of $NaBiO_3$ as an oxidising agent.
[Image_1: Fig. 1.1 shows the reaction of X with $NaBiO_3$ forming Y and Z.]
(i) Explain the term oxidising agent.
.......................................................................................................................... [1]
(ii) Compound X forms when methylbut-2-ene reacts with $KMnO_4$.
State the essential conditions for this reaction.
.......................................................................................................................... [1]
(iii) Complete Table 1.1 to show what is observed when compounds Y and Z react separately with the named reagents.
[Table_1: Table 1.1 showing different reagents and observations with Y and Z.]
reagent | observation with Y | observation with Z
$Na_2CO_3(aq)$ | no reaction |
alkaline $I_2(aq)$ | |
2,4-dinitrophenylhydrazine (2,4-DNPH) | |
Tollens' reagent | |
[4]
(iv) Construct an equation for the reaction of Z with $NaBH_4$.
Use [H] to represent an atom of hydrogen from the reducing agent.
.......................................................................................................................... [1]
(e) $NaBiO_3$ can be used to determine the concentration of $Mn^{2+}(aq)$. The ionic equation for the reaction is shown in equation 2.
equation 2 $$2Mn^{2+} + 5BiO_3^- + 14H^+ \rightarrow 2MnO_4^- + 5Bi^{3+} + 7H_2O$$
A student uses the following procedure in an experiment.
• Add $100.0 cm^3$ of a saturated solution of $Mn^{2+}(aq)$ to a volumetric flask.
• Add distilled water to the flask to make a $1.00 dm^3$ diluted solution.
• Titrate a $25.00 cm^3$ sample of the diluted solution with $0.100 mol dm^{-3}$ $NaBiO_3(aq)$.
The $25.00 cm^3$ sample of the diluted solution of $Mn^{2+}(aq)$ reacts completely with exactly $21.50 cm^3$ of $0.100 mol dm^{-3}$ $NaBiO_3(aq)$.
Calculate the concentration, in $mol dm^{-3}$, of $Mn^{2+}(aq)$ in the saturated solution.
Show your working.
concentration of $Mn^{2+}(aq)$ in the saturated solution = .............................................. $mol dm^{-3}$ [3]
[Total: 16]
575
582
594
Chlorine, $Cl_{2}$, reacts with many elements and compounds to form chlorides.
Table 2.1 shows information about some chlorides of Period 3 elements.
Table 2.1
[Table_1]
(a) Complete Table 2.1.
(b) When $Cl_{2}$ reacts with cold $NaOH(aq)$, $Cl_{2}$ is both oxidised and reduced. The products are $NaCl$, water and $G$.
(i) State the type of redox reaction in which the same species is both oxidised and reduced. [1]
.................................................................................................................................
(ii) Identify $G$. [1]
.................................................................................................................................
(iii) Write an equation for the reaction between $Cl_{2}$ and hot $NaOH(aq)$. [1]
.................................................................................................................................
(iv) Describe fully what is observed when $AgNO_{3}(aq)$ is added to the aqueous solution of the chloride of sodium, followed by dilute $NH_{3}(aq)$. [2]
.................................................................................................................................
(c) An excess of $Cl_{2}$ reacts with phosphorus to form $PCl_{5}$.
(i) $PCl_{5}$ is a simple molecule in the gas phase.
It also exists in a solid form as two ions, $PCl_{4}^{+}$ and $PCl_{6}^{-}$.
Complete Table 2.2 to identify the shapes of each of these species. [2]
Table 2.2
[Table_2]
(ii) $PCl_{5}$ reacts with $J$ to form $H_{3}PO_{4}$.
Identify $J$ and state the type of reaction. [2]
$J$ .................................. type of reaction .......................................................
(d) $Cl_{2}$ reacts readily with propene to form $K$, 1,2-dichloropropane.
$K$ can be used to form $L$.
(i) Complete Fig. 2.2 to show the mechanism for the reaction of $Cl_{2}$ with propene in reaction 1. Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate. [4]
(ii) Identify the reagent and conditions for reaction 2. [1]
.................................................................................................................................
(iii) Draw one repeat unit of the addition polymer that forms from $L$. [1]
.................................................................................................................................
523
538
533
Nitrogen, $N_2$, is generally an unreactive molecule but it does react under certain conditions.
(a) Give two reasons to explain the lack of reactivity of nitrogen.
..............................................................................................................................................................
(b) $N_2$ can react with oxygen in an internal combustion engine to form a mixture of $NO$ and $NO_2$. Fig. 3.1 shows a reaction scheme involving $N_2$.
(i) Write an equation to show the formation of a mixture of $NO$ and $NO_2$ in reaction 1.
..............................................................................................................................................................
(ii) Give the formulae of the products of reaction 2.
..............................................................................................................................................................
(iii) State one environmental consequence of reaction 3.
..............................................................................................................................................................
(c) The Haber process involves the reaction of $N_2$ and $H_2$ to form ammonia, $NH_3$. A catalyst is used, which allows the process to be carried out at a lower temperature and pressure. $$ N_2(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) \quad \Delta H = -92 \text{kJ mol}^{-1} $$
(i) Use the information in (c) to complete Table 3.1.
[Table_1]
(ii) Explain how the presence of a catalyst affects the reaction.
..............................................................................................................................................................
(iii) State and explain the effect, if any, on the rate of the Haber process as the pressure is lowered.
..............................................................................................................................................................
(d) The $N_2F_2$ molecule has a double covalent bond between its nitrogen atoms. This consists of a $\sigma$ and a $\pi$ bond.
(i) Complete Fig. 3.2 to show the dot-and-cross diagram for $N_2F_2$. Show outer electrons only.
(ii) Deduce the hybridisation of the N atoms in $N_2F_2$.
..............................................................................................................................................................
(iii) Draw a diagram of the $\pi$ bond between the N atoms in $N_2F_2$ and describe how it forms.
..............................................................................................................................................................
[Total: 15]
535
538
594
(a) P, Q, R and S show stereoisomerism.
Complete Table 4.1 by identifying with a tick (✓) the type of stereoisomerism that each molecule shows.
The type of stereoisomerism shown by Q is given.
(b) (i) Give the structural formula of Q.
.............................................................................................................................................. [1]
(ii) Name the mechanism in reaction 2.
.............................................................................................................................................. [1]
(iii) Complete the equation for reaction 3. R is represented as C₄H₉CN.
C₄H₉CN + ................................................................................................................................. [1]
(c) Compounds S and T react to form organic compound U, which has a single functional group.
Table 4.2 shows some data from the mass spectrum of U.
(i) Use the data from Table 4.2 to show that U contains 7 carbon atoms.
Show your working.
[2]
(ii) Fig. 4.2 shows the infrared spectrum of U.
Use Fig. 4.2 and Table 4.3 to identify the functional group present in U.
Explain your answer fully.
functional group ............................................................................................................................
explanation ................................................................................................................................
[2]
(iii) T also has a single functional group.
Use the information in (c)(i) and your answer to (c)(ii) to identify T and U.
Draw the structures of T and U in the boxes.
[2]
[Total: 11]
509
529
501
