No questions found
(a) Complete Table 1.1 using relevant information from the Periodic Table.
Table 1.1
| | nucleon number | proton number | number of electrons |
|-----------------|----------------|---------------|---------------------|
| $\text{Mg}^{2+}$ | 24 | | |
| $\text{Al}^{3+}$ | 27 | | |
[2]
(b) State and explain the difference in the ionic radius of $\text{Al}^{3+}$ compared to $\text{Mg}^{2+}$.
...............................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................................
[3]
(c) Draw a labelled diagram to show the structure and bonding in sodium.
[1]
(d) Fig. 1.1 shows the variation in melting point of some Period 3 elements in their standard states at room temperature and pressure.
Fig. 1.1
(i) Explain why Si has a high melting point.
.................................................................................................................................................................................................................................................................
[1]
(ii) Complete Fig. 1.1 to show the variation in the melting points of the elements P, S and Cl.
[2]
(e) Two Period 3 elements react with an excess of oxygen at room pressure.
(i) Complete Table 1.2.
Table 1.2
| Period 3 element | state of oxide at room temperature and pressure | approximate pH of solution made when oxide is added to water |
|------------------|---------------------------------------------|-----------------------------------------------------------|
| Na | | |
| S | | |
[2]
(ii) The solutions made in column 3 of Table 1.2 are mixed together.
Name the type of reaction that occurs.
....................................................................................................................................
[1]
(iii) Write an equation to describe the reaction between $\text{P}_4\text{O}_{10}$ and an excess of water.
...................................................................................................................................................................
[1]
(f) Aluminium hydroxide is amphoteric.
(i) Explain what is meant by amphoteric.
.................................................................................................................................................................................................................................................................
[1]
(ii) Write an equation to describe the reaction that occurs when aluminium hydroxide, $\text{Al}(\text{OH})_3$, reacts with NaOH(aq).
...................................................................................................................................................................
[1]
596
578
524
Separate samples of $Na_2CO_3$ and $NaHCO_3$ react with $HCl(aq)$ to produce the same products, as shown in Table 2.1.
[Table_1]
(a) Complete the reaction pathway diagram in Fig. 2.1 for reaction 2.
Label the diagram to show the enthalpy change, $\Delta H_2$, and the activation energy, $E_A$.
(b)The value for $\Delta H_1$ is determined by experiment using the following method.
- 50.0 $cm^3$ of 2.00 $mol \, dm^{−3}$ $HCl(aq)$ is added to a polystyrene cup.
- The initial temperature of the acid is recorded as 19.6°C.
- 0.0400 $mol$ of $Na_2CO_3$ is added and the mixture is stirred.
- All the solid $Na_2CO_3$ disappears and a colourless solution is produced.
The maximum temperature recorded during the reaction is 26.2°C.
(i) Describe one other observation that shows the reaction is complete. .............................................................................................................................. [1]
(ii) Calculate the value of $\Delta H_1$ in $kJ \cdot mol^{-1}$.
Assume the specific heat capacity of the reaction mixture is the same as for water and no heat is lost to the surroundings.
Show your working.
$\Delta H_1 =$ ..................................... $kJ \cdot mol^{-1}$ [3]
(iii) Thermal decomposition occurs when $NaHCO_3$ is heated.
reaction 3 $2NaHCO_3 \rightarrow Na_2CO_3 + H_2O + CO_2$
Calculate the enthalpy change for reaction 3, $\Delta H_r$, using the data in Table 2.1 and the value of $\Delta H_1$ calculated in (b)(ii).
(If you were unable to calculate a value for $\Delta H_1$ in (b)(ii), assume the enthalpy change is −38.4 $kJ \cdot mol^{-1}$. This is not the correct value.)
$\Delta H_r =$ ...................................... $kJ \cdot mol^{-1}$ [2]
(c) $Z$ is a salt that contains a Period 4 element from Group 2. When $Z$ is heated brown gas forms.
Identify the formula of $Z$ and use it to write an equation for the reaction. .............................................................................................................................. [2]
572
521
554
(a) Describe what is meant by dynamic equilibrium.
..............................................................................................................................
..............................................................................................................................
..............................................................................................................................
(b) Reaction 4 describes the reversible reaction between yellow Fe^{3+}(aq) and colourless SCN^-(aq) to produce red FeSCN^{2+}(aq).
reaction 4
Fe^{3+}(aq) + SCN^-(aq) \rightleftharpoons FeSCN^{2+}(aq)
yellow colourless red
An equilibrium mixture contains Fe^{3+}(aq), SCN^-(aq) and FeSCN^{2+}(aq). A few colourless crystals of soluble KSCN(s) are added. The mixture is then left until it reaches equilibrium again. The temperature of both equilibrium mixtures is the same.
(i) Deduce the changes that occur, if any, in the equilibrium mixture after KSCN(s) is added compared to the original equilibrium mixture.
• change in appearance
...............................................................
• change in relative concentration of Fe^{3+}(aq)
...............................................................
• change in value of the equilibrium constant, K_c
...............................................................
(ii) The expression for the equilibrium constant, K_c, for reaction 4 is shown.
K_c = \frac{[FeSCN^{2+}(aq)]}{[Fe^{3+}(aq)] \times [SCN^-(aq)]}
5.00 \times 10^{-5}\text{mol of } Fe^{3+}(aq) and 5.00 \times 10^{-5}\text{mol of } SCN^-(aq) are added together and allowed to reach equilibrium. The total volume of the mixture is 25.0\text{cm}^3.
At equilibrium the concentration of FeSCN^{2+}(aq) is 4.23 \times 10^{-4}\text{mol dm}^{-3}.
Calculate the equilibrium constant, K_c, for reaction 4.
Include the units in your answer.
K_c = .........................................
units = ........................................
(c) Determine the full electronic configuration of Fe^{3+}.
...........................................................................................................
(d) SCN^-(aq) is colourless.
Complete the dot-and-cross diagram in Fig. 3.1 to show the arrangement of outer electrons in an SCN^- ion.
[Image of Diagram: Fig. 3.1]
558
557
512
CH_3(CH_2)_5CHBrCH_3 exists as a pair of stereoisomers.
(a) Draw the three-dimensional structures of the two stereoisomers of CH_3(CH_2)_5CHBrCH_3. R can be used to represent CH_3(CH_2)_5:
[Image of the vertical structure slot]
[2]
(b) A sample of CH_3(CH_2)_5CHBrCH_3 reacts with NaOH to make CH_3(CH_2)_5CH(OH)CH_3 in an $S_N1$ mechanism.
Complete Fig. 4.1 to show the mechanism for the reaction of CH_3(CH_2)_5CHBrCH_3 and NaOH.
Include charges, dipoles, lone pairs of electrons and curly arrows, as appropriate.
[Image of mechanism diagram: CH_3(CH_2)_5CBrCH_3 → CH_3(CH_2)_5COHCH_3]
[3]
(c) Separate samples of CH_3(CH_2)_5CHBrCH_3, CH_3(CH_2)_5CH(OH)CH_3 and CH_3(CH_2)_5CHCH_2 are tested with different reagents.
Complete Table 4.1. If no reaction occurs, write × in the relevant box.
[Table 4.1]
+-----------------------------------------+-------------------------------+-----------------------------------+----------------------------------+
| reagent added | observation with CH_3(CH_2)_5CHBrCH_3 | observation with CH_3(CH_2)_5CH(OH)CH_3 | observation with CH_3(CH_2)_5CHCH_2 |
+-----------------------------------------+-------------------------------+-----------------------------------+----------------------------------+
| Br_2(l) in the dark | | | |
| PCl_5(s) | | | |
| AgNO_3(aq) | | | |
+-----------------------------------------+-------------------------------+-----------------------------------+----------------------------------+
[3]
(d) CH_3(CH_2)_5CHBrCH_3 is heated with D to produce three different molecules, E, F and G.
[Image of molecules E, F, G]
Fig. 4.2
(i) Name the type of reaction.
........................................................................................................................................ [1]
(ii) Identify D and the conditions used.
........................................................................................................................................ [1]
(e) (i) Both $\sigma$ and $\pi$ bonds are present in a molecule of E as a result of different types of hybridisation in the carbon atoms.
Complete Table 4.2 to show the number of carbon atoms with each type of hybridisation in a molecule of E.
[Table 4.2]
+--------------------------+
| number of carbon atoms |
| sp hybridised |
| sp^2 hybridised |
| sp^3 hybridised |
+--------------------------+
| E |
+--------------------------+
[2]
(ii) Describe the essential feature of an unbranched hydrocarbon that causes its molecules to show stereoisomerism. Explain how this feature leads to stereoisomerism.
........................................................................................................................................
........................................................................................................................................
........................................................................................................................................ [3]
577
547
562
Compound $W$ has molecular formula $C_4H_{10}O$. It contains only one functional group.
(a) Table 5.1 shows the two peaks with the greatest $m/e$ values in the mass spectrum of $W$.
\[ \text{Table 5.1} \]
| $m/e$ | relative abundance |
|---|---|
| 74 | 50 |
| 75 | x |
(i) Calculate the relative abundance, $x$, of the peak at $m/e = 75$ using the information from Table 5.1.
$x = \text{...............................}$ [1]
(ii) The mass spectrum of $W$ also shows peaks at $m/e = 29$ and $m/e = 59$.
Suggest the molecular formulae of these fragments.
$m/e = 29 \text{...............................}$
$m/e = 59 \text{...............................}$ [2]
(b) A sample of $W$, $C_4H_{10}O$, is heated under reflux with an excess of acidified $K_2Cr_2O_7$ until there is no further reaction. Only one organic product, $X$, is present in the mixture at the end of the reaction.
Fig. 5.1 shows the infrared spectrum of $W$.
Fig. 5.2 shows the infrared spectrum of $X$.
$\text{Table 5.2}$
| bond | functional groups containing the bond | characteristic infrared absorption range (in wavenumbers)/cm-1 |
|---|---|---|
| C–O | hydroxy, ester | 1040–1300 |
| C=C | aromatic compound, alkene | 1500–1680 |
| C=O | amide, carbonyl, carboxyl, ester | 1640–1690, 1670–1740, 1710–1750 |
| C≡N | nitrile | 2200–2250 |
| C–H | alkane | 2850–2950 |
| N–H | amine, amide | 3300–3500 |
| O–H | carboxyl, hydroxy | 2500–3000, 3200–3650 |
(i) Absorption $A$ is shown in Fig. 5.1.
Absorption $B$ is shown in Fig. 5.2.
Complete Table 5.3 using the information given in Fig. 5.1, Fig. 5.2 and Table 5.2.
\[ \text{Table 5.3} \]
| absorption | bond | functional group containing the bond |
|---|---|---|
| A | ||
| B |
(ii) Use the information in (a) and (b)(i) to draw the structure of $X$ in the box in Fig. 5.3.
(c) $Y$ is a structural isomer of $W$.
Both $W$ and $Y$ produce colourless bubbles when sodium is added to them.
$Y$ does not react when heated with acidified $K_2Cr_2O_7$.
$Y$ does not react when warmed with alkaline $I_2(aq)$.
(i) Name the functional group present in $Y$.
.......................................................................................... [1]
(ii) Complete the equation to describe the reaction of $W$ or $Y$ with sodium.
..........$C_4H_{10}O$ + ..........$Na \rightarrow$ ................................................................... [1]
(iii) Draw the structure of $Y$. [1]
599
501
552
