(a) Write an equation in each case to represent the (i) \(\beta\)-decay of \(^{24}_{11}Na\) to give Mg.
ii) reaction of sodium with cold water.
b)(i) State two differences between reaction (a)(i) and (ii)
ii) State two applications of the type of reaction represented in(a)(i)
(c) Consider the reaction represented by the equation:
Mg\(_{(s)}\) + 2HCI\(_{(aq)}\) \(\to\) MgCl\(_{(aq)}\) + H\(_{(q)}\)
(i) Name the type of reaction involved
(ii) Give two ways by which the reaction could be made faster.
(iii) What volume of hydrogen gas would be produced from 6.0 g of the magnesium? [ H = 1; 1 mole of gas occupy 22.4 dm\(^3\) at s.t.p. ]
(d) What is (i) an electrolyte?; (ii) electrolysis?
(e)(i) Give one metal that is extracted using electrolytic process.
(ii) Name the ore of the metal.
(iii) What is the substance discharged at each electrode when dilute NaCI is electrolysed using graphite electrodes?
(iv) Why would aqueous NaCI conduct electricity but solid NaCI would not?
(v) Give one industrial use of NaCI.
Explanation
(a) (i)
\(^{24}_{11}Na\) \(\to\) \(^{24}_{12}Mg\) + \(_1\beta\)
(ii) 2Na\(_{(s)}\) + 2H\(_2\)O\(_{(l)}\) \(\to\) 2NaOH\(_{(aq)}\) + H\(_{2(g)}\)
(b)
|
Reaction (i) |
Reaction(i) |
|
Takes place in the nucleus or nucleus reaction |
Takes place in the valence shell or chemical reaction |
|
Large amount of heat is released |
Small amount of heat is released |
|
Involves proton, neutrons and electrons. |
Involves valence electrons |
|
New nuclides are formed |
Newxompounds are formed |
|
Not affected by external factors e.g temperature, pressure, catalyst. |
Usually affected by external factors. |
(ii) Sterilizing instruments
-- treatment of cancer
- carbon dating
- pest control, etc.
(c)(i) Displacement reaction.
(ii) using Mg powder i.e increasing the surface area of Mg.
- using higher concentration of HCI
- increase temperature of the reaction mixture.
(iii) 24g Mg = 22.4 dm\(^3\) of H\(_2\) gas
6g Mg = \(\frac{6g \times 22.4 dm^3}{24g}\)
= 5.6 dm\(^3\).
(d)(i) An electrolyte is a compound which when molten or in aqueous solution will conduct electricity.
(ii) Electrolysis is the decomposition of an electrolyte by the passage of an electric current.
(e)(i) Aluminium
(ii) Bauxite
(iii) Cathode
- Hydrogen Anoda
- Oxygen
(iv) In the liquid state the Na+ and CI\(^-\) ions are mobile while in the solid state the ions ere in fixed position and cannot conduct electricity.
(v) Industrial uses of NaCI In the manufacture of CI\(_{2(g)}\)
— Salting out in soap manufacture
— Production of NaOH
— Solvay process