State why lanthanum cannot be produced by reducing its oxide with carbon.

Calculate the current (I), in A, required to produce 1.00 kg of lanthanum metal per hour. Use the formula \(Q(C) = I(A) \times t(s)\) and sections 2 and 6 of the data booklet.

too high/higher than carbon in the reactivity series
OR
carbon/C is a weaker reducing agent than lanthanum/La

Accept “lanthanum is more reactive than carbon”.

Accept “lanthanum is a weaker oxidizing agent than carbon”.

Accept converse arguments.

[1 mark]

amount of La «\( = \frac{{1000{\text{ g}}}}{{138.91{\text{ g}}\,{\text{mo}}{{\text{l}}^{ - 1}}}}\)» = 7.20 «mol»

Q «= 7.20 mol x 3 x 96\(\,\)500 C\(\,\)mol^–1» = 2.08 x 10⁶ «C»

I «\(\frac{{2.08 \times {{10}^6}{\text{ C}}}}{{60 \times 60{\text{ s}}}}\)» = 579 «A»

Award [3] for “578 «A»” (from premature rounding) or “579 «A»”.

[3 marks]