Chemistry Past Questions and Answers

The oxidation number of iodine in the iodate ion (IO <sup style='font-size: smaller;'>-</sup><sub style='font-size: smaller;'>3</sub>) is

Metals can be extracted from their ores by a process involving

Consider the reaction: 2AI<sub style='font-size: smaller;'>(s)</sub> + 6H<sup style='font-size: smaller;'>+</sup><sub style='font-size: smaller;'>(aq)</sub> → 2AI<sup style='font-size: smaller;'>3+</sup><sub style='font-size: smaller;'>(aq)</sub> + 3H<sub style='font-size: smaller;'>2(g)</sub>. What is the total number of moles of electrons transferred from the aluminium atoms to the hydrogen ions?

In the reaction represented by the equation. 5Fe <sup style='font-size: smaller;'>2+</sup><sub style='font-size: smaller;'>(aq)</sub> + MnO<sup style='font-size: smaller;'>-</sup><sub style='font-size: smaller;'>4(aq)</sub> + 8H<sup style='font-size: smaller;'>+</sup><sub style='font-size: smaller;'>(aq)</sub> → 5Fe<sup style='font-size: smaller;'>3+</sup><sub style='font-size: smaller;'>(aq)</sub> + Mn<sup style='font-size: smaller;'>2+<sub style='font-size: smaller;'>(aq)</sub> + 4H<sub style='font-size: smaller;'>2</sub>O<sub style='font-size: smaller;'>(l)</sub> which species is reduced?<br/></sup>

Which of the following industrial processes is chlorines not used?