Chemistry

5013 s and p – Block ElementsLead (II) chloride is fairly insoluble in water and, instead of getting a solution, it would forman insoluble layer over the lead (II) oxide if you were to use dilute hydrochloric acid - stoppingthe reaction from going on.However, in this example we are talking about using concentrated hydrochloric acid.The large excess of chloride ions in the concentrated acid react with the lead(II) chloride toproduce soluble complexes such as PbCl4 2- . These ionic complexes are soluble in water and sothe problem disappears.The Acidic Nature of the OxidesAll of these oxides also react with bases like sodium hydroxide solution.Lead(II) oxide, for example, would react to give PbO2 2- - plumbate(II) ions.The DioxidesThese dioxides are again amphoteric - showing both basic and acidic properties.The Basic Nature of the DioxidesThe dioxides react with concentrated hydrochloric acid first to give compounds of the typeXCl4:These will react with excess chloride ions in the hydrochloric acid to give complexes suchas XCl6 2- .In the case of lead(IV) oxide, the reaction has to be done with ice-cold hydrochloric acid. Ifthe reaction is done any warmer, the lead(IV) chloride decomposes to give lead(II) chloride andchlorine gas. This is an effect of the preferred oxidation state of lead being +2 rather than +4.The Acidic Nature of the DioxidesThe dioxides will react with hot concentrated sodium hydroxide solution to give solublecomplexes of the form [X(OH)6] 2- .Some sources suggest that the lead(IV) oxide needs molten sodium hydroxide. In thatcase, the equation is different.