Identify the precipitate (if any) that forms when Na2S and CdSO4 are mixed Solut
ID: 622034 • Letter: I
Question
Identify the precipitate (if any) that forms when Na2S and CdSO4 are mixedExplanation / Answer
a) Sn(NO3)2 (aq) + 2 NaOH (aq) ---> Sn(OH)2 (s)+ 2 NaNO3 (aq) b) 2 NaOH (aq) + K2SO4 (aq) --> Na2SO4 (s) + 2 KOH (aq) c) Na2S (aq)+ Cu(C2H3O2)2 (aq)--> CuS(s) + 2 NaC2H3O2 (aq) The ones with (s) are the precipitates (solid) (aq) = aqueous solution --------------------------- A precipitate is a compound that is insoluble in water. For example, in the first one: Sn(NO3)2 (aq) + 2 NaOH (aq) ---> Sn(OH)2 (s)+ 2 NaNO3 (aq) Sn(OH)2 is NOT soluble in water. Moreover, Sodium (Na) is way more reactive than tin. The same happen with the rest of the reactions. Bottom lime: If any of these products is insoluble, then it will be the precipitate. Another example: Al2(SO4)3 (aq) + 3CaCl2 (aq) => 2AlCl3 (aq) + 3CaSO4 (aq) A precipitate will form, and it is CaSO4. As a rule, anything with: Na+, K+, Cl- NO3- are soluble. Those without are not, with a few exceptions that are slightly soluble such as lead sulfate (from memory), and AgCl which, although contains chloride, is not soluble.