Choose the option that has the pair of substances whose chemical reaction is eas
ID: 2124536 • Letter: C
Question
Choose the option that has the pair of substances whose chemical reaction is easily perceptiple a)Br2(aq) + NaCl(aq) b) Cl2(aq) + NaI(aq) c) H2(g) + MgSO4(aq) d) Ag(c) + ZnSO4(aq) e) HCl(aq) + Cu(c) I would say if the salt was an alkali salt, a would discolor the solution (Br2 is brown/red), as Br2 + H2O -> HBrO + HBr, and the equilibrum tends to form the products when the solution is basic. But the salt is NaCl, so nothing would happen The second one I would say no change would be noticed The third I would say some of the SO4-- could reduce to SO2 or some of the Mg++ to Mg, oxydating the H2 to H2O, but in a very low scale, so nothing would be noticed too For the third, as ZnSO4 forms a acid solution, I would say some of the silver would oxydate to Ag+, even silver being a noble metal. This will occur with a low velocity but I would say it could be noticed. For the last one, as Cu isn't a noble metal, I would say it will fastly oxidate to Cu2+, and the solution will color to blue, easily noticed I chose e as the answer, but by book is saying it is b. Why is that?Explanation / Answer
The reaction in b) will make sodium chloride and iodine. The iodine would give the solution a very dark brown colour that would be hard to miss. The answer isn't e) because that reaction doesn't happen. Copper is one of the few metal which are actually less reactive than hydrogen, so it can't replace it in the HCl.