Question 23 of 24 Incorrect Map Sapling Learning macmillan learning A solution c

Question

Question 23 of 24 Incorrect Map Sapling Learning macmillan learning A solution containing a mixture of metal cations was treated with dilute HCl and no precipitate formed. Next, H2S was bubbled through the acidic solution. A precipitate formed and was filtered off. Then, the pH was raised to about 8 and H2S was again bubbled through the solution. A precipitate again formed and was filtered off. Finally, the solution was treated with a sodium carbonate solution, which resulted in no precipitation. Which metal ions were definitely present, which were definitely absent, and which may or may not have been present in the orginal mixture? Definitely absent Possibly present Mg2+ Hg2+ Ag+ Sb3+

Explanation / Answer

i) There is no precipitate by adding dilute HCl, by this observation we can conclude first group cations are absent

So, Pb2+, Hg22+ and Ag+ are definitely absent

ii) Precipitation is formed by passing H2S through acidic solution,by this observation we can conclude second group cations are definetely present

So, Hg2+, Sb3+, Sn4+ and Cu2+ possibly present

iii) Precipitation is formed when H2S is passed through solution at pH 8, by this observation we can conclude fourth group cations are definitely present

So, Zn2+ and Ni2+ possibly present

iv) There is no precipitation by adding sodium carbonate, by this observation we can conclude fifth group cations are definitely absent

So, Ca2+ definitely absent

remaining cations are Al3+ (3rd group), K+(6thgroup) and Mg2+(6th group) are not underwent to their group test. So, these cations are may or may not present

Therefore,

we can conclude the following report

Cations definitely abasent : Hg22+, Pb2+, Ag+ and Ca2+

Cations possibly present : Cu2+, Sn4+, Hg2+, Sb3+, Zn2+ and Ni2+

Cations may or may not present : Mg2+, K+ and Al3+

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