A student obtained the following results from Part 2B of the lab: X = precipitat

ID: 849719 • Letter: A

Question

A student obtained the following results from Part 2B of the lab:

X = precipitate form ; NP = no precipitate form

Did the student conduct the experiment correctly?

Yes, the student performed the experiment correctly.

No, the student mistakenly added Cu(NO3)2 solution instead of the Mg(NO3)2 solution.

No, the student mistakenly added AgNO3 solution instead of the Mg(NO3)2 solution.

No, the student mistakenly added Fe(NO3)3 solution instead of the Mg(NO3)2 solution.

No, the student mistakenly added NaOH solution instead of the Mg(NO3)2 solution.

Mg(NO3)2 NaCl NP Na2S NP NaOH NP Na2CO3 NP

The table shows that no ppt with any of the reagents however

(i) MgNO3 forms ppt with NaOH,

Mg(NO3)2(aq)+2NaOH(aq)--> Mg((OH)2 (s) + 2 NaNO3 (aq)

(ii) MgNO3 forms ppt with Na2S

Mg(NO3)2(aq)+Na2S(aq)--> MgS (s) + 2 NaNO3 (aq)

so answer is: the student did not conduct the experiment correctly

(i) It could not be Ca(NO3), as it forms ppt with Na2CO3

(ii) It could not be AgNO3 as it forms ppt with NaCl etc

(iii) It could not be Fe(NO3)3 as it forms ppt with Na2S , Na2CO3 and NaOH

(iv) So correct answer is : No, the student mistakenly added NaOH solution instead of the Mg(NO3)2 solution.

Mg(NO3)2 NaCl NP Na2S NP NaOH NP Na2CO3 NP

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