Question

1. In Part 1 Synthesis Reactions, the product of the first reaction is Al(OH)3. The product of the second reaction is Mg(OH)2. Describe what you observed in each reaction. Next, consider the general AB form of a synthesis reaction. If the first set of reactants is NH4OH and KAl(SO4)2 and the second set of reactants is MgSO4 and NH4OH, is either reaction considered a synthesis reaction as labeled in the laboratory? Why or why not? Note: Mg(OH)2 and Al(OH)3 are both used commercially as antacids.

Answer 1

Answer. None of the reactions asked in the question are considered as synthesis reaction.

Explanation  According to definition of synthesis reaction two of the reactants react together in order to form a single product . synthesis reaction are also known as combination reactions.

                                              $A+B\rightarrow AB$............(1)

  where 'A' and 'B' are the reactants where 'AB' represent the product after reaction.

In part one, the reaction in which ammonium hydroxide reacts with potassium aluminium sulfate not only to give aluminium hydroxide  but also gives ammonium sulfate , potassium hydroxide and water.

$NH_{4}OH+KAl(SO_{4})_{2}\rightarrow Al(OH)_{3} +(NH_{4})_{2} SO_{4} +KOH$  ....(2)

In part two,magnesium sulfate reacts with ammonium hydroxide to give not  only magnesium hydroxide  but also ammonium sulfate.

$MgSO_{4}+2NH_{4}OH}\rightarrow Mg(OH)_{2} +( NH_{4})_{2}SO_{4}$...(3)

as in both reaction there are more than one product which means they are not synthesis reactions.

Answer 2

The general form of a synthesis reaction is A + B --> AB. So we see two reactions here, NH4OH + KAl(SO4)2 --> Al(OH)3 (with some remaing K and NH4 and SO4), and MgSO4 + NH4OH --> Mg(OH)2 (with remaining SO4 and NNH4). Also, antacids is just a colloquial version of the word "base." So for the first reaction, we wouldn't call that a synthesis reaction, as this reaction would also include forming things like KOH. It doesn't follow the simple A+B-->AB. With the second one though, it would be more likely to see it written like Mg+2 + 2OH- --> Mg(OH)2, which does follow A+B--> AB, so it is a synthesis reaction.