To measure the amount of nickel in some industrial waste fluid, an analytical chemist adds 0.110 M sodium hydroxide (NaOH) solution to a 25.0 g sample of the fluid and collects the solid nickel(I) hydroxide (Ni (OH2) product. When no more Ni(OH)2 is produced, he filters, washes and weighs it, and finds that 343. mg has been produced The balanced chemical equation for the reaction is: Ni2+(aq) + 2NaOH(aq) Ni(OH)2(s) + 2 Na. What kind of reaction is this?
a. precipitation
b. acid-base
c. redox

a. precipitation

Explanation:

In the reaction:

Ni²⁺(aq) + 2NaOH(aq)→ Ni(OH)₂(s) + 2 Na⁺

Nickel is precipitated as Ni(OH)₂ producing Na⁺ ions.

In a precipitation two soluble ions react with each other to produce an insoluble salt.

In our problem, Ni²⁺ is reacting with OH⁻ to produce Ni(OH)₂, an insoluble salt

The reaction is a precipitation

In an acid-base reaction, an acid reacts with a base to produce water and a salt. In this problem is a base reacting (NaOH) but there are no acids in the reaction.

And in a redox reaction an ion is been oxidized whereas the other is been reduced (Loosing electrons and gaining electrons).

As you can see, Ni²⁺ still with oxidation number of 2+ in Ni(OH)₂ and Na⁺ is always +1-. Thus, this is not a redox reaction.

by cartels in other countries, shipped by air, mail, or land. i cant really see your answer choices : /

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.