I'm doing an experiment and I'm supposed to have neutral basic and acid samples of solution.

I just wanted to make sure that I knew which was which. (If I'm incorrect, please correct me)

Acid: 0.7ml 10% H2SO4 + 0.7ml 10% Na2WO4(sodium tungstate)

Basic: 0.7ml NaOH + saturated HgCl2

Neutral: 0.7ml saturated K2CO3

Thank you.

Responses

science(chem) - DrBob222, Saturday, September 20, 2008 at 10:42am
I would expect the first one to be acid, the second to be basic and the third to be basic. K2CO3 is the salt of a strong base (KOH) and a weak acid (H2CO3) so it will hydrolyze to produce OH^- and that should make it basic. NaCl or KCl solutions will be neutral.

The last one was what was confusing me. The manual I'm using says that one should be acidic, basic, and neutral.

I don't know how this would work.
I was told in the manual that I would have one of each.

I do add ethanol to each as well (later) Would this affect the basisity/acidity thus making the last, neutral?

Thank you,
Dr.Bob

K2CO3 is practically insoluble in alcohol. I looked in The Merck Index and it shows K2CO3 solution to be strongly alkaline (as the book puts it) with a pH about 11.6. I think the H2SO4/Na2WO4 might be somewhat of a buffer since H2SO4 has a k2 and tungstate ion will hydrolyze BUT with k1 being completely ionized I would not expect it to be neutral (perhaps just not as acid as one might expect with straight H2SO4). If I knew one of the three had to be neutral, I would pick on the second one in your list. My experience with NaOH and Hg^+2 is the formation of a ppt and if the Hg ppts that would leave a solid, practically insoluble, with NaCl. I think that comes the closest to being neutral of the three. I initially didn't pick this one because you didn't say anything about a ppt and I thought I just didn't remember. You know how we get with old age. But I looked it up tonight and I'm correct about the ppt.

Okay, thanks Dr.Bob.

To determine whether a solution is acidic, basic, or neutral, you need to consider the substances present in each solution and their properties.

In the first solution, you have 0.7ml of 10% H2SO4 (sulfuric acid) and 0.7ml of 10% Na2WO4 (sodium tungstate). Both sulfuric acid and sodium tungstate are acidic substances, so it is safe to say that this solution is acidic.

In the second solution, you have 0.7ml of NaOH (sodium hydroxide) and saturated HgCl2 (mercury(II) chloride). Sodium hydroxide is a strong base, so this solution is basic. However, the presence of saturated HgCl2 could potentially react with NaOH and affect the basicity of the solution. This would depend on the concentration and reaction between the two substances.

In the third solution, you have 0.7ml of saturated K2CO3 (potassium carbonate). K2CO3 is a salt of a strong base (KOH) and a weak acid (H2CO3). When dissolved in water, the salt will hydrolyze and produce OH- ions, making this solution basic.

Adding ethanol to each solution later may not significantly affect the acidity or basicity of the solutions, as ethanol is a neutral substance. However, it is always recommended to perform controlled experiments to confirm the effects of any added substances.

Regarding the confusion in the manual stating that one solution should be acidic, one basic, and one neutral, it is possible that there is a mistake or other factors not accounted for in the explanation. It would be best to consult with your instructor or refer to additional resources to clarify this discrepancy.