| MadSci Network: Chemistry |
Your question seems suitable for middle school students - the ambiguities
would only really apply at higher levels, but perhaps in can be re-
phrased in a more concrete form.
You mention that not enough information is given, well that would be
because it depends on both the strength and the concentrations of the two
solutions. Although I wouldn't expect middle school students to know
anything about moles (they will assume that the "equal proportions" refers
to volumes), they might have learnt about strong vs weak acids and bases,
and they should also have some idea of concentrated vs dilute.
Therefore I would phrase the question something like this:
"A solution of a strong acid has the same concentration as a solution of a strong base. If 25cm3 of the acid is combined with the same volume of the base, the pH of the resulting solution is:"Hope this is ok! You might also consider changing the answers. I doubt if middle school students have come across pH 0, and if you have a mildly acidic value, perhaps you should have a corresponding alkaline value. The "none of the above" is an obvious loser, so scrap it and have:
a) 1
b) 5
c) 7
d) 9
e)14
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