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don't know if the pH problem is solved, but I cba checking pages and he should've updated the questions.

pH = -log[H+]
1.2 = -log[H+]
-1.2 = log [H+]
10^(-1.2) = 0.063

Thus the concentration of the strong acid is 0.063M.


Mass problem.

50% NaOH => 500g NaOH in a 1L solution.
But you don't know the density of the solution, thus you don't know the weight of the solution.
Density of pure water isn't the same as the density of a solution.
Thus afaik, you can't solve the problem due to lack of information.

Let's say the density is 1kg/l (not true, but it's an assumption)

Thus you'd have 500g/40g/mol = 12.5M.


Are you sure that the answer is 19M?
If yes

19M*40 = 760g of NaOH.
Density would be 1520g/l (missing value you need).


I <3 chem.


[edit]I googled the density and it's 1.53kg/l

Thus 1 litre = 1530 grams.
=> 765g of NaOH.
=> 765g/40g/mol = 19.125M

19.125M solution

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