Calculate the amount of NaOH in this solution
5.00mL of 12.0 NaOH is diluted with water to make 24 mL of 2.50 NaOH solution
Ignore the 24 mL and 2.50 M. What you have is what you originally put in. That is 5.00mL x 12.0 M (you didn't put units but I'm guessing M). So mols = M x L and grams = mols x molar mass or about 2.4 grams of NaOH.
To calculate the amount of NaOH in the solution, you can use the concept of concentration.
First, let's find the initial concentration of the 5.00 mL of 12.0 M NaOH solution:
Concentration1 * Volume1 = Concentration2 * Volume2
(12.0 M) * (5.00 mL) = Concentration2 * (24 mL)
Concentration2 = (12.0 M * 5.00 mL) / 24 mL
Concentration2 = 2.50 M
So, the concentration of the 5.00 mL of 12.0 M NaOH solution after dilution is 2.50 M.
Now, let's calculate the amount of NaOH in the 24 mL of 2.50 M NaOH solution:
Amount = Concentration * Volume
Amount = (2.50 M) * (24 mL)
Amount = 60.0 millimoles (mmol)
Therefore, the amount of NaOH in the solution is 60.0 millimoles (or 60 mmol).