posted by Kate on .
What is the concentration of a solution prepared by diluting 25.0 mL of HCl 0.750 mol/L to a final volume of 500. mL?
molarity = mols/L.
mols HCl = M x L
mols HCl = 0.750 M x 0.025 L = ??
Now M = mols/L= ??/0.500
mols HCl = 0.750 M x 0.025 L = 0.0186 mol
M = 0.0186 mol/0.500 L = 0.0372
the answer is 0.0372 mol/l
I don't know what you teacher prefers but I would not round the 0.750 x 0.0250 = 0.01875. Just leave that in the calculator and divide that number (whatever is in the calculator) by 0.500 and the answer is 0.0375. You are allowed three significant figures. Doing it as you did gives rounding errors. You can see what difference it makes.
Thank you, I made the change. My professor is very precise, so I'm glad you noticed that!