[Edbag]

Hey all, I've been in a skype call for hours with my friends trying to figure this stuff out. It's a question about percentage by mass of Chloride in brick cleaner. Let me give you the prior information. 0.010L of brick cleaner is made into a solution of 0.250L by adding 0.240L deionized-water. The concentration of undiluted brick cleaner is found to be 4.95M, and the concentration of diluted brick cleaner 0.198M.
Silver nitrate is added in excess to a 0.010L aliquot of the diluted brick cleaner solution. A dried precipitate is collected, with a mass of 0.8g. The % composition of Chloride in Silver Chloride is found to be 24.8% The mass of Chloride in the precipitate was then found to be 0.1984g.
Ok now I've done everything, but I need help calculating the percentage, by mass of Chloride in the undiluted brick cleaner, and then consequently the percentage by mass of HCl in the diluted brick cleaner.
The last part asks me to compare my result from doing volumetric analysis, which was: "The concentration of undiluted brick cleaner is found to be 4.95M", and my result from finding the percentage by mass of HCl obtained from gravimetric analysis. How can I compare these?

PS. I'm aware of the "we won't do your hw for you" rule, but i've done like 95% of the entire booklet assignment myself, and me and all my friends are seriously stuck on this. If you can help, I'll love you forever. Please let me know if you realise I left any information out.

[Borek]

Either the question itself is ambiguous, or your description is.

The concentration of undiluted brick cleaner is found to be 4.95M

4.95M - of what?

The mass of Chloride in the precipitate was then found to be 0.1984g.

Mass of chloride in precipitate, or mass of precipitate?

Ok now I've done everything, but I need help calculating the percentage, by mass of Chloride in the undiluted brick cleaner, and then consequently the percentage by mass of HCl in the diluted brick cleaner.

IMHO you can't calculate neither - you don't know the density of the original solution. Assuming it was just that of water (1 g/mL) means introducing 8% error (density of 5M hydrochloric acid is 1.08 g/mL).