chemistry
posted by anonymous on .
1) Starting with 75.00 g of 1propanol and 75.00 g of PCl 3. Calculate the theoretical yield of 1chloropropane.
3CH3CH2CH2OH + PCl 3 > 3CH3CH2CH2Cl + H3PO3 Answer in terms of grams.
the answer that i got is 98.12, is this right and how many sig figs should it be?
2) What is the concentration of a solution formed when 15.0 mL of 6.00 M HCl are diluted with 25.0 mL of water? Answer in terms of moles/L.
the answer that i got is 3.60, is this right and how many sig figs should it be?
3) What is the volume of a 3.72 M Na3PO4 solution needed to prepare 2.50 x 102 mL of a 1.43 M Na+ solution? Answer in terms of mL.
the answer that i got is 96.1, is this right and how many sig figs should it be?
4) What is the concentration of an HI solution if 75.0 mL of the acid required 35.21 mL of 0.1894 M KOH to reach the endpoint in the titration? Answer in terms of moles/L.
the answer that i got is 0.08892 is this right, and how many sig figs should it have?

I used 60.096 for the molar mass of the alcohol and 78 .54 for the molar mass of the 1chloropropane and I obtained 98.01817. You are allowed 4 s.f. so I would round my answer to 98.02 grams.
#2 is 3.60 and you are allowed 3 s.f.
#3. I don't think so.
You want moles Na = 1.43M x 0.250 = ?
moles Na3PO4 = moles Na/3 = ?
M Na3PO4 = moles Na3PO4/L Na3PO4 = about 32 mL. You are allowed 3 s.f.
#4 is ok. Are you having trouble with s.f.? Here is a link that should help.
http://www.chemteam.info/SigFigs/SigFigs.html 
are you sure about number 4? shouldn't it have 3 significant digits because of the 75.0 ml ?