Since the unkown acid is monoprotic, this also equals the number of moles of acid to use. A typical molar mass for an unknown acid in this experiment is 380 g/mol. Using this molar mass, calculate the mass (in grams) of unknown acid you should use per titration.
1.Suppose that 10.2 mL of 0.0512 M NaOH were required to titrate a sample of unkown acid. How many moles of NaOH were used? The answer i got is 0.00052224
2. Assuming that the unknown acid sample in question 1 had a mass of 0.177g, what is the molar mass of the unknown acid?
I tried everything and cant figure out number 2.
3 answers
You leave us in the dark with this. Instead of saying you tried everything, post what you tried and let us find the error. This we're playing guessing games.
I tried:
0.00052224=0.1777/x
0.00052224=380/x
0.00052224=0.1777/x
0.00052224=380/x
0.177, not 0.1777. Then
0.000522 = 0.177/x
x = 0.177/0.000522 = 338.9 which rounds to 339.
Your line three doesn't follow from line 2. Line 2, except for the extra 7 in the grams is ok. I don't know where the 380 came from. If you had finished and shown how you obtained x I might be more definitive. Sometimes these data bases count the answer incorrect if you use too many significant figures. You are allowed only 3 places. You never actually solved for x so I can't tell where you made the error.
0.000522 = 0.177/x
x = 0.177/0.000522 = 338.9 which rounds to 339.
Your line three doesn't follow from line 2. Line 2, except for the extra 7 in the grams is ok. I don't know where the 380 came from. If you had finished and shown how you obtained x I might be more definitive. Sometimes these data bases count the answer incorrect if you use too many significant figures. You are allowed only 3 places. You never actually solved for x so I can't tell where you made the error.
1 answer