Question

1. Recall the 0.1 M NaOH you just titrated was made from 1 M NaOH (“mother solution”). If the new accurate concentration determined by titration today is 0.111 M, what is the actual concentration of the “mother solution”?

Hint: Pay attention to significant figures

A. 1.00 M
B. 1.11 M
C. 0.909 M
D. 1.111 M

If it is saying to pay attention to significant figures would that mean the 0.111 that the answer would be B. 1.11?

2. If Ma and Va represent the molarity and volume for the analyte, and Mt and Vt represent the molarity and volume for the titrant, for a monoprotic acid-base pair, we can use the equation: Ma Va = Mt Vt

A) True

B) False

I think this is false because isn' t the equation usually Ma Va = Mb Vb?

Answer 1

1)
0.1 --> 1 significant
1 --> 1 significant
0.111 --> 3 significants

M1 x V1 = M2 x V2
1 x V1 = 0.1 x nV1
1 = 0.1 x n
n= 10

V2 = 10 x V1

M1 x V1 = M2 x V2
M1 x V1 = 0.111 x 10V1
M1 = 1.11 M (3 significants)
M1 = 1 M (1 significant)

2) I think this one is true,
since titration equation is :
M1 x V1 x n1 = M2 x V2 x n2

because the question said it's monoprotic acid based, then the coefficent should be one :
M1 x V1 x 1 = M2 x V2 x 1

We can simplify it to:
M1 x V1 = M2 x V2

For Ma x Va = Mt x Vt -->
Ma stands for unknown concentration (analyte) Mt stands for known concentration (titrant)

Anyway what is Ma, Va, Mb, Vb stands for?