Composition of a Mixture by Acid-Base Titration

[veena]

A 1.00-g solid sample containing a mixture of table salt (NaCl) and citric acid (H3C6H5O7, a triprotic acid) is dissolved in 15 mL of water.
Titration of the acid solution requires 40.00 mL of 0.2003 M NaOH solution to reach the endpoint.
Calculate the mass percent H3C6H5O7 in the solid mixture.

Can somone please explain how to do this problem...??

 

[chemisttree]

Start by writing out the neutralization equation.

 

[veena]

I have tried but i don't know how to solve for M2

M1 x V1 = M2 x V2

can u help please

 

[chemisttree]

Start by writing out the neutralization equation.

 

[AbedeuS]

First, figure out how many moles of NaOH were used, this will be equivalent to the amount of OH^{-} in the titration mixture, if its the end point OH^{-} = H^{+}, I hope that gets you closer to your final goal, as its bad policy for us to just give you a full answer.

Or, just do what chem said, write the neutralization equation (I do the more manual way personally ¬_¬ )

 

[symbolipoint]

A 1.00-g solid sample containing a mixture of table salt (NaCl) and citric acid (H3C6H5O7, a triprotic acid) is dissolved in 15 mL of water.
Titration of the acid solution requires 40.00 mL of 0.2003 M NaOH solution to reach the endpoint.
Calculate the mass percent H3C6H5O7 in the solid mixture.

Can somone please explain how to do this problem...??

"triprotic acid"... Which endpoint? Is your course "elementary chemistry" or is it undergraduate "Quantitative Chemistry"?

 

[AbedeuS]

I think he will be reffering to the third endpoint, rather than the first.