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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Woopy on July 19, 2012, 03:20:29 AM

Title: % of Na2CO3 in an unknown sample
Post by: Woopy on July 19, 2012, 03:20:29 AM

A student titrated 25 ml HCL with 24.79 ml NaOH. When 0.4872 g KHP was titrated with NaOH, 25.31 ml NaOH was used. A Na2CO3 solution was made using 1.8746g of unknown Na2CO3 sample in a total volume of 100 ml of solution. Then 10 mL Na2CO3 was titrated with 10.93 ml of HCL solution. What is the % Na2CO3 in the student's unknown?

I don't even know where to begin with this guy. We are doing a lab on it tommorow, and its like a 3 step titration before you can even start calculating the mass of the Na2CO3 present in the unknown sample. What do I do?

Title: Re: % of Na2CO3 in an unknown sample
Post by: sjb on July 19, 2012, 04:31:41 AM

Quote from: Woopy on July 19, 2012, 03:20:29 AM

A student titrated 25 ml HCl with 24.79 ml NaOH. When 0.4872 g KHP was titrated with NaOH, 25.31 ml NaOH was used. A Na₂CO₃ solution was made using 1.8746g of unknown Na₂CO₃ sample in a total volume of 100 ml of solution. Then 10 mL Na2CO3 was titrated with 10.93 ml of HCl solution. What is the % Na₂CO₃ in the student's unknown?

I don't even know where to begin with this guy. We are doing a lab on it tommorow, and its like a 3 step titration before you can even start calculating the mass of the Na₂CO₃ present in the unknown sample. What do I do?

Start by writing equations for each of the titrations?


Sometimes problems are multistep, you can't just go from A direct to Z, but have to work via B, C, etc.