show steps A sample of sodium carbonate (Na2C03), which is a base (assume the ti

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A sample of sodium carbonate (Na2C03), which is a base (assume the titration endpoint is reached when one proton has been transfered, producing NaHC03), with a mass of 0.2892 g is dissolved in water and used to standardize a solution of perchloric acid. An endpoint is reached when 32.03 mL of perchloric acid has been added. Determine the molarity (in mol/L) of the perchloric acid solution. Report your answer to four significant figures. The standardized perchloric acid solution is then used to titrate 41.10 mL of a solution of sodium lactate (NaC2H5OCOO). An endpoint is reached when 18.22 mL of perchloric acid has been added. Determine the molarity (in mol/L) of the sodium lactate solution. Report your answer to four significant figures.

Explanation / Answer

1)

Moles of Na2CO3 = mass /molecular mass ;

molecular mass = 2*23 + 12 + 16*3 = 106

moles = 0.2892/106

moles of perchloric acid = moles of Na2CO3 = 0.2892/106 ;

so molarity = moles / volume ;

volume = 32 mL = 0.032 L   

Molarity = 0.2892/(0.032*106) = 0.08526 M

2) M1*V1 = M2 *V2

0.08526*18.22 = M2*41.1

M2 = 0.0378 M

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