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Question

A titration is done using 0.10 M NaOH in the buret and 15.0 mL of 0.18 M HCl in the Erlenmeyer Flask. How many moles of HCl are left in the flask after a total of 5.0 mL of the 0.10 M NaOH solution were added to the flask?

Answer 1

Hello Liz

 

NaOH  +  HCl  -->  NaCl  +  H₂O

 

From this reaction, we can see that NaOH and HCl react in a 1:1 mole ratio.

 

First, calculate the # of moles NaOH added using the volume, 5.0 mL, and the molarity, 0.10 M.

 

mol NaOH  =  0.10 M  x  0.0050 L  =  0.00050 mol NaOH

 

Second, calculate the # of moles of HCl present in the Erlenmeyer flask.

 

mol HCl  =  0.18 M  x  0.0150 L  =  0.0027 mol HCl

 

From the titration, 0.00050 mol NaOH will neutralize 0.00050 mol of HCl since they react in a 1:1 mole ratio.  Therefore, the # of moles of HCl remaining is:

 

mol HCl remaining  =  0.0027  -  0.00050  =  0.0022 mol HCl