A5.00-ml sample of an h3po4 solution of unknown concentration is titrated with a 0.1090 m naoh solu- tion. a volume of 7.12 ml of the naoh solution was required to reach the equivalence point. what is the concentration of the unknown h3po4 solution?

The concentration  of  unknown  H3PO4  solution is 0.052 M

calculation

step 1:  write  the   balanced molecular equation

3NaOH +  H3PO4→  Na3PO4  +3H2O

step 2: find the  moles of NaOH

moles =  molarity x volume  in liters

volume  in liters = 7.12  ml  /1000 =  0.00712  L

molarity =  0.1090 M =  0.1090  mol/l

moles is therefore = 0.1090  mol/L  x   0.00712  L =0.00078  moles

step 3:  use the  mole  ratio to determine the moles of H3PO4

H3Po4: NaOH  is  3:1 therefore the  moles  of H3PO4

=  0.00078  x1/3 =0.00026 moles

Step 4:  calculate the   molarity   of H3PO4

molarity =  moles/volume in liters

volume in liters = 5.00 / 1000 =0.005  L

molarity is= 0.00026/0.005=0.052 M

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