Question

“Ogre’s Ocean” water (OOH for short) was tested in a similar manner to the procedure given in experiment 1 in UFV’s Chem 114 lab manual. However, in this case, 50.00 mL of OOH was diluted to 250.0 mL with deionized water. In the determination of the total cation concentration, 25.00 mL aliquots of the dilute OOH were passed through a cation exchange column and the eluent titrated with an average 27.42 mL of 0.1134M NaOH. In the determination of calcium and magnesium cations, 25.00 mL aliquots of the dilute OOH were titrated with an average 34.03 mL of 0.01018M EDTA.

*Take note that the ratio of magnesium to calcium cations in OOH is 3:2 and the dilution and ratio used are both different from what is stated in the lab manual.

How many moles of NaOH were used to titrate the eluent of the 25.00 mL dilute OOH?

Answer 1

Q. How many moles of NaOH were used to titrate the eluent of the 25.00 mL dilute OOH?

we have, eluent titrated with an average : 27.42 mL of 0.1134M NaOH

Molarity of NaOH : 0.1134 M

Volume of NaOH solution used : 27.42 mL

Thus, moles of NaOH were used to titrate the eluent of the 25.00 mL dilute OOH :

   0.1134 mol/L * ( 27.42 mL / 1000 mL/L )   = 3.109*10^-3 moles .