Acid-Base Titration Example calculation to try In an experiment, 20.00 mL of an

Question

Acid-Base Titration Example calculation to try In an experiment, 20.00 mL of an HCl solution with of an HCl solution with an unknown concentration was titrated with a 0.0980 M NaOH solution: Ha(aq) + NaOH(m) Naa(aq) + H,0 point appeared when 22.45 ml, of the NaOH solution was added to the HCI solution, which works out to the following number of moles of NaOH: ni-(0.0980 (0 02245 L) -2.20 x 10-3 mol NaOH where R number of moles of NaOH added to reach the equivalence point (mol) v, = volume of NaOH added to reach the equivalence point (L) e concentration of the NaOH standard (mol/L) Since HCl and NaOH react in a 1:1 stoichiometric ratio, the number of moles of HCl in the sample with unknown concentration must be the same. Knowing the number of moles, the concentration of the hydrochloric acid solution can be calculated: 2.20 x 10 mol HCI) (0.02000 L 0.110 M where n1 number of moles of NaOH added to reach the equivalence point (mol) n2 number of moles of HCl in the sample solution (mol) vi-volume of the HCl sample (L) c2 concentration of the HCl solution (mol/L) Therefore, the concentration of the unknown HCl solution is 0.1100 M. 1. Does it matter what the volume is of the unknown solution you choose to titrate? 2. Assuming an experiment is performed using a 50-mL buret filled to the zero mark with a standardized 0.10 M NaOH solution, and t he approximate concentration of the 2 PS-28978

Explanation / Answer

1. for sure it will matter as no. of moles of reactant will increase with volume

for example lets have 1M solution

1L will have = 1M x 1L = 1 moles reactant

2 L will have = 1M x 2L = 2 moles reactant

In first case the titrant will have to react with 1 moles reactant

and in second case titrant will have to react with 2 moles reactant

2.

Approximate concentration of unknown can be obtained using the reaction equation

HCl + NaOH -----> NaCl + H2O

If volume of HCl is taken as VHCl ,which you will measure in lab

VNaOH = volume of NaOH used to titrate completly(obtained from burate readings)

M1V1 = M2V2

MHCl x VHCl = 0.10M x VNaOH

MHCl = 0.10M x VNaOH / VHCl

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