Answer:
Explanation:
Determine the number of moles of sodium thiosulfate that are equivalent to one mole of sodium
hypochlorite.
2 S2O3
2− = I−
3 = I2 = ClO−, therefore, for every mole of sodium thiosulfate, we need one half of a
mole of sodium hypochlorite.
2. Calculate the average volume of Na2S2O3
to determine the molarity of the diluted bleach.
16.8 + 17.6
2
= 17.2
3. Use the average volume and molarity of Na2S2O3
to determine the molarity of the diluted bleach.
mol Na2S2O3 = (0.0172)(0.1) = 0.00172
⇓
(0.00172)
2
= 0.000852 mol NaClO
⇓
0.000852
0.025
= 0.341 M NaClO
4. Calculate the average molarity of the commercial bleach before it was diluted.
0.000852 × 4 = 0.0034
0.0034
0.005
= 0.68 M NaClO
5. Assume the density of the commercial bleach is 1.08 g/mL. Calculate the average percent by mass of
NaClO in the commercial bleach.
0.0034 × 74.4424 = 0.2536 g
5mL × 1.08 g/mL = 5.4g
0.2536
5.4 = 4.70%
6. From the label information of the commercial bleach calculate the average deviation of the three
titration values.
|0.047 − 0.060| = 0.013
7. Calculate the percent error of your value.
