A 100.0 mL sample of natural water was titrated with NaOH. The titration required 14.53 mL of 0.1031 M NaOH solution to reach a light pink phenolphthalein end point. Calculate the number of millimoles of NaOH required for the titration.

The correct answer is 1.498.

Explanation:

Based on the given information, the volume of NaOH needed for the titration is 14.53 ml, and the concentration of NaOH given is 0.1031 M.

The volume of NaOH, that is, 14.53 ml can also be written as 14.53 × 10⁻³ L.

The concentration of NaOH, that is, 0.1031 M can also be written as 0.1031 moles/Litre.

Molarity (M) is determined as,

M = No of moles/Volume in litres

No of moles = Molarity × Litres

No of moles = 0.1031 moles/Litres × 14.53 × 10⁻³ L

No of moles = 1.498 × 10⁻³ L

Now, number of millimoles = 1.498 × 10⁻³ L × 1000 (millimoles = moles × 1000)

Number of millimoles = 1.498

c.

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