Question

1.calculate the volume of 50% NaOH required to make 300 mL of a 0.1 M NaOH solutions 2.Calculate the standard potassium hydrogen phthalate required to react with 25 mL of a 0.1 M NaOH solution 2. Calculate the mass of the standard potassium hydrogen phthalate required to react with 25 mL of a 0.1 M NaOH solution.

Answer 1

1.calculate the volume of 50% NaOH required to make 300 mL of a 0.1 M NaOH solutions ution

Solution :- lets first calculate the moles of the NaOH in 300 ml solution

Moles = molarity * volume in liter

            = 0.1 mol per L * 0.300 L

           = 0.03 mol

Mass of NaOH = moles * molar mass

                            = 0.03 mol * 40.0 g per mol

                            = 1.2 g

Now lets calculate the volume of 50 % solution

1.2 g * 100 ml / 50 g = 2.4 ml

So we need to use 2.4 ml of the 50 % solution to make the desired NaOH solution .

2. Calculate the mass of the standard potassium hydrogen phthalate required to react with 25 mL of a 0.1 M NaOH solution.

Solution :-

Moles ratio of the KHP and NaOH is 1 :1

So lets calculate the moles of the NaOH in 25.0 ml solution

Moles of NaOH = molarity * volume oin liter

                             = 0.1 mol per L * 0.025 L

                             = 0.0025 mol NaOH

So the moles of the KHP needed are same as moles of NaOH

Moles of KHP = 0.0025 mol

Mass of KHP = moles * molar mass

                       = 0.0025 mol * 204.22 g per mol

                        = 0.511 g KHP

So the mass of KHP needed is 0.511 g