Physical Chemistry Answers

A solution made from pure Potassium hydroxide contained 1.85 g of Potassium

hydroxide in exactly 200 cm 3 of water. Using phenolphthalein indicator, titration of 20.0

cm 3 of this solution is carried out v/s sulphuric acid. 9.35 cm 3 of sulphuric acid solution is

required for complete neutralisation. [atomic masses: K= 39, O = 16, H = 1]

(a) write the equation for the titration reaction.

(b) calculate the molarity of the Potassium hydroxide solution.

(c) calculate the moles of Potassium hydroxide neutralised.

(d) calculate the moles of sulphuric acid neutralised.

(e) calculate the molarity of the sulphuric acid.

a) Calculate the molarity of a 5 ppm pesticide solution if the molar mass of the pesticide 435 g/mol. Q6) b) Seawater contains 3.90 x 10¯3 ppb of dissolved gold. What volume (in litres) of this seawater would contain 100 g of gold?

The solubility of Ca(OH)2·8H2O in water at 25◦C is 1.73 g per litre. What is the formality and molality of a saturated solution at 25◦C, assuming it to be a very dilute solution? [Ca = 40, O = 16 and H = 1] 

4.06 g of impure magnesium oxide was completely dissolved in 100 cm3 of hydrochloric acid, of concentration 2.00 mol dm-3 (in excess).The excess acid required 19.7 cm3 of sodium hydroxide (0.200 mol dm-3) for neutralisation using phenolphthalein indicator and the end-point is the first permanent pink colour.This 2nd titration is called a 'back titration’ and is used to determine the unreacted acid.a)Why do you have to use excess acid and employ a back titration?write equations for the two neutralisation reactions.b) calculate the moles of hydrochloric acid added to the magnesium oxide.c) calculate the moles of excess hydrochloric acid titrated.d) calculate the moles of hydrochloric acid reacting with the magnesium oxide.e) calculate the moles and mass of magnesium oxide that reacted with the initial hydrochloric acid.f) hence the % purity of the magnesium oxide.g) what compounds could be present in the magnesium oxide that could lead to a false value of its purity? explain

In our college laboratory a container containing 5 litres of a commercial sample of hydrochloric acid (36.2 % by weight with a density of 1.19 g/ml) developed a crack and all the HCl was spilt on the floor. It can be neutralised with limestone powder.

[atomic masses: Ca = 40, C = 12, O = 16]

(a) Write the equation for the reaction between limestone and hydrochloric acid.

(b) How many moles of hydrochloric acid was spilt?

(c) How many moles of calcium carbonate will neutralise the acid?

(d) What minimum mass of limestone powder is needed to neutralise the acid if the limestone is 70% pure?

A solution made from pure Potassium hydroxide contained 1.85 g of Potassium hydroxide in exactly 200 cm3 of water. Using phenolphthalein indicator, titration of 20.0 cm3 of this solution is carried out v/s sulphuric acid. 9.35 cm3 of sulphuric acid solution is required for complete neutralisation. [atomic masses: K= 39, O = 16, H = 1] (a) write the equation for the titration reaction. (b) calculate the molarity of the Potassium hydroxide solution. (c) calculate the moles of Potassium hydroxide neutralised. (d) calculate the moles of sulphuric acid neutralised. (e) calculate the molarity of the sulphuric acid

Q1) A solution made from pure Potassium hydroxide contained 1.85 g of Potassium 

hydroxide in exactly 200 cm3

 of water. Using phenolphthalein indicator, titration of 20.0 

cm3

 of this solution is carried out v/s sulphuric acid. 9.35 cm3

 of sulphuric acid solution is 

required for complete neutralisation. [atomic masses: K= 39, O = 16, H = 1]

(a) write the equation for the titration reaction.

(b) calculate the molarity of the Potassium hydroxide solution.

(c) calculate the moles of Potassium hydroxide neutralised.

(d) calculate the moles of sulphuric acid neutralised.

(e) calculate the molarity of the sulphuric acid.