Question

An aqueous solution of potassium hydroxide has a concentration of 0.372 molal.

The percent by mass of potassium hydroxide in the solution is _______%.

An aqueous solution is 22.0% by mass silver nitrate, AgNO₃, and has a density of 1.22 g/mL.

The molality of silver nitrate in the solution is _______m.

Answer 1

An aqueous solution of potassium hydroxide has a concentration of 0.372 molal.

Molar mas of KOH=56.1g/mol

Molaity is number of moles of solute in 1 kg of solvent:

Let there be a solution that has 1 kg solvent in it

therefore 0.372 moles of KOH are present in 1kg solvent

therefore, 0.372*56.1 g of KOH is present in 1 kg solvent

or, 20.87g KOH is present in 10000g solvent

Hence mass percent of KOH is given by

The percent by mass of potassium hydroxide in the solution is __2.04_____%.

An aqueous solution is 22.0% by mass silver nitrate, AgNO₃, and has a density of 1.22 g/mL.

Let us take 1 L of the given solution as the basis

THerefore:

Volume of solution=1L

Mass of solution =1220g

Since mass% of silver nitrate=22%

therefore mass of silver nitrate =0.22*1220=268.4g

moles of silver nitrate is given by :

n=w/M

=>n=268.4/169.87=1.58

Since molarity is given by moles of solut per liter of solution hence, molarity of the above solution is

Molarity=n/V=1.58/1=1.58M

The molality of silver nitrate in the solution is __1.58_____m.