Question

Molarity and molality
solved exmples

Answer 1

Answer:

$\pink{\boxed{\boxed{\boxed{Answer:-}}}}$

$<font color= "Black"> The molarity of the solution is 0.1325 mol L-1 or 0.1325 M, the molality of the solution is 0.1342 mol kg-1 or 0.1342 m. Example – 05: Calculate molarity and molality of the sulphuric acid solution of density 1.198 g cm-3 containing 27 % by mass of sulphuric acid. To Find: Molarity =? and molality =?$

$<marquee behaviour-move><font color="orange"><h1>#itzcutiepie </h1></marquee>$

Answer 2

Answer:

Explanation:

Sample Molality Problem

A 4 g sugar cube (Sucrose: C12H22O11) is dissolved in a 350 ml teacup of 80 °C water. What is the molality of the sugar solution?

Given: Density of water at 80° = 0.975 g/ml

Solution

Start with the definition of molality. Molality is the number of moles of solute per kilogram of solvent.

Step 1 - Determine number of moles of sucrose in 4 g.

Solute is 4 g of C12H22O11

C12H22O11 = (12)(12) + (1)(22) + (16)(11)

C12H22O11 = 144 + 22 + 176

C12H22O11 = 342 g/mol

divide this amount into the size of the sample

4 g /(342 g/mol) = 0.0117 mol

Step 2 - Determine mass of solvent in kg.

density = mass/volume

mass = density x volume

mass = 0.975 g/ml x 350 ml

mass = 341.25 g

mass = 0.341 kg

Step 3 - Determine molality of the sugar solution.

molality = molsolute / msolvent

molality = 0.0117 mol / 0.341 kg

molality = 0.034 mol/kg

Answer:

The molality of the sugar solution is 0.034 mol/kg.

Note: For aqueous solutions of covalent compounds—such as sugar—the molality and molarity of a chemical solution are comparable. In this situation, the molarity of a 4 g sugar cube in 350 ml of water would be 0.033 M.