Question

A solution of licl in water has xlicl = 0.0900. what is the molality?

Answer 1

Given that a one mol solution of lithium chloride has 0.0900 mol of lithium chloride dissolved in it. Which implies that 0.910 mol of water has dissolved 0.0900 mol of Lithium chloride. which implies 0.910*18g of water has 0.0900mol LiCl. Molality is given by moles of solute divided by kg of solvent. so 1 kg of water has (0.0900*1000)/(0.910*18) mol of LiCl. or 5.4945 molal solution. So molality is 5.4945

Answer 2

The molality of LiCl solution is $\boxed{{\text{5}}{\text{.4945 m}}}$  

Further Explanation:

The amount of substance in any mixture is termed as its concentration. Some of the most commonly used concentration terms are as follows:

1. Molarity (M)

2. Molality (m)

3. Mole fraction (x)

4. Parts per million (ppm)

5. Mass percent ((w/w) %)

6. Volume percent ((v/v) %)

The relation between the molality and the mole fraction of the solution is as follows:

${\text{m}} = \dfrac{{{{\text{x}}_{\text{B}}}{\text{ \times 1000}}}}{{{{\text{x}}_{\text{A}}}{{\text{M}}_{\text{A}}}}}$    …… (1)                                                          

Here,

m is the molality of solution.

${{\text{x}}_{\text{A}}}$ is the mole fraction of solvent.

${{\text{x}}_{\text{B}}}$ is the mole fraction of solute.

${{\text{M}}_{\text{A}}}$ is the molar mass of solvent.

The expression that relates the mole fraction of solute and solvent is,

${{\text{x}}_{\text{A}}} + {{\text{x}}_{\text{B}}} = {\text{1}}$  …… (2)                                                                                  

Rearrange equation (2) to calculate ${{\text{x}}_{\text{A}}}$.

${{\text{x}}_{\text{A}}} = {\text{1}} - {{\text{x}}_{\text{B}}}$  …… (3)                                                                              

Substitute 0.0900 for ${{\text{x}}_{\text{B}}}$ in equation (3).

$\begin{aligned}{{\text{x}}_{\text{A}}}&= {\text{1}} - {\text{0}}{\text{.0900}}\\&= {\text{0}}{\text{.91}}\\\end{aligned}$  

Substitute 0.0900 for ${{\text{x}}_{\text{B}}}$, 0.91 for ${{\text{x}}_{\text{A}}}$ and 18 g/mol for ${{\text{M}}_{\text{A}}}$ in equation (1) to calculate the molality of LiCl solution.

 $\begin{aligned}{{\text{m}}_{{\text{LiCl}}}} &= \frac{{\left( {0.0900} \right)\left( {{\text{1000}}} \right)}}{{\left( {0.91} \right)\left( {18{\text{ g/mol}}} \right)}}\\&= 5.4945{\text{ m}}\\\end{aligned}$

Therefore molality of LiCl solution is 5.4945 m.

Learn more:

1. What is the mass of 1 mole of viruses: brainly.com/question/8353774
2. Determine the moles of water produced: brainly.com/question/1405182

Answer details:

Grade: Senior School

Subject: Chemistry

Chapter: Concentration terms

Keywords: molality, mole fraction, solute, solvent, molar mass, LiCl, 5.4945 m, 18 g/mol, 0.91, 0.0900, molality of solution, xA, xB, MA, molarity, mass percent, volume percent, parts per million.