Math Problem Statement

A solution is 0.0480 m LiF. What is the molarity of the solution if the density is 1.10 g/mL?

Solution

To find the molarity (MM) of the solution, we'll use the relationship between molality (mm), density, and molarity. Here’s the step-by-step process:

Given:

  • Molality (mm) = 0.0480 mm (mol/kg of solvent)
  • Density (ρ\rho) = 1.10 g/mL = 1.10 kg/L
  • Molar mass of LiF (Lithium Fluoride) ≈ 25.94 g/mol

Step 1: Find the mass of the solution per liter.

The density gives us the mass of the solution per unit volume. Since density is 1.10 g/mL, this converts to:

Mass of 1 L solution=1.10kg\text{Mass of 1 L solution} = 1.10 \, \text{kg}

Step 2: Calculate the mass of the solvent in 1 liter of solution.

Let's assume we have 1 liter of solution.

Mass of solvent=Total mass of solutionMass of solute\text{Mass of solvent} = \text{Total mass of solution} - \text{Mass of solute}

To find the mass of the solute: Molality=moles of solutemass of solvent in kg\text{Molality} = \frac{\text{moles of solute}}{\text{mass of solvent in kg}} Let's assume the mass of the solvent is xx kg. Then:

Moles of LiF=0.0480×x\text{Moles of LiF} = 0.0480 \times x

The mass of the solute (LiF) is:

Mass of solute=moles of LiF×molar mass of LiF\text{Mass of solute} = \text{moles of LiF} \times \text{molar mass of LiF}

Mass of solute=0.0480×x×25.94g/mol\text{Mass of solute} = 0.0480 \times x \times 25.94 \, \text{g/mol}

So the total mass of the solution is:

Mass of solution=xkg+0.0480×x×25.94g\text{Mass of solution} = x \, \text{kg} + 0.0480 \times x \times 25.94 \, \text{g}

Given that the total mass of the solution for 1 L is 1.10 kg:

1.10=x+0.0480×x×25.941.10 = x + 0.0480 \times x \times 25.94

Solving for xx:

1.10=x(1+0.0480×25.94)1.10 = x(1 + 0.0480 \times 25.94) 1.10=x(1+1.246)1.10 = x(1 + 1.246) x=1.102.2460.4894kgx = \frac{1.10}{2.246} \approx 0.4894 \, \text{kg}

So the mass of the solvent is approximately 0.4894 kg.

Step 3: Calculate the moles of LiF in the solution.

Moles of LiF=0.0480×0.48940.0235moles\text{Moles of LiF} = 0.0480 \times 0.4894 \approx 0.0235 \, \text{moles}

Step 4: Find the molarity (MM) of the solution.

Molarity is the number of moles of solute per liter of solution:

M=Moles of LiFVolume of solution in liters=0.0235moles1L=0.0235MM = \frac{\text{Moles of LiF}}{\text{Volume of solution in liters}} = \frac{0.0235 \, \text{moles}}{1 \, \text{L}} = 0.0235 \, M

Thus, the molarity of the solution is approximately 0.0235 M.

Would you like more details or have any other questions?

Here are some related questions:

  1. How do you convert between molarity and molality?
  2. What is the effect of temperature on the density and molarity of a solution?
  3. How would you calculate the volume of solution needed to obtain a certain amount of solute?
  4. What role does the density of the solution play in determining concentration?
  5. Can you find the molality of a solution if you are given the molarity and density?

Tip: Always remember to check the units during conversion, especially when dealing with molarity and molality.

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Math Problem Analysis

Mathematical Concepts

Chemistry
Solution Concentrations
Molarity
Density

Formulas

Molarity (M) = moles of solute / volume of solution (in liters)

Theorems

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Suitable Grade Level

High School