Calculate the molarity of a sulfuric acid solution containing 24.4g of sulfuric acid in 198g of water. The molar mass of sulfuric acid is 98.09
The Correct Answer and Explanation is:
To calculate the molarity (M) of a sulfuric acid solution, we need to know the number of moles of solute (sulfuric acid, H₂SO₄) and the volume of the solution in liters.
Step 1: Calculate moles of sulfuric acid
Given:
- Mass of sulfuric acid = 24.4 g
- Molar mass of sulfuric acid (H₂SO₄) = 98.09 g/mol
Moles of H₂SO₄=massmolar mass=24.4 g98.09 g/mol≈0.249 mol\text{Moles of H₂SO₄} = \frac{\text{mass}}{\text{molar mass}} = \frac{24.4 \text{ g}}{98.09 \text{ g/mol}} \approx 0.249 \text{ mol}Moles of H₂SO₄=molar massmass=98.09 g/mol24.4 g≈0.249 mol
Step 2: Estimate volume of solution in liters
We are given the mass of water, not the volume of the entire solution. However, since this is a dilute aqueous solution, we can assume the density of water is approximately 1.00 g/mL. The mass of water is 198 g, which is about 198 mL of water. After adding sulfuric acid (24.4 g), the total mass is 222.4 g.
Assuming the final volume is roughly equivalent to its mass (reasonable for dilute solutions), the volume of the solution is about 222.4 mL, which is:222.4 mL=0.2224 L222.4 \text{ mL} = 0.2224 \text{ L}222.4 mL=0.2224 L
Step 3: Calculate molarity
Molarity (M)=moles of soluteliters of solution=0.2490.2224≈1.12 M\text{Molarity (M)} = \frac{\text{moles of solute}}{\text{liters of solution}} = \frac{0.249}{0.2224} \approx 1.12 \text{ M}Molarity (M)=liters of solutionmoles of solute=0.22240.249≈1.12 M
Final Answer:
The molarity of the sulfuric acid solution is 1.12 M
Explanation
Molarity is a unit that expresses the concentration of a solution. It is defined as the number of moles of solute per liter of solution. In this question, sulfuric acid is the solute and water is the solvent. The problem provides the mass of sulfuric acid and water. To determine molarity, the number of moles of sulfuric acid is calculated first using its molar mass. The molar mass of sulfuric acid is 98.09 grams per mole. Dividing the mass of sulfuric acid, 24.4 grams, by its molar mass gives approximately 0.249 moles.
The next step involves estimating the volume of the solution. Since the density of water is approximately 1 gram per milliliter, 198 grams of water is estimated to be 198 milliliters. Adding the 24.4 grams of sulfuric acid increases the total mass to about 222.4 grams. In dilute solutions like this, we can assume the final volume is close to the mass in milliliters, making the volume about 222.4 milliliters, or 0.2224 liters.
Finally, molarity is found by dividing the moles of sulfuric acid (0.249) by the volume of the solution in liters (0.2224). This gives a result of approximately 1.12 molar. This means that each liter of the solution contains 1.12 moles of sulfuric acid. Understanding how to calculate molarity is important in chemistry because it allows chemists to prepare and work with solutions of known concentration, which is essential in reactions and laboratory experiments.
