14.6 mL of hydrochloric acid is completely neutralized by 25.0 mL of 1.40 M sodium hydroxide, what was the hydrochloric acid mass percent (m/m) before the titration? (Density of hydrochloric acid is 1.02 g/cm3)
First determine the molarity of the HCl.
mols NaOH = M x L = ?
mols HCl = mols NaOH
M HCl = mols HCl/L solution. You know mols and L(convert mL to L), solve for M.
M HCl means mols/L solution
Convert mols HCl to grams HCl. mols = grams/molar mass. You know molar mass and mols, solve for grams. That gives you grams HCl/1000 mL solution. Use density to convert 1000 mL to grams solution and g HCl/g solution will give
you g HCl/1020 g solution. That x 100 gives you % HCl m/m
I think the answer is approx 10% m/m
To calculate the mass percent of hydrochloric acid before the titration, we need to find the mass of hydrochloric acid and the total mass of the solution.
Let's break down the steps to solve this problem:
Step 1: Find the volume of hydrochloric acid (HCl) in liters.
Given: Volume of HCl = 14.6 mL
We need to convert mL to liters by dividing the volume by 1000:
Volume of HCl = 14.6 mL / 1000 mL/L = 0.0146 L
Step 2: Calculate the mass of hydrochloric acid (HCl) in grams.
Given: Density of HCl = 1.02 g/cm³
We know that the density is the mass per unit volume, so we can rearrange the formula:
Mass = Density × Volume
Mass of HCl = 1.02 g/cm³ × 0.0146 L = 0.0149 g
Step 3: Determine the total mass of the solution.
To find the total mass, we need to consider the mass of both the hydrochloric acid and sodium hydroxide solution (after complete neutralization). Since the volumes for both are given, we can assume they mix without a significant volume change. Therefore, the total volume of the solution is the sum of the volumes of HCl and NaOH, which is 14.6 mL + 25.0 mL = 39.6 mL.
To convert mL to grams, we use the density of hydrochloric acid:
Total mass of the solution = Total volume × Density
Total mass of the solution = 39.6 mL × 1.02 g/cm³ = 40.392 g
Step 4: Calculate the mass percent (m/m) of HCl.
Mass percent (m/m) = (Mass of HCl / Total mass of the solution) × 100
Mass percent (m/m) = (0.0149 g / 40.392 g) × 100 ≈ 0.0368% (rounded to four decimal places)
Therefore, the mass percent (m/m) of hydrochloric acid before the titration is approximately 0.0368%.