A solution of 0.211 M NaOH is used to titrate 24.0 mL of a H2SO4 solution. If 19.0 mL of the NaOH solution is required to reach the endpoint, what is the molarity of the H2SO4 solution?
H2SO4(aq)+2NaOH(aq)→2H2O(l)+NaSO4(aq)
mols NaOH = M x L = ?
Look at the equation. mols H2SO4 = 1/2 mols NaOH
Then M H2SO4 = mols H2SO4/L H2SO4.
To find the molarity of the H2SO4 solution, we can use the concept of stoichiometry and the balanced equation. Here's how you can solve it step-by-step:
Step 1: Write down the balanced equation:
H2SO4(aq) + 2NaOH(aq) → 2H2O(l) + Na2SO4(aq)
Step 2: Find the number of moles of NaOH used:
The given volume of NaOH solution used to reach the endpoint is 19.0 mL. Since the molarity of NaOH is 0.211 M, we can calculate the moles of NaOH used as follows:
moles of NaOH = Molarity × Volume
moles of NaOH = 0.211 M × 19.0 mL = 0.004009 moles
Step 3: Use the stoichiometry of the balanced equation to relate the moles of NaOH to H2SO4:
From the balanced equation, we know that the ratio of NaOH to H2SO4 is 2:1. Therefore, the moles of H2SO4 used is half the moles of NaOH:
moles of H2SO4 = 0.004009 moles ÷ 2 = 0.002005 moles
Step 4: Calculate the molarity of the H2SO4 solution:
The molarity of a solution is calculated by dividing the moles of solute by the volume of the solution in liters. The volume of the H2SO4 solution is given as 24.0 mL, so first, we convert it to liters:
Volume of H2SO4 solution in liters = 24.0 mL ÷ 1000 = 0.024 L
Now we can calculate the molarity of the H2SO4 solution:
Molarity of H2SO4 = moles of H2SO4 ÷ Volume of H2SO4 solution in liters
Molarity of H2SO4 = 0.002005 moles ÷ 0.024 L = 0.0835 M
Therefore, the molarity of the H2SO4 solution is 0.0835 M.