15.00 ml of NaOH is obtained in an Erlenmeyer flask. Before titrating with .2500 M HCl, the initial volume of acid in a buret is read as 2.08 ml. At the endpoint the final volume of acid in the buret is 25.20 ml. What was the concentration of NaOH?
mols HCl = M x L.
M you have as 0.2500.
L. Final 25.20mL - 2.08 mL = mL HCl. Convert to L and find mols as above.
Then mols NaOH = mols HCl.
M NaOH = mols NaOH/L NaOH. Solve for M.
To determine the concentration of NaOH, we can use the concept of titration. In a titration, a known concentration of one solution is used to react with an unknown concentration of another solution until a chemical reaction reaches completion. In this case, we are titrating a solution of NaOH with HCl.
Let's break down the information provided:
Initial volume of HCl: 2.08 ml
Final volume of HCl: 25.20 ml
The difference between the initial and final volumes of HCl will give us the volume of HCl used in the titration:
Volume of HCl used = Final volume - Initial volume
= 25.20 ml - 2.08 ml
= 23.12 ml
Now, we need to determine the moles of HCl used. Since the concentration of HCl is given as 0.2500 M, we can use the equation:
Molarity (M) = Moles (mol) / Volume (L)
Rearranging the equation, we get:
Moles (mol) = Molarity (M) * Volume (L)
Converting the volume of HCl used to liters:
Volume of HCl used (L) = 23.12 ml * (1 L / 1000 ml)
= 0.02312 L
Now we can calculate the moles of HCl:
Moles of HCl = 0.2500 M * 0.02312 L
= 0.00578 mol
According to the balanced chemical equation for the reaction between NaOH and HCl, the molar ratio is 1:1. This means that for every mole of HCl used, there is one mole of NaOH. Therefore, the moles of NaOH are also 0.00578 mol.
Finally, to find the concentration of NaOH, we need to calculate the molarity using the formula:
Molarity (M) = Moles (mol) / Volume (L)
The volume of NaOH is given as 15.00 ml, so converting to liters:
Volume of NaOH (L) = 15.00 ml * (1 L / 1000 ml)
= 0.01500 L
Now we can calculate the concentration of NaOH:
Molarity of NaOH = 0.00578 mol / 0.01500 L
= 0.3853 M
Therefore, the concentration of NaOH is approximately 0.3853 M.