10.0 mL of HCl and a few drops of phenolphthalein indicator. The buret contains 0.110 M NaOH.

What was the initial concentration of HCl?

My crystal ball isn't working well today. You don't have nearly enough information to answer a question. You need volume NaOH. Use this

mL HCl x M HCl = mL NaOH x M NaOH and solve for the M HCl. Post your work if you get stuck.

To determine the initial concentration of HCl, we can use the concept of stoichiometry and the balanced chemical equation for the reaction between HCl and NaOH.

The balanced chemical equation for the reaction is:
HCl + NaOH → NaCl + H2O

From the equation, we can see that the stoichiometric ratio between HCl and NaOH is 1:1. This means that each mole of HCl reacts with one mole of NaOH.

Given that the initial volume of HCl is 10.0 mL and the initial concentration of NaOH is 0.110 M, we need to determine the volume of NaOH required to completely react with the HCl.

To find the volume of NaOH, we can use the equation:
moles of HCl = concentration of HCl × volume of HCl (in liters)

Since the volume of HCl is given in milliliters, we need to convert it to liters by dividing by 1000:
volume of HCl (in liters) = 10.0 mL ÷ 1000 = 0.0100 L

Now, we can calculate the moles of HCl:
moles of HCl = concentration of HCl × volume of HCl (in liters)
moles of HCl = ? × 0.0100 L

Next, we can use the stoichiometry of the balanced equation to find the moles of NaOH required to react with the given moles of HCl:
moles of NaOH = moles of HCl

Finally, we can use the concentration and volume of NaOH to find its initial concentration:
volume of NaOH (in liters) = moles of NaOH ÷ concentration of NaOH

Substituting the values into the equation:
volume of NaOH (in liters) = ? ÷ 0.110 M

Solving for the initial concentration of HCl requires knowing the volume of NaOH used to neutralize the HCl solution. Without that information, we cannot determine the initial concentration of HCl.