10ml of HCl acid titrate with 9.9ml of NaOH. What is the mass in grams of HCl?

HCl + NaOH ==> NaCl + H2O

You don't have enough information to work a problem. You must know the M of either the HCl or the NaOH.

To find the mass of HCl, we need to use the concept of stoichiometry and the principle of titration. Here's how we can calculate it step by step:

Step 1: Determine the concentration of NaOH.
The balanced chemical equation for the reaction between HCl and NaOH is:
HCl + NaOH -> NaCl + H2O

The stoichiometry tells us that 1 mole of HCl reacts with 1 mole of NaOH.

From the titration, we know that 9.9 ml of NaOH solution was required to neutralize 10 ml of HCl solution.

Step 2: Calculate the number of moles of NaOH used.
The next step is to convert the volume of NaOH into a number of moles. We need the molarity (concentration) of NaOH solution to do this.

For example, if the NaOH solution is 0.1 M (0.1 moles per liter), we can calculate the number of moles of NaOH as follows:

9.9 ml * (0.1 moles / 1000 ml) = 0.00099 moles of NaOH

Step 3: Calculate the number of moles of HCl.
Since the reaction between HCl and NaOH occurs in a 1:1 ratio, the number of moles of HCl is equal to the number of moles of NaOH used.

So, the number of moles of HCl is also 0.00099 moles.

Step 4: Calculate the mass of HCl.
To calculate the mass of HCl, we need to use the molar mass of HCl, which is approximately 36.46 grams/mol.

Mass of HCl = number of moles * molar mass
Mass of HCl = 0.00099 moles * 36.46 grams/mole
Mass of HCl = 0.03605 grams

Therefore, the mass of HCl in 10 ml of HCl solution is approximately 0.036 grams.