# How many millilitres of 0.200 M NaOH are required to neutralize 20.0 ml of 0.100 M HCl? Enter only a numerical value, do not enter units.?

How many millilitres of 0.200 M NaOH are required to neutralize 20.0 ml of 0.100 M HCl?
Enter only a numerical value, do not enter units.?

• Since weāre looking for the amount of NaOH needed, we will start with the HCl and convert it into the NaOH. It is important to know the chemical reaction that is occurring: 1HCl + 1NaOH ā> 1NaCl + 1H2O

We know that we have 20 mL. And we also know the we have 0.100 M. I can rewrite the 0.100 M as

(0.100 mol / 1 L) because M = mol / L OR M = L / mol.

So now, I see that if I can get rid of that L, then I will know how many mols of HCl I have.

To do this, I will take the 20 mL, convert it into L by dividing by 1000.

Then I multiply the 0.020 L by the (0.100 mol / 1L) and I see that I now have 0.002 mols of HCl.

Now I use the chemical reaction to convert from HCl to NaOH. Youāll notice that It is a 1 to 1 conversion meaning that 1 mol of HCl will react with 1 mol of NaOH to make the products. This means that if I have 0.002 mols of HCl, it will neutralize 0.002 mols of NaOH.

Remember that part when I said M = L / mol? I can use this to find the amount of NaOH I need. So I multiply the 0.002 mols of NaOH with (1 L / 0.200 mols NaOH) = 0.01 L which I can then convert into mL by multiplying by 1000 to get 100 mL.

I know the text way makes it seem complicated. But all I did was multiply 5 times. I attached the mathematical representation of what I did. Notice how the top of the one fraction always matches the bottom of the next fraction. This allows my units to convert.

• 0.01L x 1000 = 10