Calculate the amount of 5.00 M HCl needed to make 50.0 mL of 1.00 M HCl.

Molarity is the ratio of moles of solute to the volume (in liters) of the solvent. Thus, a 1 molar (or 1 M) solution contains 1 mole of a solute dissolved in 1 liter of a solvent. 

Here, we are given 5 M HCl (hydrochloric acid) solution and we have to prepare 50 ml of 1 M solution from it. Since the given solution has a higher concentration (5 M), we can dilute it to get a lower concentration (1 M) solution. An easy way to do so is to calculate the number of moles of solute in both the solutions and use it to calculate the required volume.

Molarity = moles / volume

or, moles = molarity x volume = 1 M x 50 ml x 1 lt/1000 ml = 0.05 moles

Thus, 50 ml, 1 M HCl contains 0.05 moles of HCl.

The volume of 5 M HCl that contains the same number of moles of HCl is:

volume = moles/molarity = 0.05 / 5 = 0.01 liter x 1000 ml/liter = 10 ml.

Thus, 10 ml of 5 M HCl is used to prepare 50 ml 1 M solution. We need to mix 40 ml of water to 10 ml of 5 M HCl to get the required solution.

Hope this helps.