Calculate the volume of concentrated HCl needed to prepare 250 mL of 0.1M HCl. (Concentrated HCl has a density of 1.188 g mL–1 and is 37 wt %).

Question

can anyone please help me with this question, I have tried it I got volume= 0.8 M

Answer 1

First, you need to determine the number of moles of HCl that is contained in 250 mL of a 0.1 M HCl solution. This can be achieved by:

(0.1 mol HCl/L) * (.25 L) = 0.025 mol HCl [Recall that molarity, M = (mol substance)/(L of solution)]

Next, determine the mass of HCl that corresponds to 0.025 mol HCl. You need the molar mass of HCl to do this: (0.025 mol HCl) x (36.45 g HCl/1 mol HCl) = 0.911 g HCl

The 37wt% essentially means that every 1 g of conc. HCl solution contains 0.37 g HCl. Since you need 0.911 g HCl, you need to determine the mass of conc. HCl soluiton you need:

(0.911 g HCl)(1 g conc. HCl/0.37 g HCl) = 2.46 g conc. HCl solution.

Now, since the density of the conc. HCl solution is 1.188 g/mL, then you can finally determine the volume of conc. HCl needed:

(2.46 g conc. HCl solution)(1 mL/1.188 g HCl solution) = 2.07 mL conc. HCl solution

Hope this helps!