Question

Muriatic acid, an industrial grade of concentrated HCl, is used to clean masonry and cement. Its concentration is 11.7 M. (a) Write instructions for diluting the concentrated acid to make 3.0 gallons of 3.5 M acid for routine use (1 gal = 4 qt; 1 qt = 0.946 L). (b) How many milliliters of the muriatic acid solution contain 9.66 g of HCl?

Short answer

a. The first step is to prepare a 3.396 L of 11.7 M HCl, and water can be added till it reaches a volume of 11.352 L to get a diluted acid concentration of 3.5 M.

b. The muriatic acid solution that contains 9.66 g of HCl is 22.6 mL of HCl solution.

Step-by-step solution

 Step 1: Instruction for concentrated acid dilution

On converting the given volume, we get:

$$\begin{gathered} V_{dil} of so\ln =3 gal so\ln \times \frac{4 qt so\ln }{1 gal so\ln }\times \frac{0.946 L so\ln }{1 qt so\ln } \\ =11.352 L s\ln \\ V_{conc}=\frac{M_{dil}\times V_{dil}}{M_{conc}} \\ =\frac{3.5 M\times 11.352 L}{11.7 m} \\ =3.396 L solution. \end{gathered}$$

The first step is to prepare a 3.396 L of 11.7 M HCl, and water can be added till it reaches a volume of 11.352 L to get a diluted acid concentration of 3.5 M.

finding volume of HCl

On converting the given mass of HCl to moles, we get:

$\begin{array}{rcl} Moles of HCl& =& 9.66 g HCl\times \frac{1 mol HCl}{36.46 g HCl}\\ & =& 0.265 mol HCl\\ Volume of HCl& =& \frac{0.265 mol HCl}{11.7\frac{mol HCl}{L so\ln }}\\ & =& 0.0226 L solution\\ & =& 22.6 mL solution.\end{array}$