How do we dilute concentrated hydrochloric acid to give 10% #HCl#?

2 Answers
Mar 2, 2017

Answer:

Carefully, and YOU ALWAYS ADD ACID TO WATER..........You also wear a lab coat and a pair of safety spex..................

Explanation:

#38%# #HCl# is as far as I know the most concentrated hydrochloric acid solution you can get.

The reported concentrations must be: #"mass of HCl"/"mass of solution"xx100%.#

And thus you add #"1 part acid"# to #"3 parts"# water by volume. The order of addition is IMPORTANT.

Mar 21, 2017

Answer:

You add 260 mL of the 38 % acid to enough water to make 1 L.

Explanation:

Let's say you wanted to prepare 1 L of 10 % #"HCl"#.

Since you are using solutions with the same concentration units, you don’t need the density information.

You can simply use the dilution formula

#color(blue)(bar(ul(|color(white)(a/a) c_1V_1 = c_2V_2color(white)(a/a)|)))" "#

We can rearrange this formula to get

#V_1 = V_2 × c_2/c_1#

In your problem,

#c_1 = 38 %; V_1 = ?#
#c_2 = 10 %; V_2 = "1 L"#

#V_1 = "1 L" × (10 color(red)(cancel(color(black)(%))))/(38 color(red)(cancel(color(black)(%)))) = "0.26 L" = "260 mL"#

Thus, you would slowly and carefully add 260 mL of the 38 % acid to about 500 mL of distilled water in a volumetric flask, always swirling gently to make sure that the acid is evenly mixed.

Then you would add more distilled water until the level just reaches the 1 L mark on the flask.