What is the percent by mass of #"12 M HCl"#?

1 Answer
Truong-Son N.
May 3, 2017

Knowing the concentration is about #"12 M"# (it's specifically about #"12.06 M"#), we can assume a volume of #"1 L"# to calculate the mass density.

#(12 cancel"mols HCl")/"L solution" xx "36.4609 g"/cancel"mol HCl" = "437.5308 g HCl"/"L solution"#

Based on the mass density, we can calculate the mass percent by converting the solution volume to its mass.

#("437.5308 g HCl")/cancel"L solution" xx cancel("1 cm"^(3))/("1.17 g solution") xx cancel"1 mL"/cancel("1 cm"^(3)) xx cancel"1 L"/(1000 cancel("mL")#

#= 0.374#

Or, about #color(blue)("37.4% w/w")#. Note that #37%# is actually reagent-grade, not commercial-grade, which is about #39%#.

See if you can calculate the concentration in #39%# commercial-grade HCl! HINT: Use a ratio of the molar concentrations of the #37%# to the #39%#, and assume the density is similar enough.

Related questions
See all questions in Percent Concentration
Impact of this question
7950 views around the world
You can reuse this answer
Creative Commons License