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

1 Answer
Truong-Son N.
May 3, 2017

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

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