Recap - Bromide in Brine

Part of the Stoichiometry section of Coddy's Chemistry journey. Lesson 34 of 41.

Challenge

Israel is one of the world's largest producers of bromine. Its source is the Dead Sea: the brine pumped from it holds about 4.0 g of bromide ions, Br⁻, in every liter, some sixty times more than ordinary seawater.

To take the bromine out, chlorine gas is bubbled through the brine. The chlorine takes the place of the bromide in solution, and bromine, Br₂, a dark red liquid, is set free and collected:

Cl₂(g) + 2Br⁻(aq) → 2Cl⁻(aq) + Br₂(l)

A beaker of orange Dead Sea brine, 1.0 L, beside a small beaker of dark red liquid bromine

Bromide in the brine becomes bromine, Br₂, a dark red liquid

Bromine is made into fire retardants, medicines and the salts in many lab tests. A plant chemist checks each batch of brine by adding silver nitrate solution, which turns its bromide into a pale yellow solid, silver bromide:

Ag⁺(aq) + Br⁻(aq) → AgBr(s)

The brine holds 4.0 g of Br⁻ ions per liter, c_m. Calculate the molar concentration of bromide ions, $c$ (Br, 80 g/mol).

Try it yourself