One way the U.S. Environmental Protection Agency (EPA) tests for chloride contaminants in water is by titrating a sample of silver nitrate solution. Any chloride anions in solution will combine with the silver cations to produce bright white silver chloride precipitate. Suppose an EPA chemist tests a 200. mL sample of groundwater known to be contaminated with iron(II) chloride, which would react with silver nitrate solution like this: FeCl₂(aq) + 2 AgNO3(aq) → mg L 2 AgCl(s) + Fe Fe(NO3)₂(aq) The chemist adds 28.0 mM silver nitrate solution to the sample until silver chloride stops forming. He then washes, dries, and weighs the precipitate. He finds he has collected 7.6 mg of silver chloride. Calculate the concentration of iron(II) chloride contaminant in the original groundwater sample. Round your answer to 2 significant digits. X
Thermochemistry
Thermochemistry can be considered as a branch of thermodynamics that deals with the connections between warmth, work, and various types of energy, formed because of different synthetic and actual cycles. Thermochemistry describes the energy changes that occur as a result of reactions or chemical changes in a substance.
Exergonic Reaction
The term exergonic is derived from the Greek word in which ‘ergon’ means work and exergonic means ‘work outside’. Exergonic reactions releases work energy. Exergonic reactions are different from exothermic reactions, the one that releases only heat energy during the course of the reaction. So, exothermic reaction is one type of exergonic reaction. Exergonic reaction releases work energy in different forms like heat, light or sound. For example, a glow stick releases light making that an exergonic reaction and not an exothermic reaction since no heat is released. Even endothermic reactions at very high temperature are exergonic.
Given,
an EPA chemist tests a 200. mL sample of groundwater known to be contaminated with iron(II) chloride, which would react with silver nitrate solution like this:-
FeCl2(aq)+2AgNO3(aq) -----> 2AgCl(s)+ Fe(NO3)2(aq)
The chemist adds 28.0 mM silver nitrate solution to the sample until silver chloride stops forming. He then washes, dries, and weighs the precipitate. He finds he has collected 7.6 mg of silver chloride.
The 28.0mM concentration of the silver nitrate solution is not important since it is added in excess to precipitate out all of the silver chloride.
Step by step
Solved in 2 steps
