In 2014, a major chemical leak at a facility in West Virginia released 28,390 L of MCHM (4-methylcyclohexylmethanol, C8H16O) into the Elk River. The density of MCHM is 0.9074 g/mL. (a) Calculate the initial molarity of MCHM in the river, assuming that the first part of the river is 2.00 m deep, 90.0 m wide, and 90.0 m long.
Ch.4 - Reactions in Aqueous Solution
Chapter 4, Problem 113a
The arsenic in a 1.22-g sample of a pesticide was converted to AsO43- by suitable chemical treatment. It was then titrated using Ag+ to form Ag3AsO4 as a precipitate. (a) What is the oxidation state of As in AsO43-?

1
Identify the chemical formula of the arsenate ion, AsO4^{3-}, and note that it contains arsenic (As) and oxygen (O).
Recall that the oxidation state of oxygen is typically -2 in most compounds.
Set up an equation to find the oxidation state of arsenic (As). Let the oxidation state of As be x. The formula for the arsenate ion is AsO4^{3-}, which means the overall charge is -3.
Write the equation for the sum of oxidation states: x + 4(-2) = -3, where x is the oxidation state of As and -2 is the oxidation state of each oxygen atom.
Solve the equation for x to determine the oxidation state of arsenic in AsO4^{3-}.

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The arsenic in a 1.22-g sample of a pesticide was converted to AsO43- by suitable chemical treatment. It was then titrated using Ag+ to form Ag3AsO4 as a precipitate. (b) Name Ag3AsO4 by analogy to the corresponding compound containing phosphorus in place of arsenic.
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