Exam 4: Solution Chemistry and the Hydrosphere

Controlling the ammonia and ammonium ion concentrations is one of the biggest problems in maintaining a healthy fish aquarium. Ammonia, which is highly toxic to fish because it interferes with their uptake of oxygen, is formed from wastes excreted by the fish, uneaten food, and decaying plants. Beneficial bacteria oxidize the ammonia and ammonium to nitrate, which is not highly toxic to fish in low to moderate levels. Complete and balance the following reaction equation describing the oxidation of ammonium to nitrate ions in acidic solution. NH₄⁺(aq) + O₂(aq)  NO₃^-

Sodium thiosulfate (Na₂S₂O₃, molar mass = 158.2 g/mol) is used in photography. Your summer job is at a photography lab and you need to check the purity of an outdated supply. You react 40.21 mL of 0.246 M iodine solution with a 3.232 g sample. What is the percent purity of the sodium thiosulfate that you report to your boss? I₂(aq) + 2S₂O₃^2-(aq)  2I^-(aq) + S₄O₆^2-(aq)

The drinking water standard of the World Health Organization (WHO) for arsenic is 10.0 g/L. What is this standard in parts per billion (ppb)?

In a demonstration of strong electrolytes, weak electrolytes, and nonelectrolytes, Professor Popsnorkle used a lightbulb apparatus that showed how much a solution conducted electricity by the brightness of the lightbulb. When pure water was tested, the bulb did not light. Then Professor Popsnorkle tested the following aqueous solutions. Which one caused the bulb to burn the brightest?

In which one of the following compounds is the oxidation number of S equal to +4?

Calcium hydroxide is slightly soluble in water. About 1 gram will dissolve in 1 liter. What are the spectator ions in the reaction of such a dilute solution of calcium hydroxide with hydrochloric acid?

Determine the molar concentration of ethanol (C₂H₆O) in a wine that is 14% ethanol by mass. The density of this wine is 0.93 g/cm³.

What mass of silver chloride will be recovered if excess sodium chloride is added to 500 mL of solution containing 10.79 g of Ag⁺?

Lead sinkers used for saltwater fishing do not react with sodium ions in the water. From this we can infer that __________

A cross section of a Mad-Dawg gumball shows an outer layer of citric acid and malonic acid, beneath that a layer of food coloring, sugar, and flavoring, beneath that a layer of sodium bicarbonate (NaHCO₃), and finally in the middle-gum! A 12-year-old puts one in his mouth and immediately puckers, smiles, and then foams at the mouth before chewing. Where did the foam come from?

In its reaction with water, ammonia (NH₃) __________

In a demonstration of strong electrolytes, weak electrolytes, and nonelectrolytes, Professor Popsnorkle used a lightbulb apparatus that showed how much a solution conducted electricity by the brightness of the lightbulb. When pure water was tested, the bulb did not light. Then Professor Popsnorkle tested the following aqueous solutions. Which one caused the bulb to burn dimly but not brightly?

Which picture best represents an atomic-level view of acetic acid, which is a weak acid, in aqueous solution (water molecules not shown)?

In carrying out a titration of a hydrochloric acid solution with a standard sodium hydroxide solution, a student went beyond the end point before reading the volume on the buret. That is, the volume used was larger than the volume required to reach the end point. How will this error affect the calculated concentration of the hydrochloric acid?

A concentrated aqueous ammonia solution has a density of 0.90 g/mL and is 28.0% by mass ammonia. Determine the molar concentration of this solution.

If 50.0 mL of a 0.10 M solution of sodium chloride is mixed with 50.0 mL of 0.10 M magnesium chloride, what is the molar concentration of chloride in the resulting solution?

Ion-exchange resins can remove Mg²⁺ and Ca²⁺ in water (called softening) by releasing Na⁺. What would be the concentration of sodium ion in the softened water if the combined concentration of these Group 2A ions that were removed from the hard water was 0.026 M?

If 120 g of NaOH were used to prepare 500 mL of solution, what would the concentration be?

Magnesium hydroxide is insoluble. Write the net ionic equation for the reaction that takes place between a solution of magnesium chloride and a solution of sodium hydroxide.

In a demonstration of strong electrolytes, weak electrolytes, and nonelectrolytes, Professor Popsnorkle used a lightbulb apparatus that showed how much a solution conducted electricity by the brightness of the lightbulb. When pure water was tested, the bulb did not light. When some acetic acid was added to the water, the bulb burned dimly. When more acetic acid was added to the solution, the bulb burned a little more brightly. In his frustration to make the bulb shine brightly with acetic acid, Professor Popsnorkle started over by testing the beaker of the pure acetic acid. What was the result?