A Unique Insect - Pheropsophus Verticalis the Bombardier Beetle Is a Small Insect Whose

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A Unique Insect - Pheropsophus verticalis The bombardier beetle is a small insect whose habitat is under rocks that are found in the moist flood plains of rivers, lakes, and temporary post-rainstorm ponds of southern Canada, the United States, and Australia. This unique insect defends itself by firing a boiling hot spray from the rear of its abdomen when assaulted. This spray allows the beetle to unfurl its wings from under wing covers and fly away. The spray is formed at the moment of firing by mixing chemicals from two glands in the beetle's abdomen. The spray changes instantly into a gas and is directed away from the beetle. The gas irritates the eyes of the enemy and forms a smoke screen that helps the beetle to escape ©2000 Australian Broadcasting Corporation while the enemy is confused. Two chemicals, hydroquinone and hydrogen peroxide, collect in a reservoir that has a valve controlled opening into a thick-walled reaction chamber. The reaction chamber is lined with cells that secret peroxidases and catalases, enzymes that rapidly break down the hydrogen peroxide and hydroquinone. When the contents of the reservoir are forced into the reaction chamber through a muscle-controlled valve, a reaction quickly occurs. Hydroquinone is changed into p-quinone and the hydrogen peroxide into water and oxygen. There is enough heat generated from the reaction to bring the mixture to the boiling point and vaporize some of it creating pressure in the reaction chamber. The products of the reaction are expelled explosively through openings at the tip of the beetle's abdomen. Problem 1: Balance the equation for the reaction that occurs in the reaction chamber of the bombardier beetle. Hydroquinone + Hydrogen peroxide → p-quinone + water + oxygen

+ → + +

C6H4(OH)2 (l) + H2O2 (l) → C6H4(OH)2 (l) + H2O (l) + O2 (g)

Problem 2: If 1.00 grams of hydrogen peroxide and 2.00 grams of hydroquinone are added to the reaction chamber, which is the limiting reactant? What is the excess reactant and by how much is in excess?

Problem 3: How many grams of water can be formed if 1.00 grams of hydrogen peroxide reacts with 2.00 grams of hydroquinone in the reaction chamber, according to problem 2? Name______Date:______Period:____ Introducing the Fire Ant The red imported fire ant, Solenopsis invicta (Buren), is an introduced species that arrived in Mobile, Alabama in the soil of potted plants or on the ballasts of ships arriving from South America in the 1930s. This species has had an enormous impact in the southeastern United States, and continues to spread into areas of North America with mild climates and adequate moisture and food.

Fire ants use their stingers to immobilize or kill prey and to defend their ant mounds from disturbances. Any disturbance to the mound sends hundreds of workers out to attack anything that moves. A fire ant grabs its victim with its mandibles (mouth parts) and then inserts its stinger. As the ant stings the intruder it injects venom that causes a burning sensation and subsequent blistering (hence their name). An individual ant can sting multiple times, and sting sites may develop pustules and secondary infections.

The composition of fire ant venom is complex: 95% of the venom is composed of water insoluble piperidine alkaloids responsible for the local reaction at the sting site and the remaining 5% made up of several allergenic proteins. Formic acid is an important component of fire ant venom and the fire ants may be as dangerous as bees and wasps.

Problem 1: One of the components of fire ant toxin has the following chemical analysis, 26.09% carbon, 69.52 % oxygen, and 4.38% hydrogen. The molar mass of this substance is 46.03g/mol. Determine the empirical and molecular formula of this molecule. The eumpirical formula is the smallest whole number ratio of the moles of each element and the molecular formula is the actual number of atoms of each element in one molecule/formula unit. If the empirical molar mass is the same as the molar mass observed experimentally, so to are the empirical and molecular formulas. Elements Mass

Element Moles

Formulas

Problem 2: How many molecules of the compound referred to in problem 1 are present in an ant bite that contains 1.00 microgram of this substance?

Problem 3: Another component of fire ant venom has the following chemical composition: 70.5% carbon, 13.0% hydrogen, 16.5% nitrogen. The molar mass of this molecule is 85.14 g/mol. Determine both the empirical and molecular formula of this molecule. Elements Mass

Element Moles

Formulas

Problem 4: If each ant bite contained 0.500 micrograms of the compound determined in problem 3, how many molecules would it contain?