Exam 21: The Main Group Elements: Life and the Periodic Table

Chromium is an ultratrace metal in the human body. The typical concentration is 5.0 mg in 70.0 kg of body mass. This concentration can be expressed as ________

Hearing aid batteries utilize a zinc/air electrochemical cell. The reduction half-reactions and standard reduction potentials for this cell are given below. Identify the oxidizing agent and the reducing agent in this cell. 1.249 V 0.401 V

Chromium is an ultratrace metal in the human body with a typical concentration of 5.0 mg in 75 kg of body mass. What is this concentration in units of parts per billion (ppb)?

The concentration of chloride in the human body is approximately 19 mg/g of body mass. What is this concentration in ppb (parts per billion)?

Iodine's role is very specific. It is incorporated into a hormone, ________, that regulates energy production and use.

Barium is a nonessential element in the human body, but some organisms build exoskeletons using barium sulfate, which has a K_sp of 1.1  10^10 at 25C. What is the mass of barium in 1.0 L of a saturated solution of barium sulfate at 25C?

Adding fluoride ions to toothpaste and drinking water to prevent tooth decay is effective because fluoride ________

Plants convert nitrogen into ammonia. This biological nitrogen fixation is affected by enzymes called nitrogenases. The enzymes assist in the transfer of electrons. The unbalanced reaction equation is What is the stoichiometric coefficient for H^ in the balanced reaction equation?

Thallium-201 is used in cardiac imaging. It decays by electron capture. What isotope is produced when thallium-201 captures an electron?

Nickel-cadmium batteries thrown into landfills can introduce cadmium ions into the groundwater. Cadmium ions can replace ________ in bones, which can weaken them.

Which anion is most abundant in the human body?

Which element, by the number of atoms, is most abundant in the human body?

What is the dominant role played by iodine in the body?

The essential elements found in the human body are classified as major, trace, and ultratrace based on their concentration levels. What are the concentration ranges that define each of these classifications?

Enzymes in plants convert nitrate into ammonia. The unbalanced half-reaction equation is given below. What is the change in oxidation number of nitrogen in this reaction?

Plants convert nitrogen into ammonia. This biological nitrogen fixation is effected by enzymes called nitrogenases. The enzymes assist in the transfer of electrons. The unbalanced reaction equation is What is the change in the oxidation number of nitrogen in this reaction?

The release of radioactive cesium-137 into the environment by the nuclear accident at Chernobyl produced a health hazard because cesium ions can substitute for ________ in plants, making them unsafe for human consumption.

Tooth enamel is composed of the mineral hydroxyapatite. It is essentially insoluble in water with K_sp  2.3  10^59, but it reacts with weak acids in the mouth as described by one of the reaction equations below. You can determine the equilibrium constant, K, for this reaction from K_sp and K_w (the equilibrium constant for water autoionization, K_w  1.0  10^14). What is the value of K?

What is the dominant role played by calcium in the body?

Plants convert nitrogen into ammonia. This biological nitrogen fixation is effected by enzymes called nitrogenases. The enzymes assist in the transfer of electrons. The unbalanced reaction equation is What is the stoichiometric coefficient for the electrons in the balanced reaction equation?