Chemistry 1050 final chapter 6

Rusting chemical equation

4Fe(s) + 3O2(g) ---> 2Fe2O3(s)

Acid

At the molecular level, an acid is a compound that releases hydrogen ions, H+, in aqueous solutions. sour taste (lemons, vinegar) (1-6.9 on pH scale)

Automobiles and SOx and NOx

Automobiles produce NOx but very little SOx

How can seawater be basic?

Ocean water contains small amounts of 3 chemical species that play a role in maintaining the ocean pH at approx. 8.2: the carbonate ion, the bicarbonate ion, and carbonic acid. These species also help maintain your blood at a pH of about 7.4

Ocean acidification

The lowering of the ocean pH due to increased atmospheric carbon dioxide The H+ produced by the dissociation of carbonic acid reacts with carbonate ion in seawater to form the bicarbonate ion H+(aq) + CO2,3(aq) ---> HCO3-(aq)

denitrification

The process of converting nitrates to nitrogen gas. The bacteria harness the energy released in forming the triple bond found in the nitrogen molecule. NO3 --> NO --> N2O --> N2 bacteria in the soil

Why are mountaintops more susceptible than grassy plains to acid deposition?

They contact clouds with more concentrated acid droplets

Strong acid

an acid that dissociates completely in aqueous solution. Hydrochloric acid (HCl)

acid deposition

both wet and dry forms of delivery of acids from the atmosphere to the surface of Earth.

What negative effects of acid rain affect cars and trucks?

damage to paint and finish and increased susceptibility to rust

"Normal Rain"

found slightly acidic, with a pH in between 5 and 6. Even though the acid formed by dissolved carbon dioxide is a weak acid, enough H+ is produced to lower the pH of the rain. Seawater is slightly basic with a pH of approx. 8.2

Gases that dissolve in water to produce an acidic solution

hydrochloric acid, sulfur dioxide, and nitrogen dioxide

Some lakes recover relatively quickly once SO2 emissions are reduced. The most likely explanation for this recovery is that these lakes are in regions where..

limestone rock naturally neutralizes the area

Neutral Solution

neither acidic or basic, that is, it has equal concentrations of H+ and OH-. Pure water is a neutral solution. Some salt solutions are neutral, such as the one formed by dissolving solid NaCl in water.

How did the connection between food production and NOx emissions arise

nitrates act as fertilizers and promote plant growth.

Which anthropogenic pollutants are implicated in the formation of most acidic precipitation?

nitrogen oxides and sulfur oxides

Acid rain

rain with a pH below 5.

wet deposition

rain, snow, fog results from direct contact with clouds containing microscopic water droplets. Because the droplets contain acids that are more concentrated than those found in larger raindrops, they are often more acidic and damaging than acid rain.

nitrogen-fixing bacteria

remove nitrogen gas from the air and convert it to ammonia. N2 --> NH3 --> NH4+ nitrogen h2o fixation

acid-neutralizing capacicty

the capacity of a lake or other body of water to resist a decrease in pH

reactive nitrogen

the compounds of nitrogen that cycle through the biosphere and interconvert with each other.

NO2 most significant reaction

the one that converts it to nitric acid, HNO3 NO2(g) + OH(g) ---> HNO3(aq) HNO3 is a strong acid that dissociates completely in water to release aqueous H+ and NO3-

Nitrification

the process of converting ammonia in the soil to the nitrate ion NH4+ --> NO2 -->NO3- bacteria in the soil

dry deposition

"dry" forms of acids that deposit on land and water. during dry weather, tiny solid particles (aerosols) of the compounds ammonium nitrate and ammonium sulfate are deposited

Ammonia

Ammonia molecules remove protons from water molecules, forming hydroxide ions. When an ammonia molecule reacts with a water molecule, the water molecule transfers H+ to the NH3 molecule. An ammonium ion, NH4+ (aq) and a hydroxide ion, OH- are formed. NH3(aq) + H2O(l) ----> NH4+(aq) + OH-(aq) however, this reaction only occurs to a small extent so only a tiny amount of OH-(aq) is produced. Aqueous ammonia is an example of a weak base

Strong Bases

Bases that dissociate completely in water, such as NaOH

How does the sulfur content of coal contribute to acid rain?

Burning coal produces sulfur dioxide in varying amounts. When coal is burned, the sulfur dioxide produces goes up in the smokestack along with the carbon dioxide, water vapor, and small amounts of metal oxide ash. Once in the atmosphere, SO2 can react with oxygen to form sulfur trioxide (SO3). Once SO3 is formed, it reacts rapidly with the water vapor in the atmosphere to form sulfuric acid.

which reaction accounts for the fact that the pH of rain is naturally slightly acidic?

CO2 + H2O ---> H+ HCO3-

CO2 in aqueous solutions

CO2 is far less soluble in water than SO2 and NO2. Even so, it dissolves to produce a weakly acidic solution When CO2 dissolves in water, it produces carbonic acid H2CO3 CO2(aq) +H2O(l) --> H2CO3(aq) the carbonic acid dissociates to produce H+ and the hydrogen carbonate ion.

NOx, NO, & N2

NOx emissions are a form of reactive nitrogen and they increase the acidity of the precipitation from the sky. NO is formed from unreactive N2 in the air when fuels are burned. The more fuels are burned, the more N2 is changed into a reactive form.

Which chemical equation shows the dissociation of 2 protons from trihydrogen phosphate

H3PO4 ---> 2H+ + HPO2,4

Hydrochloric acid

HCl (aq) + H2O (l) --> H3O+(aq) + Cl-(aq) the solution represented on the product side is called hydrochloric acid. It has the characteristic properties of an a cid because of the presence of H3O

What is the final step in the formation of acidic aerosol?

Reaction of sulfur trioxide with water.

In the early 1990s, glass manufacturers developed a green chemistry solution to reducing NO emissions and energy consumption. This involved..

Substituting 100% oxygen for air in the large furnaces used to melt and reheat the glass

The relationship between the concentration of hydrogen ion and hydroxide ion in any aqueous solution

[H+][OH-] = 1x10^-14 ex: if a rain sample has a H+ concentration of 1x10^-5 M, we can calculate the OH- concentration: (1x10^-5) x [OH-] = 10^-14 [OH-] = 10^-9 If the hydroxide ion concentration is smaller than the hydrogen ion concentration, the solution is acidic

Neutralization reaction

a chemical reaction in which the hydrogen ions from an acid combine with the hydroxide ions from a base to form water molecules. HCl(aq) + NaOH(aq) ---> NaCl(aq) + H2O(l)

Base

a compound that released hydroxide ions, OH-, in aqueous solution. (usually taste bitter and have a slippery, soapy feel) ex: household ammonia (an aqueous solution of NH3, and NaOH, sometimes called lye)

Which substance has the highest pH?

a lye solution

pH

a number between 0 and 14 that indicates the acidity or basicity of a solution. pH 7 separates acidic from basic solutions. pH less than 7 is acidic and pH greater than 7 is basic. pH 7 is neutral (pure water).

nitrogen cycle

a set of chemical pathways whereby nitrogen moves through the biosphere.