Ch. 2.2 - Acids and Bases

Question 1

dissociation of water molecules and ph (4)

Answer 1

• water can dissociate into H+ and OH-
• this reaction is constantly occurring and is in equilibrium, so that in 1L of pure water there are 1.0x10^-7 moles of H+ and equal OH-
• both are highly reactive
• we use pH to quantify how much H+ there is available for reactions

Question 2

acids and bases (2)

Answer 2

• acids donate H+ in aqueous solutions

- bases donate OH- or accept H+

Question 3

pH scale (5)

Answer 3

-pH describes how acidic or basic a solution is
-it’s the negative log10 of the hydrogen ion concentration
>pure water H+ concentration is 1x10^-7 moles, pH 7
-pH 6 = 10x more acidic (H+) than 7
-every change in pH of 1 unit represents a 10 fold increase in the H+ of a solution

Question 4

life and pH (3)

Answer 4

• the molecules and chemistry of life function within very narrow ranges of pH
• pH of blood plasma=7.35-7.45 if it goes as low as 6.8 or high as 7.8 you die
• pH of 7 is 4x more acidic than a pH of 7.4

Question 5

pH and buffers (4)

Answer 5

• buffers are solutions that resist change in pH when acid or bases are added to them
• if we added a small amount of a strong acid to 1L of pure water, the pH may drop from 7 to 2 (a 100k fold difference in H+)
• if we did the same to 1L of blood plasma, the pH would only drop from 7.4 to 7.3 (a doubling of H+)
• a buffer is a solution if a weak acid and its associated weak base

Question 6

bicarbonate buffer

Answer 6

CO2 + H2O H2CO3 H+ + HCO3 2H+ + CO3(-2)

Question 7

acid rain (deposition)

Answer 7

• pH of normal rain: 5.6

- pH of acid rain <5.2 often 4.2-4.4

Question 8

where does acid precipitation effect the most? (3)

Answer 8

streams, wetlands, and lakes

Question 9

acidic water running off of soil carries what?

Answer 9

dissolved elements, such as aluminum, in toxic levels

Question 10

what happens when water becomes too acidic?

Answer 10

reduces carbonate ions in water which means skeletons or shells cannot be produced

Question 11

acid precipitation effects on trees

Answer 11

when toxins are leached from soil, robs soil of essential nutrients and reduces the tolerance of plants and trees to other environmental stressors (extreme temp changes, insects and disease)