Cellular pH*All matter has the ability to be dissolved

into a solution. A solution is a type of liquid mixture in which a solid is dissolved into a liquid.

*Two parts two a solution:

Solvent – the liquid part of a mixture that does the dissolving.

Solute – solid substance being dissolved into a solution.

Example Solutions:salt water, blood, Sprite, coke

*Water is the most common solvent in solutions.

*The most important chemical property of a solution is its pH.

pH – is the measure of how acidic or how basic a solution is.

*pH is an abbreviation for “potential hydrogen”, which is created when water breaks down matter in a solution.

How does water determine the pH of a solution?

*When water dissolves matter into a solution, water actually dissociates (breaks apart) into ions instead of individual hydrogen and oxygen atoms. An ion is one or more elements that are charged due to the gain or loss of electrons.

*Water breaks down into TWO types of ions:

H2O > H+ + OH-

*H+ ion called hydronium ion and an OH- ion called hydroxide ion.

*As long as water is pure and nothing is being dissolved, both of these ions will be present in EQUAL amounts. Water is said to be neutral. A neutral solution is described as any substance that contains an equal amount of H+ and OH- ions in solution.

*However, if any other matter is present and is dissolved into a solution by water, an UNEQUAL number of these ions are formed.

*The pH of a solution is a measure of the H+ as water breaks matter down. If there is an imbalance of ions, the solution is either acidic or basic (alkaline).

Acid – any type of solution that contains a greater concentration of H+ ions than OH- ions.

Base – any type of solution that contains a greater concentration of OH- ions than H+.

*Not all acids and bases are created equal; some are stronger and destructive; others are weak and harmless.

*The balance of the two ions from water (H+ and OH-) determine just how strong an acid / base is and is represented by a pH number arranged on a pH scale.

The “Rule of Thumb” for acid and base strength is this….(meaning, you better know this!!!!!)

The greater the concentration of the ion that makes the acid or base, the stronger the acid or

base is.

*The closer the ions are to becoming balanced, the weaker the acid and base.

*In other words, stronger acids have more H+ than OH-; stronger bases have more OH- than H+.

Characteristics of Acids and BasesAcids

*0 – 6.9 on pH scale.*naturally sour in taste.*good conductors of

electricity (used in car batteries)

*H+ > OH-*Stronger acids have

lower pH numbers; weaker acids have higher pH numbers.

Bases

*7.1 – 14 on pH scale.

*naturally slimy in texture.

*good conductors of electricity (used in alkaline batteries)

*OH- > H+*Stronger bases

have higher pH numbers; weaker bases have lower pH numbers.

The pH Scale

Weak Acids:(pH 5 – 6)

*Acid Rain

Medium Acids:(pH 3 – 4)

*Vinegar*Colas*Citrus Fruits

Strong Acids:(pH 0 – 2)

*Toilet Bowl Cleaner*Rust Remover*Stomach Juices*Battery Acid

Weak Bases:(pH 8 – 9)

*Shampoos*Body soaps

Medium Bases:(pH 10 – 12)

*Heartburn Medication (antacids)

*Cleaners*Detergents

Strong Bases:(pH 13 – 14)

*Ammonia*Drain Cleaners*Alkaline Batteries

*Acids and bases can only be compared to each another as “equals but opposites”…..one is no more stronger or more dangerous than the other.

*The strength of one acid can only be compared to another acid…not to a base (and vice-versa).

*For each increase or decrease in pH number on the pH scale, the strength of an acid (or a base) will change by the power of 10.

*For example, a base with pH = 11 is 10x stronger than pH = 10, 100x stronger than pH = 9 , and 1000x stronger than pH = 8.

*An acid with a pH of 5 is 10x weaker than a pH of 4; 10,000 times weaker than pH of 1!!!

*General Formula To Determine Comparison Strengths:

10n

(where n = # of spaces between two solutions on pH scale)

Example Problems

1) In a chemistry experiment, Bertha’s solution had a pH of 1; Agatha’s solution had a pH of 6? What is the comparative strength of these two acids?

There are FIVE spaces between 1 and 6 on pH scale; therefore

use “105” power.

Final Answer: pH 1 is 100,000x STRONGER than pH 6.

2) Clifford tested his soil in his garden and he determined that the soil pH level was 10. Corn prefers a neutral soil level.

a. In terms of pH, what type of soil is Clifford’s corn growing in?

Medium basic soil

b. How strong is a soil pH of 10 compared to 7?

103 = 1000x stronger

Neutralization*Since acids and bases are “equals, but

opposites”, one has the capacity of neutralizing the other.

Neutralization – the process of adding an acid or base to a solution to achieve a pH of 7.

*Only acids can neutralize bases; only bases can neutralize acids.

*Each acid has an opposite base (called a “conjugate base”) on the pH scale that is equal in strength; each base has an opposite acid (called a “conjugate acid”) on the pH scale that is equal in strength.

*Each acid or base conjugate is the direct opposite (mirror image on the pH scale) pH number.

*Ex: A base w/ pH of 9 will need a conjugate acid w/pH of 5 to neutralize it and bring the pH down to 7.

Why?

Both pH of 9 and pH of 5 are equally distance from pH of 7 on pH scale.

Example Problems1) Sally’s swimming pool has

a pH of 11. What type of solution and its pH would Sally have to add to bring her pool water back to a safe pH of 7?

Since pH of 11 is a base, Sally would have to add a conjugate acid of 3 to neutralize her pool (both are four units away from pH of 7 on pH scale).

2) Billy Bob has severe heartburn, with an estimated pH of 1. Which of the following antacids would be the most effective at neutralizing his heartburn? Which would be the least effective?

Rolaids: pH = 10Alka Selzter: pH = 8

Citricil: pH = 6Tagamet: pH = 13

Answer: Most Effective = Tagamet

Least Effective = Citricil (its an acid!!)

pH Indicators*You cannot tell the pH of a

solution just by looking at it.

*It is possible to determine a solution’s pH by the use of a pH indicator.

Indicator – a chemical that turns a specific color in the presence of an acid, base, or neutral solution.

Types of pH Indicators

Red LitmusBlue Litmus

PhenylphthaleinWide Range pH Indicator

Red Cabbage (natural indicator)

. Enzyme Activity*All living things are driven by

chemical reactions respiration, digestion, cell division, glycolysis, protein production are just a few of thousands of chemical reactions that occur within you right at this moment.

*Unfortunately, the natural rates of chemical reactions within our body are sooooo slooooow that they cannot sustain life.

*All chemical reactions must require “help” because the amount of energy needed to get them started (called activation energy) is too high.

How do these chemical reactions take place within us if they are so slow?

*A catalyst is any type of substance (natural or man-made) that lowers the amount of activation energy needed to start a chemical reaction.

*Catalysts speed up chemical reactions thousands of times faster than those without catalysts; they do NOT increase the amount or the quality of product made at the end of the reaction!!

*Special types of proteins called enzymes are the catalysts used in living things.

Enyzme – a type of biological catalyst that is used to speed up chemical reactions in living things.

*Enzymes speed up chemical reactions such as respiration, cell division, and digestion by lowering the amount of activation energy needed to get the reaction going.

Energy Diagram

*Enzyme Benefits:

1) Chemical reaction proceeds faster.2) Enzyme is reusable..... once the enzyme speeds up reaction, it is NOT used up in the process.

*Enzyme Cons:

1) Essential for life; many illnesses and genetic disorders are the result of missing or malfunctioning enzymes.2) Enyzmes are picky..... meaning that each type of enzyme can work only on certain reactions; they are NOT universal.

*The reactant or ingredient that an enzyme works on in a chemical reaction is called a substrate.

*To speed up the chemical reaction, the enzyme binds to the substrate at its active site.

*Because enzymes are picky as to which substrate it will work on, the active site is shaped to fit the specific enzyme. This prevents other unnecessary enzymes from working on the substrate.

*Notice the enzyme is shaped to fit the substrate at the active site. This phenomenon is called the lock and key model because it describes how particular enzymes are complementary to their substrates just like keys are to a specific lock.

How Enzymes Work

*Real-life examples of enzyme-substrate complexes:

(FYI: most enzymes end in the suffix “-ase”)

Enzyme Name: Substrate: Reaction:

1) Amylase Amylose Digestion of starch

2) Helicase DNA Unwinds DNA during replication

3) Lactase Lactose Digestion of milk

sugar

4) Lipase Lipids Breakdown of fats

*Factors that affect enzyme function:

1) Temperatures – extreme temperatures will denature (alter) the shape of the enzyme, causing it not to bind properly to substrate; most human enzymes prefer temperatures between 98-99F.

2) pH Levels – most living things prefer pH levels between 6 – 8; environments that are too acidic or basic will denature the shape of enzymes.

3) Surface Area – enzymes will work faster and are more effective on substrates that are already broken into smaller pieces instead of one huge chunk; we chew are food into small pieces so that digestive enzymes can work faster at breaking the food down.

4) Concentration – the more enzymes present, the better that they will work; higher concentrations of enzymes = faster chemical reactions.