Lecture 2: Chemical Bonds and Acids & Bases

Question 1

Ionic Bonds

Answer 1

-Occur between metal and non-metals
-Large difference in electronegativity
-Electron is donated

Question 2

Hydrophilic

Answer 2

water loving molecules(dissolve in water)
-Polar molecules, ions

Question 3

Hydrophobic

Answer 3

water hating molecules (do not dissolve in water)
- Non-polar molecules

Question 4

What do hydrophobic molecules do in water?

Answer 4

Hydrophobic molecules aggregate together when put in water to avoid destroying the hydrogen network formed by water

Question 5

Acids

Answer 5

Donate H+ ions
-Strong acid= complete reaction

Question 6

Base

Answer 6

-Proton (H+) acceptor
-Releases OH-

Question 6

pH(potential of hydrogen)

Answer 6

Acids and bases are characterized by the number of protons they contain
-Negative log number of the protons is the pH

Question 7

What does a buffer do?

Answer 7

Makes a solution resistant to pH changes(slows change in pH)

Question 8

How to set up a buffer?

Answer 8

-Half-equivalence point(50% acid, 50% base)
-Add more H+, they will react with CH3COO- creating CH3COOH(decrease in pH)
-Add more OH-, they will react with CH3COOH creating CH3COO-(increasing pH)

Question 9

Hydrophobic interactions(2 types)

Answer 9

1. Hydrophobic interactions: hydrophobic molecules tend to aggregate together in aqueous environments
2. Van Der Waals Forces: Non-polar molecules are attracted to each other due to transient dipoles

Question 10

What is a transient dipole?

Answer 10

-When electrons are in random locations in their orbitals causing negative side to attract positive side of another atom

Question 11

Ionic bonds within proteins

Answer 11

Ionic bonds within proteins are relatively weak

Question 12

What type of acid is most important in biology?

Answer 12

Weak acids

Question 13

Equal volumes of watery solutions and identical pH
a. contain same amount of H+ ions
b. contain the same number of water molecules
c. contain the same number of ions
d. contain solutes of the same weight
e. A and B

Answer 13

A
Watery solutions of identical pH and volume contain the same number of H , but not necessarily the same number of water molecules. That’s because solutions can contain widely different amounts of solutes, which in turn determines the number of water molecules (if there are more solutes, there will be less water molecules