Intro and chemical bonds

Question 1

Equal volumes of watery solutions with same pH contain the same amount of

Answer 1

Protons

Question 2

Rank the forces in order of strength:
hydrophobic interactions, H-bonds, covalent bonds

Answer 2

Covalent, H-bonds, hydrophobic

Question 3

What is the mass number of an atom?

Answer 3

number of protons + neutron

Question 4

What are isotopes and what is a main example?

Answer 4

Elements with same number of protons but different amount of neutrons. Mains example is carbon 14 as it allows for dating of objects (long decay period)

Question 5

What are the main properties of water?

Answer 5

Adhesion, Cohesion, higher density as fluid, surface tension, high specific heat capacity, ice forms crytal latice, water doesn’t

Question 6

What are the Van der Waals interactions?

Answer 6

Small attarctive forces that occur due to fluctuation of charges

Question 7

What is the definition of an acid?

Answer 7

Releases/donates H+ ions (proton)

Question 8

What is the difference between a strong and a weak acid?

Answer 8

A strong acid fully dissociates while a weak acid only dissocaites partially and reversibly

Question 9

What is the definition of a base?

Answer 9

They accept H+ (realease OH-)

Question 10

What is an example of an important acidic group? of a basic group?

Answer 10

-COOH (carboxyl) for the acid and -NH2 (amino) for the base

Question 11

How does titration work?

Answer 11

We add a strong base into a solution with a weak acid to see the increase of pH. The pH is expected to increase dramatically btu due to the presence of the undissociated acid molecules the increase is slow. As well, adding an acid would decrease the pH slowly because the added protons would reform the undissociated form of the weak acid. Principle behind buffers

Question 12

How can a buffer for both acid and base be made? Why is this the case?

Answer 12

If you want to make a buffer that buffers in both directions, you have to add
equal amounts of weak acid and its conjugate base to reach the half-
equivalence point of the titration curve. Becauase As can be seen
from the titration curve, a weak acid on its own can only buffer added base (and vice-verza)

Question 13

What is the buffering range?

Answer 13

Range at which the buffer is able to effectively maintain the pH at equilibrium

Question 14

Why are buffers important?

Answer 14

In many species, buffers can be found (like in blood) to maintaint the homeostasis of the individual

Question 15

What else can you read off from a titration curve?

Answer 15

The protonation state,
e.g. at pH7, the COOH group discussed here will largely be COO-

Question 16

Why is carbon a very important element?

Answer 16

It can form 4 cvalent bonds which can create an infinity of sturcutres

Question 17

What are the main functional groups? What are their function?

Answer 17

Hydroxyl (-OH, polar, weak acid), Phospate (breaking O-P bonds releases a lot of energy), Sulfhydryle (SH, can from S-S bonds that stabilize proteins), Carbonyls( C=O, reacts with other elements), Carboxyl (COOH, acts as an acid)

Question 18

What is biochemical unity and what is an advantage of it?

Answer 18

All biological organisms are made up of the same componentes. This is advantageous as all living organsism can feed of of one another to gain energy from digestion

Question 19

What are the two main reactions in metabolism?

Answer 19

Condensation: release of one water molecule to add a monomer to form polymers (anabolic)
Hydrolysis: Breaking of covalent bond by addition of a water molecule (catabolic)

Question 20

Chem vs Bio bond formation or breaking. Which one requires energy and which one releases energy.

Answer 20

Keep in mind that breaking a single covalent bond requires energy, whereas
forming a single covalent bond releases energy. When a biology textbook
talks about ATP hydrolysis releasing energy or breaking a starch polymer
into monomers releasing energy, they mean the entire chemical reaction,
which involves at least 2 covalent bonds being broken and 2 covalent bonds
being formed.