Revision Questions

Question 1

How can you speed up a chemical reaction?

Answer 1

Change temp

Lower activation barrier

Increase concentrations of reactions

Coupling reactions speeds up process more efficient this way.

Question 2

Explain function of water?

Answer 2

Water has areas of + and - can form other hydrogen bonds

Stronger due to overlapping weaker as may be interference from other atoms

• water is a good solvent for amino acids,carbon and small alcohols
• poor solvent for non polar gases, aromatic molecules and aliphatic chains (straight)

Question 3

What is water good at dissolving?what is water not good at dissolving?

Answer 3

GOOD - Amino acids, carbohydrates, small alcohols

BAD - non polar gasses, aromatic molecules, aliphatic chains

Question 4

How can the rate of a chemical reaction be sped up?

Answer 4

Lower activation barriers, change temps

Question 5

Why are hydrogen bonds important?

Answer 5

Hydrogen bonding is responsible for waters unique solvent capabilities,

hydrogen bonds hold complimentary strands of DNA together responsible for determining structure of folded proteins (enzyme antibodies)

Question 6

What other times of bonds are there?

Answer 6

Hydrogen
Covalent
Zwitterion

Question 7

What is a non-polar molecule?

Answer 7

A nonpolar molecule contains non polar bonds CI-CI-H-H

OR has a symmetrical arrangements of polar bonds O=C=O

Question 8

What is the formula of PH? What is the formula for pKa?

Answer 8

PH=-LOG [H+]

PKa=- LOG 10 (K)

Question 9

What is a chiral centre ?

Answer 9

Chiral molecules usually contain at least one carbon atom

Atom with four non identical substitutes, such as a carbon atom is called a chiral centre

Question 10

How do catalysts work?

Answer 10

A catalyst can increase the rate of reaction.

The catalyst remains unchanged at the end of the reaction catalyst

A catalyst works by providing an alternative reaction pathway to the reaction product.

Rate of reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst

Question 11

Name two categories of stereoisomer?

Answer 11

GEOMETRIC

OPTICAL

Question 12

State the name and specific type of bond in alkenes ?

Answer 12

Double bond or pie bond

Question 13

Which type of stereoisomer would amino acids form?

Answer 13

Optical stereoisomer

Question 14

Which type of stereoisomer would alkenes form ?

Answer 14

Geometric

Restricted can’t twist due to double bonds

Question 15

What is the functional group of the alkenes that allows them to form isomers?

Answer 15

Alkene has double bonds C=C won’t rotate takes to much energy to break. This allows them to form isomers

Question 16

Give an example of a CIS and trans isomer of an alkene?

Answer 16

CH3      CH3
   \             /
       C=C 
    /.        \
  H.       H. 
      CIS

H. CH3
\ C=C /
CH3. H

TRANS

Question 17

What kind of bond that joins the amino acids together?

Answer 17

Peptide bond

Question 18

Work out the PHs of. 0.200 mol dm3 hydrochloride acid?

Answer 18

-LOG H+ = 3.69

Question 19

Define PKa ?

Answer 19

-LOG - [ka]

Question 20

The value for Ka for ethanoic acid is 1.74 x 10 -5 mol dm-3 (to significant figures) what is the value of PKa ?

Answer 20

-LOG (1.74 x 10-5) = 4.75

Question 21

Work out acid A: 6.32 x 10 -5 mol dm3 ?

Answer 21

• LOG - [KA] ( 6.32 x 10 -5) = 1.76

Question 22

Work out ka of acid B: 150 x 10-4 mol dm3?

Answer 22

• LOG [KA] (1.50 x 10-4)=1.04