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Flashcards in Ch. 3 Deck (51)
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1

What is the measure of disorder in a system called?

Entropy

2

Which of the following represents energy in its most disordered form?

Heat energy

3

Because they generate order (by surviving, growing and forming complex communities), living cells defy the second law of thermodynamics.

False

4

Which of the following does NOT follow the first law of thermodynamics?

The use of heat to burn foodstuff inside cells

5

What is the origin of the energy that animals acquire by eating plants or other animals?

Sunlight

6

Which energy conversion characterizes photosynthesis?

Electromagnetic (light) energy → chemical bond energy

7

In both plants and animals, the process of “controlled burning” that extracts energy from food molecules is a process of gradual:

oxidation.

8

Which of the following does not describe oxidation?

The conversion of a chlorine atom to Cl-

9

Which of the following does describe oxidation?

The addition of oxygen atoms to a molecule and The removal of electrons from a molecule

10

Which of the following statements is NOT true?

Hydrogenation reactions are oxidations, and dehydrogenation reactions are reductions.

11

Which of the following statements IS true?

-Oxidation and reduction reactions always occur simultaneously.
-When a sugar molecule is oxidized to CO2 and H2O, O2 molecules are reduced.

12

Chemical reactions proceed spontaneously only in the direction that:

leads to a loss of free energy.

13

In thermodynamics, what does the term “free energy” refer to?

Energy that can be harnessed to do work or drive chemical reactions

14

Which statement about enzymes is NOT true?

Enzymes can force reactions to occur that are overall energetically unfavorable.

15

Which statement about enzymes IS true?

-Enzymes can speed up energetically favorable reactions.
- Enzymes can help build highly ordered structures.

16

What is the term for the extra energy boost required to initiate an energetically favorable reaction?

Activation energy

17

An enzyme can lower the activation energy of a reaction.

TRUE

18

.After an enzyme catalyzes a reaction, the enzyme has been consumed and cannot perform additional reactions.

FALSE

19

A reaction occurs spontaneously only if the change in free energy (/δ∊λταG) is:

negative.

20

Energetically favorable reactions are those that create disorder by decreasing the free energy of the system to which they belong.

True

21

Which of the following results in increased disorder?

Dissolving salt in water

22

nergetically unfavorable reactions can occur if they are coupled to a second reaction with a negative /δ∊λτα Gso large that the net /δ∊λτα Gof the entire process is negative.

True

23

Which is NOT true of a reaction at chemical equilibrium?

Both the forward and reverse reactions have completely stopped.

24

Which IS true of a reaction at chemical equilibrium?

-/delta G is equal to zero.
-The rates of the forward and reverse reactions are equal.

25

The free energy change (/δ∊λτα G) and the standard-free energy change(/δ∊λτα G°) of a reaction differ in that /δ∊λταG depends on the concentrations of the molecules in the reaction, whereas for /δ∊λτα G°, the concentrations are set to a fixed value.

true

26

For the simple reaction Y → X, the equilibrium constant K is:

[X]/[Y]

27

For every 1.42 kcal/mole difference in free energy at 37°C, K changes by a factor of:

10

28

Consider the reaction A + B → AB. How is the equilibrium constant expressed for this reaction with two substrates and a single product?

K = [AB]/[A][B]

29

Two molecules will bind to each other by means of noncovalent bonds if the /δ∊λτα Γ° of the interaction is:

negative (the free energy of the product is lower than the sum of the free energies of the unbound partners).

30

Consider two molecules that associate with each other through hydrogen bonds. The larger the equilibrium constant, K, for this association:

the more tightly the two molecules will bind.