Category: Chemistry homework help

hemoglobin and myoglobin

Carbon monoxide binds tightly to the heme groups of hemoglobin and myoglobin. How does this affinity reflect the toxicity of carbon monoxide?

A. Since carbon monoxide binds the heme groups of hemoglobin, it is easily removed or replaced by oxygen. As a result, the effects of oxygen enhancement result in what divers call the “bends.”

B. Because carbon monoxide binds the heme groups of hemoglobin, it is easily removed or replaced by oxygen. As a result, the effects of oxygen deprivation result in suffocation.

C. Because carbon monoxide binds tightly to the heme groups of hemoglobin, it is not easily removed or replaced by oxygen. As a result, the effects of oxygen deprivation result in suffocation.

D. None of the above

glycogen metabolism

What effect does glycogen metabolism have on glucose levels?

A. Glycogen metabolism traps glucose within liver cells and increases storage of glucose in the form of glycogen. These processes decrease blood glucose levels.

B. Glycogen metabolism traps glucose within liver cells and increases storage of glucose in the form of glycogen. These processes increase blood glucose levels.

C. Glycogen metabolism releases glucose within liver cells and increases storage of glucose in the form of glycogen. These processes decrease blood glucose levels.

D. None of the above

function of gluconeogenesis

What is the physiological function of gluconeogenesis?

A. Gluconeogenesis is production of glucose from noncarbohydrate molecules in times when blood glucose levels are low. This ensures proper function of brain and red blood cells, which only use glucose as fuel.

B. Gluconeogenesis is production of glucose from noncarbohydrate molecules in times when blood glucose levels are high. This ensures proper function of brain and white blood cells, which only use glucose as fuel.

C. Gluconeogenesis is production of glucose from carbohydrate molecules in times when blood glucose levels are low. This ensures proper function of brain and red blood cells, which only use glucose as fuel.

D. None of the above

 

an atom loses electrons

17 Tro: Chemistry: A Molecular Approach, 2/e

CH4 + 2 O2 → CO2 + 2 H2O −4 +1 0 +4 –2 +1 −2

oxidation

reduction

Oxidation–Reduction • Oxidation and reduction must occur simultaneously

• if an atom loses electrons another atom must take them • The reactant that reduces an element in another

reactant is called the reducing agent • the reducing agent contains the element that is oxidized

• The reactant that oxidizes an element in another reactant is called the oxidizing agent

• the oxidizing agent contains the element that is reduced

2 Na(s) + Cl2(g) → 2 Na+Cl–(s) Na is oxidized, Cl is reduced

Na is the reducing agent, Cl2 is the oxidizing agent

Oxidation and Reduction

Reaction coordinate

Gi

Gf ∆G < 0, spontaneous

Gf ∆G =0 equilibrium

Oxidation–Reduction • Reactions where electrons are transferred from one

atom to another are called oxidation–reduction reactions

• redox reactions for short • Atoms that lose electrons are being oxidized, atoms that

gain electrons are being reduced

2 Na(s) + Cl2(g) → 2 Na+Cl–(s) Na → Na+ + 1 e– oxidation Cl2 + 2 e– → 2 Cl– reduction16

Tro: Chemistry: A Molecular Approach, 2/e

Oxidation and Reduction • Oxidation occurs when an atom’s oxidation state

increases during a reaction • Reduction occurs when an atom’s oxidation state

decreases during a reaction

e liquid-liquid coexistence curve

Problem 5(20 points) Consider the liquid-liquid coexistence curve of two species A and B.

The mole fractions of A in the upper (xu) and lower (xl) phases within the two phase region are

given by:

T/K 309.820 309.432 309.031 308.006 306.686

xl 0.473 0.400 0.371 0.326 0.293

xu 0.529 0.601 0.625 0.657 0.690

T/K 304.553 301.803 299.097 296.000 294.534

xl 0.255 0.218 0.193 0.168 0.157

xu 0.724 0.758 0.783 0.804 0.814

(1)

(A) Plot the phase diagram. (B) Suppose you form a mixture with 2 moles of A and 1 mole of

B at T = 299.1 K. How much of the upper and lower phases do you have? To what temperature

must the mixture be heated to form a single-phase? (C) If A and B can be treated as forming a

regular solution, please determine ξ as a function of temperature. Plot your results.

3

Consider a sealed container filled with 0.7 moles of H2(g)

Quesiton 4: (20 points) Consider a sealed container filled with 0.7 moles of H2(g), 0.9 moles of

trans-2 butene C4H8(g) and 0.4 moles of butane (C4H10(g)) at 400K. The initial total pressure in

the container is 2 bar. Calculate the amounts of each component in the mixture at equilibrium for

the reaction H2(g)+C4H8(g) ⇀↽ C4H10(g). You may not assume that the entropies and enthalpies

are temperature independent (but you can assume Cp’s are temperature independent). You may

treat the gases ideally. Also please calculate ∆G for going to equilibrium.

2

(B) Once the system reached equilibrium, assume you squeezed on the container and reduced

the volume by a factor of 30. Calculate the the new composition of molecules in your container,

and ∆G for this process of squeezing the equilibrium state in (A) to go to a new equilibrium state.

composition phase diagram for two substances

Question 3: (10 Points) Consider the T vs. composition phase diagram for two substances,

A and B, that behave ideally. Please explain why in the T vs. composition phase diagrams you

do not observe boiling point elevation for both components A and B when they mix (and that

only one of them experiences boiling point elevation (which one?)). Hint: since these are ideal

solutions, it cannot be due to interactions. Equations are welcome but not necessarily required.