Question

Which of the following are processes that decrease entropy? (select all that aply)

Answers

Pb2+(aq)+S2?(aq)?PbS(s)

NaCl(s)?Na+(aq)+Cl?(aq)

Ca2+(aq)+CO2?3(aq)?CaCO3(s)

CaO(s)+CO2(g)?CaCO3(s)

1) Suppose the reaction A?B has a small positive ?G?. The reaction would proceed _______, and when equilibrium is reached, _______ would be present.

Answers

From A to B; a large excess of B over A

From B to A; a small excess of B over A

From A to B; a large excess of A over B

From B to A; a small excess of A over B

2) Suppose a carbohydrate polymer does not fold spontaneously in a living cell. Which of the following can be said of the carbohydrate polymer folding?

Answers

The free energy change is greater than zero.

The free energy change is less than zero.

The entropy change is less than zero.

The enthalpy change is greater than zero.

3) The combustion reaction of methane is shown by the chemical equation below, which can be used to predict whether the change in entropy is positive or negative. At what temperatures is this reaction expected to be spontaneous?

2CH3OH(g)+3O2(g)?2CO2(g)+4H2O(g)

Answers

Not spontaneous at any temperatures

Spontaneous at all temperatures

Spontaneous at high temperatures

Spontaneous at low temperatures

Answer 1

A) decrease entropy reactions

Pb2+(aq)+S2?(aq)---------------> PbS(s)

Ca2+(aq)+CO2?3(aq)-------------->CaCO3(s)

CaO(s)+CO2(g)------------------>CaCO3(s)

these three are precipitation reactions so entropy decreases

1)

answer : From B to A; a small excess of B over A

2)

answer : The free energy change is greater than zero.

3)

answer : Spontaneous at all temperatures

reason is that DH is negative for combustion reaction and DS is positve so DG always negative so Spontaneous at all temperatures