23 Marks: 1 What is the sign on the change in entropy for the process: 2N 2 (g)

Question

23

Marks: 1

What is the sign on the change in entropy for the process: 2N2(g) + O2(g)--> 2N2O(g)

Choose one answer.

Question 24

Marks: 1

What is the sign on the change in entropy for the process: 2N2O5(g)--> 4NO2(g) + O2(g)

Choose one answer.

Question 25

Marks: 1

What is the sign on the change in entropy for the process: Cgraphite(s) at 0oC --> Cgraphite(s) at 25oC

Choose one answer.

a. entropy is increasing b. entropy is unchanged c. entropy is decreasing d. entropy cannot be approximated

Explanation / Answer

(23)   the given equation is...

2N2(g) + O2(g)--> 2N2O(g)

By definition, entropy is a measurement of disorderness.

In solids the molecules are very very close to each other means they are much ordered. So, the entropy is least for solids.

In liquids, the molecules are somehow farther from each other means they are less ordered than solids and so their entropy is greater than solids.

For gas, the molecules are much farther from each other and so they are the most disordered and hence their entropy is highest.

in the equation equation, we have all the gases. on reactant side we have 3 molecules of gases where as on the right side we have only two molecules of gases. So, as the number of gaseous molecules is decreasing, entropy is also decreasing and decrease in entropy means negative sign.

So, the correct choice is (C), entropy decraesing. (Negative sign).

(24) The given equation is...

2N2O5(g)--> 4NO2(g) + O2(g)

here, we have 2 molecules of gases on left side and 5 molecules of gases on right side. So, the number of gaseous molecules is increasing and hence the entropy is also increasing.

So, the correct choice is (A), entropy is increasing.(Positive sign)

(25) The given equation is...

Cgraphite(s) at 0oC --> Cgraphite(s) at 25oC

here, no phase is changing but since entropy is temperature dependent. It incraeses as the temperature is increased. Here, temperature is increasing from 0 degree C to 25 degree C, hence, there would be an increase in entropy.

The correct choice is (A), entropy is increasing. (Positive sign)

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