Question

Which of the following processes has an increase in entropy?

Answer 1

A) Boiling a pot of water
B) Freezing a sample of water
C) Filtering sand out of a sample of water
D) Synthesizing water from hydrogen and oxygen

Answer 2

I think it is B

Answer 3

not quite, think about what entropy is normally defined as "randomness".

Freezing water fixes the location of atoms/molecules, so you're actually decreasing the "randomness" of the system.

Answer 4

So will it be D?

Answer 5

hm no. by taking 2 molecules (\(O_2\) and \(H_2\)) and making them one (water), you're actually decreasing the entropy of the system.

You want a scenario where the spacing between molecules (and their ability to move) is greater than what you started with. Or making 2 (or more) things out of 1, e.g. decomposition reactions.

Answer 6

So it will be a because when you boil water the molecules space out and become gas

Answer 7

@aaronq Am i correct? I'm not 100% sure

Answer 8

yep! thats exactly it

Answer 9

Can you help me with another question?

Answer 10

shoot

Answer 11

Which of the following changes has a decrease in entropy?
A) N2O4 ---> 2NO2
B) C6G6----> C6H6
C) 2LiCIO3 ---> 3O2+2LiCl
D)3Fe=2O2---> fe3O4
Would it be c because they are two elements coming out of it?

Answer 12

it's not C. Recall that making more particles (from those that you started with) is an \(\sf increase\) in randomness.

Answer 13

So its D?

Answer 14

\(\Large \checkmark\)

Answer 15

I have two more that i need help on. one i don't even know what to put

Answer 16

post them?

Answer 17

Which of the following changes will always be true for a system with increasing entropy?
A) - (triangle) G
B) +(triangle)T
C) +(triangle)S
D) -(triangle)H

Answer 18

S means entropy

Answer 19

\(\Delta \) means change

Answer 20

so its c

Answer 21

yep

Answer 22

Which of the following combinations will result in a reaction that is never spontaneous?
A) Positive enthalpy change and positive entropy change
B) Positive enthalpy change and negative entropy change
C) Negative enthalpy change and positive entropy change
D)Negative enthalpy change and Negative entropy change

Answer 23

I think its C

Answer 24

That would actually be always spontaneous. This formula is the guideline for spontaneity of chemical reactions:

\(\Delta G=\Delta H-T\Delta S\)

\(\Delta G<0\) spontaneous
\(\Delta G>0\) non-spontaneous

Answer 25

so it will be b

Answer 26

yes!

Answer 27

Thanks for the help!

Answer 28

no problem!