[flagpolesitta43]

I have my final tomorrow and I was hoping you guys could help me with some true or false questions, since I always lose points on these questions. I've answered most of them so if you can just let me know which ones I answered correctly that would really help me out. Thanks!

1. A catalyst changes the equilibrium constant for a reaction. (false)
2. A catalyst changes the rate constant for a reaction. (false)
3. Water acts as a Lewis acid when it forms a complex ion with transition metals. (true)
4. The rate-determining step is the slowest step in a reaction mechanism. (true)
5. If a process is reversible, there is no change in the entropy of the universe. (true)
6. Samples of the same polymer may have different average molecular weights. (?)
7. Polymers formed from two different types of monomers are called copolymers. (true)
8. Nuclear fission occurs when an atomic nucleus splits into two lighter nuclei. (true)
9. The hal-life of a reagent is the amount of time required for the concentration of that reagent to drop to 1/2 of it's original value. (true)
10. For a system at equilibrium, the reaction quotient equals the equilibrium constant. (true)
11. A system is at equilibrium when the rate of the forward reaction and the rate of the reverse reaction are equal. (true)
12. A Lewis acid acts as an electron pair donor. (False)
13. An Arrhenius base generates an excess of OH- ions in solution.
14. All carboxylic acids are weak acids. (?)
15. A buffer solution is formed by adding a large excess of acid to a solution containing its conjugate base. (true)
16. When a weak acid is titrated against a strong base, the equivalence point occurs at a pH greater than 7. (false)

Thanks again.

[rctrackstar2007]

I have my final tomorrow and I was hoping you guys could help me with some true or false questions, since I always lose points on these questions. I've answered most of them so if you can just let me know which ones I answered correctly that would really help me out. Thanks!

1. A catalyst changes the equilibrium constant for a reaction. (false)
2. A catalyst changes the rate constant for a reaction. (false)
3. Water acts as a Lewis acid when it forms a complex ion with transition metals. (true)
4. The rate-determining step is the slowest step in a reaction mechanism. (true)
5. If a process is reversible, there is no change in the entropy of the universe. (true)
6. Samples of the same polymer may have different average molecular weights. (?)
7. Polymers formed from two different types of monomers are called copolymers. (true)
8. Nuclear fission occurs when an atomic nucleus splits into two lighter nuclei. (true)
9. The hal-life of a reagent is the amount of time required for the concentration of that reagent to drop to 1/2 of it's original value. (true)
10. For a system at equilibrium, the reaction quotient equals the equilibrium constant. (true)
11. A system is at equilibrium when the rate of the forward reaction and the rate of the reverse reaction are equal. (true)
12. A Lewis acid acts as an electron pair donor. (False)
13. An Arrhenius base generates an excess of OH- ions in solution.
14. All carboxylic acids are weak acids. (?)
15. A buffer solution is formed by adding a large excess of acid to a solution containing its conjugate base. (true)
16. When a weak acid is titrated against a strong base, the equivalence point occurs at a pH greater than 7. (false)

Thanks again.

looks alright to me, i don't know about 5,6  . 13 is true and so is 14 .

someone check those two please

[Borek]

2. A catalyst changes the rate constant for a reaction. (false)
16. When a weak acid is titrated against a strong base, the equivalence point occurs at a pH greater than 7. (false)

Think these two over.

13. An Arrhenius base generates an excess of OH- ions in solution.

What every base does to the solution?

14. All carboxylic acids are weak acids. (?)

Mostly true.

15. A buffer solution is formed by adding a large excess of acid to a solution containing its conjugate base. (true)

As for me normal excess will be enough, no need for large

Disclaimer: just because I have not listed an answer doesn't meant it is OK.

[tennis freak]

I have my final tomorrow and I was hoping you guys could help me with some true or false questions, since I always lose points on these questions. I've answered most of them so if you can just let me know which ones I answered correctly that would really help me out. Thanks!

1. A catalyst changes the equilibrium constant for a reaction. (false)
2. A catalyst changes the rate constant for a reaction. (false)
3. Water acts as a Lewis acid when it forms a complex ion with transition metals. (true)
4. The rate-determining step is the slowest step in a reaction mechanism. (true)
5. If a process is reversible, there is no change in the entropy of the universe. (true)
6. Samples of the same polymer may have different average molecular weights. (?)
7. Polymers formed from two different types of monomers are called copolymers. (true)
8. Nuclear fission occurs when an atomic nucleus splits into two lighter nuclei. (true)
9. The hal-life of a reagent is the amount of time required for the concentration of that reagent to drop to 1/2 of it's original value. (true)
10. For a system at equilibrium, the reaction quotient equals the equilibrium constant. (true)
11. A system is at equilibrium when the rate of the forward reaction and the rate of the reverse reaction are equal. (true)
12. A Lewis acid acts as an electron pair donor. (False)
13. An Arrhenius base generates an excess of OH- ions in solution.
14. All carboxylic acids are weak acids. (?)
15. A buffer solution is formed by adding a large excess of acid to a solution containing its conjugate base. (true)
16. When a weak acid is titrated against a strong base, the equivalence point occurs at a pH greater than 7. (false)

Thanks again.

i think that 5 is true but 6 i have no idea on

[Borek]

6 is probably true.

[Organishe]

You'll want to rethink 3. For water to form a complex ion with a transition metal, it would have to donate electrons to the metal atom, and things that are electron pair donors are _____ _____. (hint: your answer to # 12 is correct)

for 5 I would say false (I'm not positive on this). For example, think of the melting of ice into water.

H₂O_(s) + energy <--->   H₂O_(l)

Certainly this is a reversable process, but moving to the right gives an increase in the entropy of the universe, right?

As for 6, I agree with Borek, certainly the same polymer can have different molecular weights.

[tennis freak]

oh yeah thanks for the better explanation of number 5 that makes sense

[Yggdrasil]

for 5 I would say false (I'm not positive on this). For example, think of the melting of ice into water.

H₂O_(s) + energy <--->   H₂O_(l)

Certainly this is a reversable process, but moving to the right gives an increase in the entropy of the universe, right?

5 is true by the definition of a reversible process. Organishe is just looking at what happens to the system.  When ice melts, the system increases in entropy.  But, to answer this question you have to also consider what happens to the surroundings.  When ice melts, heat is removed from surroundings, which decreases the entropy of the surroundings.  So, when you consider the total change in entropy (the change in the entropy of the universe) the change is not necessarily positive.  For a reversible process, the change in entropy of the system is equal to the (negative) change in entropy of the surroundings.  For example, the irreverible melting of water at temperatures of above 0 C removes less entropy from the surroundings than is gained by the water.  However, at 0 C, the entropy which is gained by water melting reversibly equals the entropy lost by the surroundings.

[tennis freak]

ok apparently i was right but had no idea why, but thank you for explaining each side so now i can get in an argument with people.

[Organishe]

oh curses knew I missed something.     okay ignore what I said about the entropy thing then.