Question

NEED HELP, TAKING A FINAL EXAM!!
If the quantity of H3O+ ions in a solution is equal to the quantity of OH- ions, what would be the pH value?
Answer

1

4

7

11

Answer 1

7

Answer 2

A solution has a [OH-] of 1 × 10-12. What is the pOH of this solution?
Answer

2

7

10

12

Answer 3

We know the formula for pOH to be
\[pOH = -\log[OH^-]\]
So if you take the negative log of 1E-12, you'll get the pOH.

Answer 4

can you show the steps?

Answer 5

Really you can just use a calculator lol

Answer 6

all i have is the plain pelletty one on the computer lol

Answer 7

excuse my language.

Answer 8

nvm...

Answer 9

Alright, I'll skip explaining how to manually calculate logs lol

It's 12. In 99.9% of circumstances when doing chemistry you'll have a calculator and you can just type -log(1x10^-12)

Answer 10

yeah i have just misplaced my calculator and dont have the log sin or tan buttons. verysimple one tonight my friend.

Answer 11

In compounds, what is the oxidation number of group VIIA compounds?
Answer

1-

3 +

5 +

7 +

Answer 12

Group VIIA being halogens, correct?

Answer 13

i only have a few more questions, will you help me finish so i can pass and you can get on your way lol

Answer 14

yes

Answer 15

I don't mind helping. I like chemistry. Halogens are really close to an octet, and want one electron really bad. They're all -1 normally.

Answer 16

alright next one lol
What is the oxidation number of O in H2O2?
Answer

-2

-1

+1

0

Answer 17

Oxygen is normally -2, but H2O2 is the exception. It's -1.

Answer 18

is it 1?

Answer 19

oh nvm haha

Answer 20

getting a little tougher now
What is the oxidizing agent in the following equation?

Al (s) + 3 Ag+ (aq) → Al+3 (aq) + 3 Ag (s)
Answer

Al (s)

Ag+ (aq)

Al+3 (aq)

Ag (s)

Answer 21

The oxidizing agent is the thing that accepts the electron. We see that Al goes from 0 to +3, meaning it lost 3 electrons. By deduction we then know that Ag was reduced and is the oxidizing agent.

Answer 22

It's Ag+ as it was reduced to Ag

Answer 23

As aq or Ag s?

Answer 24

Aqueous

Answer 25

2 more
To balance the following half-reaction, Cr3+ → CrO4-, how many waters need to be added?
Answer

4 waters to the product side

2 waters to the product side

4 waters to the reactant side

2 waters to the reactant side

Answer 26

How are voltaic cells and electrolytic cells similar?
Answer

Both occur due to spontaneous reactions.

Both require the input of energy.

Both have a negative charge on the anode.

Both cells use oxidation-reduction reactions.

Answer 27

Alright, I'll answer one at atime

Answer 28

alright..

Answer 29

For the first one, you'd need 4 H2O to the reactants side.

Answer 30

thats what i thought but i would rather be safe than sorry, alright the last one now

Answer 31

And both types of cells do redox reactions.

Answer 32

oxidation reduction?

Answer 33

yes