- Joined
- May 22, 2017

- Messages
- 80

- Reaction score
- 48

**#1. If [H+] = 6.4x10-8M, what is the pH of the solution?**

- 6.8

- 8.3

**7.2**

- 7.8

Method:

- Take the power and subtract 1 (8-1) =**7.**__

- Take the front number and subtract 10. 10-6.4=**3.6**

- pH**~**7.36

- closest answer is 7.2 and thats the winner.

**#2: If [OH-] = 6.0 x 10-10M, what is the pH of the solution?**- 4.1

**4.8**

- 5.2

- 8.8

Method:

- Take the power and subtract 1 (10-11) = 9**.**__

- Take the front number and subtract 10. 10-6=**4**

- pOH**~**9.4

- pH+pOH=14 --> pH= 4.6; Closest answer is 4.8 and thats the winner

**#3. Reverse style problem: If the pH is 3.2, what is the [H+] of the solution?**

- 2.1x10-3M

- 8.9x10-3M

- 6.3x10-4M

**8.9x10-5M**

Method:

- Take 3 and +1 (instead of subtracting 1 like before) = a power of**4**

- In this case only one power of 4 answer. thats the winner.

**#4. If the pOH is 9.1, what is the [OH-] of the solution?**

- 6.9x10-9M

- 8.6x10-8M

- 1.6x10-10M

**7.9x10-10M**

Method:

- 9+1 = 10. 10 is the power

- 10- second decimal place= 9 l closest one is 7.9

This is really a sloppy method but it works for me and i got all answers right. if its too risky, or if its not accurate enough someone let me know.

- 2.1x10-3M

- 4.1