Question

Need help with algebra 2 question! See attachment.

Answer 1

Please look at the given formula. Copy it down.

Note that [H+] is given and is 4.3*10^(-14).

Answer 2

Just substitute this VALUE for [H+] into the formula, calculate the log, and then put a negative sign in front of it.

Answer 3

so pH = -log4.3*10^(-14)

Answer 4

then pH=-log4.3-log10^(-14) ?

Answer 5

Enclose the argument (4.3 ....) in parentheses. Otherwise you're doing fine.
You'll need to evaluate that log.
Then, you'll need to negate the value of the log (put a - sign in front of it).

Answer 6

I'm stuck on evaluating the log -log4.3

Answer 7

I know -log10^(-14) is just (-14)

Answer 8

You have too many - signs in your expression. Only one of them belongs there. CAn you fix this?

As before, evaluate log (..... ) before writing the neg. sign in front of it.

Answer 9

(-14)?

Answer 10

[H+] is given and is 4.3*10^(-14). 4.3 * 10^(-14) is a product. What is the product rule for logs?

True, log 10^(-14) is -14.

Answer 11

logbAC = logbA + logbC

Answer 12

Yes, that's correct. So, whats the log of the product 4.3 * 10^(-14) ?

Answer 13

ehh, i'm stumped

Answer 14

What's the log of 4.3?

What's the log of 10^(-14)?

Whats the log of the product of those two quantities?

Answer 15

oh wait is it -0.63347?

Answer 16

for -log4.3

Answer 17

I was hoping you'd evaluate the 2 logs and then add the results together before brining in that negative sign.

You have already told me, correctly, that log 10^(-14) is -14.
What is the log of 4.3?

Answer 18

the log of 4.3 is 0.63347 right?

Answer 19

Yes, that looks good.
Now, add to gether that 0.63347 and that -14. Can you explain why this is necessary?

Answer 20

Note that one is positive and the other negative.

Answer 21

would you solve it like log0.63347 * -14

Answer 22

No, you no longer need that "log" operator, because you've already found the logs of 4.3 and 10^(-14).

Answer 23

ohh okay so it's just 0.63347 * -10?

Answer 24

This isn't multiplication, so throw out that *.
Combine (do not multiply) 0.63347 and -14.

Answer 25

* means multiplication
+ denotes addition

Answer 26

I got -9.366..

Answer 27

oh wait careless mistake, now my answer is -13.366..

Answer 28

much better.
Now negate that result (multiply it by -1).
\

Answer 29

it is it's reciprocal, 13.3?

Answer 30

No. You have -13.366, which is a negative number, and need only multiply that negative number by -1. what is the result of that?

It's true that an EXPONENT of -1 indicates reciprocal in some cases, but not in this one.

Answer 31

the result of -13.366 * -1 is 13.366?

Answer 32

right, and that's to 3 decimal places. How many decimal places were called for?

Answer 33

it rounds to 13.4 right?

Answer 34

Right. That's rounded off to the nearest 10th.

Your answer? "The approximate pH is ... ?"

Answer 35

The appoximate pH is 13.4

Answer 36

Right. Very good. Any questins about this procedure?

Answer 37

Not anymore, thank you so much for your help!

Answer 38

You're welcome. Best of luck to you, and M. C. Bye!