Please explain to me how to calculate pH of solution given a [H3O+] ion concentration

I'm really confused. Something about pH = -log [H3O+] when the base to the log is -10. How am I supposed to plug all this into the calculator?

For #1, I have 0.1 mol L-1 [H3O+] concentration.

Thank you in advance! :-)

Please explain to me how to calculate pH of solution given a [H3O+] ion concentration?
I'm really confused. Something about pH = -log [H3O+] when the base to the log is -10. How am I supposed to plug all this into the calculator?


For #1, I have 0.1 mol L-1 [H3O+] concentration.

Type LOG, the screen shows log(
Type LOG 0.1) Enter, the screen shows log (0.1)
Answer = -1

The log of 0.1 = -1
pH = -log means multiply the answer by -1
-1 * -1 = +1
pH = +1

Base 10 means the 10 is raised to a specific power.

0.1 = 10^-1
the log is the exponent. log 10^-1 = -1
the –log 10^-1 = +1
pH = 1

Examples
[H3O+] ion = 0.01 = 10^-2
log (10^-2) = -2
-log (10^-2) = 2
pH = 2

[H3O+] ion = 1 * 10^-4
log (10^-4) = -4
-log (10^-4) = 4
pH = 4

[H3O+] ion = 5 * 10^-4
log(5 * 10^-4) ENTER
Answer = -3.301
pH = +3.301

In the calculator, the EE button is used for scientific notation!
5 EE-4 = 5 * 10^-4

I hope this helps!!