How to find pH and H+:
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The pOH scale is the opposite of the pH scale.
A pOH of 1 is a string base and a pOH of 14 is a strong acid.
A pOH of 1 is a string base and a pOH of 14 is a strong acid.
Let's try some examples!
If there are 0.1 H+ ions in a substance what is the pH?
If there are 0.1 H+ ions in a substance what is the pH?
- Type -log(0.1) in your calculator. (If you are having trouble pressing the button use the negative sign on your keyboard)
- The answer should be 1.
- The pH of this substance is one.
More Questions!
If a substance has a pOH of 3, how many OH- ions are there?
Let's try something harder this time!
You are given 11 for the pOH. Find the OH- ions, pH, H+ ions?
First let's find the pH because the equation is pOH + pH = 1
We can switch the equation to pH= 14 - pOH. Since when know the pOH let's plug the number in! pH= 14-11= 3 pH=3
Now, let's find the number of OH- ions.
Equation: OH- = 2nd log [-pOH]
Plug: 2nd log (-11) into your calculator. The answer should be 0.00000000001.
Time to find the number of H+ ions.
Equation: H+ = 2nd log [-pH]
Plug: 2nd log (-3) into your calculator. The answer should be 0.001.
Answers for this question: pOH= 11, OH- = 0.00000000001, pH= 3, H+ = 0.001
Now, try this question on your own:
If you are given a pH of 4, how many OH- ions are there?
If a substance has a pOH of 3, how many OH- ions are there?
- Type 2nd log (-3) into your calculator. (On the calculator provided not his website click "10^x")
- Don't forget you use -pOH when finding the number of OH- ions.
- Your answer should be 0.001.
Let's try something harder this time!
You are given 11 for the pOH. Find the OH- ions, pH, H+ ions?
First let's find the pH because the equation is pOH + pH = 1
We can switch the equation to pH= 14 - pOH. Since when know the pOH let's plug the number in! pH= 14-11= 3 pH=3
Now, let's find the number of OH- ions.
Equation: OH- = 2nd log [-pOH]
Plug: 2nd log (-11) into your calculator. The answer should be 0.00000000001.
Time to find the number of H+ ions.
Equation: H+ = 2nd log [-pH]
Plug: 2nd log (-3) into your calculator. The answer should be 0.001.
Answers for this question: pOH= 11, OH- = 0.00000000001, pH= 3, H+ = 0.001
Now, try this question on your own:
If you are given a pH of 4, how many OH- ions are there?