what is the ph of a solution with [oh-] = 1 × 10-4 m? This is a topic that many people are looking for. bluevelvetrestaurant.com is a channel providing useful information about learning, life, digital marketing and online courses …. it will help you have an overview and solid multi-faceted knowledge . Today, bluevelvetrestaurant.com would like to introduce to you Calculating pH from [OH-] hydroxide Concentration – CLEAR & SIMPLE. Following along are instructions in the video below:
Dudes misterpost and non tonights video. The goal is for you to be able able to calculate the ph of a solution from the oah concentration. This is the ion concentration express the molarity and from that tonight.
You need to say what the ph is so the goal is for you to calculate the ph given the base concentration. Were going to do a few examples tonight guys so lets jump into it little background information. When im expressing something in these brackets here.
I am expressing the concentration of that specific thing. And its going to be expressed in molarity and thats going to be moles per liter. So this is going to be my base concentration.
My hydroxide ion concentration. But something new is this tonight. Okay when i multiply my hydronium or h.
Ion concentration by the hydroxide ion concentration. I will always end up with this number 1 times 10 to the negative 14. And thats huge when we using that a lot tonight and so just get ready to use it dudes the steps necessary are to so in order to calculate the ph given my hydroxide or base concentration.
I need two steps the first is going to involve solving for the h. Ion concentration. Now im going to use this right here guys.
The brand new formula that i showed you so if i give you this if i give you that.
And you also are given this were going to use a little bit of algebra to rearrange the equation to say the h. Ion concentration is going to be equal to 1 times 10 to the negative 14 divided by the hydroxide concentration and thats going to be expressed in the problem. Youll have that number step two is going to now plug this value into my ph formula.
Remember the ph was the negative log of the h ion concentration once you have that number you plug it in down here. And youre going to find yourself the ph also viewers check this out when i mentioned h. I could also interchangeably be expressing the h3o.
Plus ion concentration. Theyre often used in the same exact light in our first example tonight we see we are asked to calculate the ph of a solution and the solution is a base. I have a hydroxide ending the o h.
Ending and the hydroxide has a concentration of 3 times. 10 to the second molar negative second molar step one were going to use the same as before is going to be to use my formula. The h.
Concentration. Plus. My oh h.
Hydroxide ion concentration equals 1. Times 10 to the negative. 14.
Thats always going to be you know part of my first step is going to be you use that equation to solve for my h ion concentration.
When we rearrange this as we saw before the h. Ion concentration is going to be equal to 1 times 10 to the negative. 14.
Divided by my hydroxide ion concentration. Which the problem tells us is 10 3 times. 10.
To the negative second. Once i crunch. Those numbers of 1 times.
10 to negative 14 3. Times. 10.
To the negative second. I find out that the hydrogen ion concentration is going to be equal to three point three three times 10. The negative.
13. So that is part one i kind of have my hydrogen ion concentration right now right there. And that is really cool awesome part.
I see that my exponent value is around 13.
That means my ph just a. Little. You know heads up your ph.
Should be around. There. My ph is going to be between 12 and 13.
Most likely thats what the exponent is going to give me a little heads up for step two were going to use that ion concentration in my ph formula because the ph of a solution is equal to the negative log of the hydrogen ion concentration and when i substitute that previous value into this formula and then take the negative log of that we find out that the ph is going to be equal to 125. Excellent. Do it so once again.
Two steps are needed to solve this problem try the next problem on your own see how you do in this example were asked to calculate ph of a solution of naoh with a concentration of 35 times 10 to the negative 5th molar. So were going to go our two steps again step one lets use. The formula of the hydrogen ion concentration multiplied by the hydroxide ion concentration equals one times 10 to the negative.
14 step two a little rearrangement as we always do the h is going to be equal to one times 10 to the negative 14. Divided by my hydroxide concentration of three point five times 10 to the negative fifth and we solve the numbers and end up finding out the hydrogen ion concentration is two point eight six times ten to the negative tenth awesome dudes thats part one here thats my first part of this one step number two is going to be to use the concentration in my ph form of the ph is the negative log of the h ion so we plug the number in the ph is going to be equal to negative log of two point eight six times 10 to the negative 10 and our ph is going to have a value of nine point five. Once again does that sound right.
Yeah it is in the ballpark of that. Exponent so ph is. 95.
This is a basic solution alright basic solution now anything over a ph of seven would be considered a basic solution alright dudes.
Lets try the next problem in this problem im throwing your curve ball. I want you to calculate the ph of a solution once again im giving you the concentration of the base. But this time.
The base has two hydroxide ions that are going to dissociate when it hits the water so even though i give you the concentration of the base youre going to need to double that to account for the doubling of the ions of hydroxide that will go into solution all right dudes same way as we always do lets use the concentration formula again lets plug in our values h. Is going to be equal to 1 times 10 to the negative 14. Divided by in this case check this out dude.
You gotta be really careful. Here were going to divide this by 2 times 45. Times.
10 to the negative ninth and i did that because there were two hydroxide ions. When we use their value. The hydrogen ion concentration in solution is one point 1 1.
Times. 10 to the negative sixth. Awesome.
Thats part one weve gotten the concentration thats essential for step two in step two were using the ph formula the ph equals. The negative log of the h ion lets plug our values in guys. And solve for the ph.
And we end up finding the ph is going to be equal to five point nine five you know once again thats in the ballpark of my exponent right there all right dudes thats all the examples for tonight. I hope it was helpful i hope it brought some clarity to this topic for you right man. Thanks.
A lot guys for tuning again have a good night peace .
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