This shows how to calculate pOH when given the hydroxide ion concentration and how to calculate hydroxide ion concentration when given the pOH. A few examples of each process are presented
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0:00do dislike pH is shorthand method expressing
0:07grozny 9 concentration P oooh
0:10is a shorthand method expressing hydroxide ion concentration
0:14in a solution first will go over how to find P oooh
0:18if forgiven oooh minus concentration
0:21P oooh is defined as the negative log that the hydroxide ion concentration
0:28P oooh uses the same rules for significant figures
0:32as pH
0:33only digits to the right the decimal point in it P oooh
0:37are counted as significant figures for example
0:40let's say the P 00 H have a solution is 10.15 three
0:45the one and 20 in the gray color tan
0:48are both on the left side the decimal place so they are not significant
0:53figures
0:54but the green colored one along with the 5&3
0:58are all on the right side s my place
1:01so they are significant figures
1:04so Ipoh a 10-point 153
1:08has three significant figures
1:10here are three examples for you to try pause the video at this point to try to
1:15fill in the rest to the table for these
1:17make sure you express your PO wage to the correct number
1:20up significant figures
1:22then you can reason the video to check your answers and make any necessary
1:26corrections
1:28will start but 2.25 Mothercare wage
1:32heal each is a strong base which completely dissociate into 1k plus
1:36and 108 minus sign
1:39the concentration Okoh is always point to five mauler
1:42the mole ratio ball weight minus ticking away just 121
1:47so the concentration a boy minus is also be able to point to thrive mauler
1:52so the PO age will be negative log at the hydroxide and concentration
1:56or the negative log a point to decide
2:00which comes out 2.60 this expressed
2:03two significant figures the same as the number in a given concentration pointy
2:08side
2:08smaller
2:09now look at the NaOH solution Neoh is a strong base which dissociates completely
2:15into one an a plus I and and 108 minus sign
2:20the concentration of NaOH as a whole is 1.35 times tend to the -3 molar
2:27and the mole ratio oooh -2 Neoh
2:30is just 121
2:31so the concentration of hydroxide is 1.35 times tend to the -3 molar
2:37and appeal wages the negative log a 1.3 by
2:41and stand in the negative three
2:43which comes out the two-point 870
2:46this is expressed his three significant figures like to get in concentration
2:50value
2:52lastly will look at the SR oooh to solution
2:56strontium hydroxide is a soluble strong base
2:59which completely dissociate into one SRT plus I and 2008 minus signs
3:04the concentration at best rooh to you as a whole
3:07his point 082 molar
3:10because patients and their dissociation equation housed at the mall ratio
3:14hydroxide SR oooh to student one
3:17so the concentration by drug side is two times 1082
3:21which is point 164 molar
3:24this is one more significant figure in the point 082
3:27but will use this value and see the ramming into last step
3:31EP 08 is the negative log the point 164
3:35which one rounded to two significant figures comes out 2.79
3:40the rounded ST two significant figures because the point 082 molar
3:44at two significant figures
3:46now what we're over how to find the hydroxide and concentration of a
3:49solution
3:50ever given the PO age
3:53to do this we used a formula concentration hydroxide easy credit and
3:57the negative here wage
3:59tended to negative poha is called the anti dog up the negative PO age
4:05when you doing this calculation make sure you use the negative
4:08PO age value Medina PO age value itself
4:12here's an example question were given it to peel away to a solution a penny a
4:16wage
4:17his point 815
4:19and rest to find the concentration of NaOH as a whole
4:23pause the video and tried this on your own first then reason the video
4:27to check your answer
4:29a good plan for this problem would be to start with the PO age
4:33then converted to hydroxide ion concentration
4:36and from that find the concentration of NaOH
4:39as a whole
4:41we start by finding the hydroxide ion concentration
4:44we use the form with a concentration of hydroxide is tended the negative booh
4:49as substitute pointing 15 and drippy oh wait
4:53so the cross streets HH minus is equal to 10 to the power of negative point 81
4:58by
4:59which equals .1 53 mauler this says three significant figures
5:03like to give in P O eight we need one by
