finding molarity

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Kaylee Clarke 1G
Posts: 103
Joined: Fri Aug 30, 2019 12:15 am

finding molarity

Postby Kaylee Clarke 1G » Thu Dec 05, 2019 4:46 pm

how do you find the molarity of an acid or base? is molarity what is used to find the pH, and resulting pOH?

Caitlyn Tran 2E
Posts: 100
Joined: Fri Aug 09, 2019 12:15 am

Re: finding molarity

Postby Caitlyn Tran 2E » Thu Dec 05, 2019 5:27 pm

Molarity of an acid and base is the same as molarity of any solution, which we learned about in the beginning of the quarter. It is simply the number of moles of solute divided by the total volume of the solution. However, for acids and bases specifically, we need to know how normal molarity relates to the molarity of hydronium and hydroxide ions. Strong acids and bases completely dissociate in solution, so their concentration is equal to the concentration of hydronium ions (for acids) or hydroxide ions (for bases) assuming that there is one mole of hydronium/hydroxide ions per mole of solute. The concentration of hydronium ions is used to calculate pH while the hydroxide ion concentration is used to calculate pOH. If you know one, you can always calculate the other by subtracting the value you have from 14. Hope this helps!

Audrie Chan-3B
Posts: 50
Joined: Thu Jul 25, 2019 12:17 am

Re: finding molarity

Postby Audrie Chan-3B » Thu Dec 05, 2019 6:30 pm

Finding molarity for an acid or base is the same way as finding the molarity in the fundamentals chapter (Molarity = moles/ volume (L)). You can also find molarity through pH. By taking the inverse log when the pH or pOH is known, you can find the respective acid or base molarity.

Kaylee Clarke 1G
Posts: 103
Joined: Fri Aug 30, 2019 12:15 am

Re: finding molarity

Postby Kaylee Clarke 1G » Fri Dec 06, 2019 12:29 am

Caitlyn Tran 1G wrote:Molarity of an acid and base is the same as molarity of any solution, which we learned about in the beginning of the quarter. It is simply the number of moles of solute divided by the total volume of the solution. However, for acids and bases specifically, we need to know how normal molarity relates to the molarity of hydronium and hydroxide ions. Strong acids and bases completely dissociate in solution, so their concentration is equal to the concentration of hydronium ions (for acids) or hydroxide ions (for bases) assuming that there is one mole of hydronium/hydroxide ions per mole of solute. The concentration of hydronium ions is used to calculate pH while the hydroxide ion concentration is used to calculate pOH. If you know one, you can always calculate the other by subtracting the value you have from 14. Hope this helps!

thank you so much!!!

Bradley Whitworth 4B
Posts: 54
Joined: Sat Jul 20, 2019 12:17 am

Re: finding molarity

Postby Bradley Whitworth 4B » Fri Dec 06, 2019 9:14 pm

Molarity is no different for acids/bases than any other solution. It is important to understand what pH and pOH are though which is the -log base 10 of either H ion concentrations or OH ion concentrations so by raising the -pH or -pOH as a power of 10 then you can find the molarity of ions in that solution.


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