Calculate pOH

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sarahtang4B
Posts: 132
Joined: Fri Sep 28, 2018 12:27 am

Calculate pOH

Postby sarahtang4B » Tue Jan 15, 2019 1:14 pm

When we calculate pOH for Ba(OH)2, why do we multiply the concentration by two?

Is it because there's two OH?

Rimsha Hussaini 1A
Posts: 31
Joined: Fri Sep 28, 2018 12:20 am

Re: Calculate pOH

Postby Rimsha Hussaini 1A » Tue Jan 15, 2019 1:22 pm

To put it simply, yes.

The chemical equation of the dissociation of Ba(OH)2 is Ba(OH)2 -> 2OH- + Ba2+
This indicates that in the dissociation of Ba(OH)2, 2 hydroxide ions form.

Katie Sy 1L
Posts: 57
Joined: Fri Sep 28, 2018 12:18 am

Re: Calculate pOH

Postby Katie Sy 1L » Tue Jan 15, 2019 1:23 pm

yes because of the 2 hydroxide ions

EllerySchlingmann1E
Posts: 76
Joined: Fri Sep 28, 2018 12:24 am

Re: Calculate pOH

Postby EllerySchlingmann1E » Tue Jan 15, 2019 3:57 pm

You have to multiply the concentration by two because of the molar ratio between Ba(OH)2 and hydroxide ions. If you don't recognize the difference in moles, your calculation and pH will be way off. Another reason why it's so important to have a balanced reaction before your start making any assumptions or calculations.


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