14.5 part d

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Emily Glaser 1F
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Joined: Thu Jul 27, 2017 3:01 am

14.5 part d

Postby Emily Glaser 1F » Mon Feb 19, 2018 5:00 pm

For the reduction reaction of P4 --> 4PH3

Why do I not add an H2O on right side (the side that is reduced state) just like it did in all the previous problems

Isaiah Little 1A 14B
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Re: 14.5 part d

Postby Isaiah Little 1A 14B » Mon Feb 19, 2018 6:11 pm

You would only add H2O to balance out the number of oxygen atoms in a reaction. Otherwise, to balance the number of hydrogen atoms in a redox reaction, you would add H+ ions to whichever side as needed. Then to balance the charges, you would add electrons as necessary. In this case, the reaction would be 4 P4 + 12 H+ + 12 e- ===> 4 PH3

Kathleen Vidanes 1E
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Re: 14.5 part d

Postby Kathleen Vidanes 1E » Tue Feb 20, 2018 10:06 pm

I was confused about this, too. Wouldn't adding H+ ions indicate that the reaction is taking place in an acidic solution rather than a basic solution, though?

lauren chung 2f
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Joined: Fri Sep 29, 2017 7:03 am

Re: 14.5 part d

Postby lauren chung 2f » Wed Feb 21, 2018 9:12 am

You wouldn't add H+ since it is in basic solution. You would have to balance with OH- and H20.

McKenna disc 1C
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Re: 14.5 part d

Postby McKenna disc 1C » Wed Feb 21, 2018 4:40 pm

Emily Glaser 1F wrote:For the reduction reaction of P4 --> 4PH3

Why do I not add an H2O on right side (the side that is reduced state) just like it did in all the previous problems


You don't need any more H's on that side in order to balance that equation! That's why you wouldn't need an H2O. :)
I was super confused about when to add OH- and H2O and H+ when I was balancing, but what I found helpful was the toolbox and the examples at the beginning of the chapter. The toolbox outlines the procedures for both acidic and basic solutions and there's an example for both a basic and acidic solution.

Grace Han 2K
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Re: 14.5 part d

Postby Grace Han 2K » Thu Feb 22, 2018 10:14 am

H2O is added to balance the rxn if you have to balance Oxygen, however there are no oxygen present, so you could skip that step and add H+.

Ethan-Van To Dis2L
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Joined: Fri Sep 29, 2017 7:05 am

Re: 14.5 part d

Postby Ethan-Van To Dis2L » Fri Feb 23, 2018 1:36 am

In this case you would H+ ions, and then later on the OH- ions would combine with the H+ ions to make water.

lindsay lathrop 2C
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Joined: Sat Jul 22, 2017 3:00 am

Re: 14.5 part d

Postby lindsay lathrop 2C » Sat Feb 24, 2018 2:46 pm

Kathleen Vidanes 1E wrote:I was confused about this, too. Wouldn't adding H+ ions indicate that the reaction is taking place in an acidic solution rather than a basic solution, though?

Yeah I was confused about this process too but all you need to do is balance with the H+ and then to make it so it takes place in a Basic solution you just add one OH- to both sides for every H+. Then you combine the OH- and H+ to form water and cancel out any extra H2Os.


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