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14.5 part d

Posted: Mon Feb 19, 2018 5:00 pm
by Emily Glaser 1F
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

Re: 14.5 part d

Posted: Mon Feb 19, 2018 6:11 pm
by Isaiah Little 1A 14B
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

Re: 14.5 part d

Posted: Tue Feb 20, 2018 10:06 pm
by Kathleen Vidanes 1E
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?

Re: 14.5 part d

Posted: Wed Feb 21, 2018 9:12 am
by lauren chung 2f
You wouldn't add H+ since it is in basic solution. You would have to balance with OH- and H20.

Re: 14.5 part d

Posted: Wed Feb 21, 2018 4:40 pm
by McKenna disc 1C
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.

Re: 14.5 part d

Posted: Thu Feb 22, 2018 10:14 am
by Grace Han 2K
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+.

Re: 14.5 part d

Posted: Fri Feb 23, 2018 1:36 am
by Ethan-Van To Dis2L
In this case you would H+ ions, and then later on the OH- ions would combine with the H+ ions to make water.

Re: 14.5 part d

Posted: Sat Feb 24, 2018 2:46 pm
by lindsay lathrop 2C
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.