AP CHEM +k

[EVAN.F]

help would be much appreciated. +k

Calculate the OH- ion concentration and pH of the following solution: .080M Na2CO3

 

[dwhite]

i too am having trouble on like the same thing....i dont really know whats going on

 

[robtheslobonacob]

is that the whole question or is there some more info about volume and whatnot?

 

[Slinger1x1]

im in normal chem, but im going into AP next year

i feel like your leaving something out

 

[EVAN.F]

oh right, Ka value for H2CO3 is 4.3 x 10^-7, Ka2 is 5.6 x 10-11 (except im not sure you need this)

I'm not sure if the balanced equation is

(CO3)2- + 2(H20) = H2CO3 + 2(OH-)

or

(CO3)2- + (H20) = HCO3- + (OH-)

but you use an ICE table, im pretty sure on that

 

[chapz]

^ yeahh, have you dont buffers or whatever? or are you just doing pOH and -log[OH]? or have you done Ka and Kb and stuff like that>

 

[EVAN.F]

^no not really buffers, mainly just the Ka and Kb and pOH.

 

[spqr]

all I know is that your pOH is the opisite of the log of the OH concentration... that I had beat into my head in highschool.

 

[freezed]

find the OH- concentration using your ICE table, then 14 - (-log[OH-]) = pH.

 

[EVAN.F]

ok, to set up my ICE table would I use

(CO3)2- + 2(H20) = H2CO3 + 2(OH-)

or do 2 ice tables

(CO3)2- + (H20) = HCO3- + (OH-)

HCO3- + (H20) = H2CO3 + OH-

Ka1 = 4.3 x 10-7 Ka2 = 5.6 x 10^-11

I'm beginning to think which BE to use can only be answered by my teacher who wrote the question...

 

[An10a_Eng]

Henderson Hasselbach equation