Hi!Could someone help me?

Is H2O2 (in solution , with no additives added ) basic ,neutral or acidic?What would be (theoretically) the pH of a 0.3M solution of H2O2 , considering that it reacts with water , forming the equilibrium #H_2O_2+H_2O=H_3O^{+}+HOO^{-}#

1 Answer
Michael
Mar 11, 2018

Very slightly acidic. #sf(pH=6.1)#

Explanation:

Set up an ICE table based on #sf("mol/l")#:

#sf(" "H_2O_2+H_2OrightleftharpoonsH_3O^++HOO^-)#

#sf(Icolor(white)(xxx)0.3color(white)(xxxxxxxxxx)0color(white)(xxxxxxx)0#

#sf(Ccolor(white)(xx)-xcolor(white)(xxxxxxxx)+xcolor(white)(xxxxx)+x)#

#sf(Ecolor(white)(x)(0.3-x)color(white)(xxxxxxxx)xcolor(white)(xxxxxxx)x#

#sf(K_a=([H_3O^+][HOO^-])/([H_2O_2])=2.4xx10^(-12))#

#:.##sf(x^2/(0.3-x)=2.4xx10^(-12))#

Because the value of #sf(K_a)# is so small we can assume that #sf((0.3-x)rArr0.3)#.

#:.##sf(x^2/0.3=2.4xx10^(-12))#

#sf(x=H_3O^+=8.485xx10^(-7)color(white)(x)"mol/l")#

#sf(pH=-log[H_3O^+]=-log[8.485xx10^(-7)]=6.1)#

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