# CHEMISTRY!!!=0

posted by .

Determine pH of each solution:

0.20 M KI

i don't know how you know if you use..
K+H2O->KOH + H
or...
I- +H2O--> HIO +H

Im thinking this one...

I- + H2O --> HIO + H
0.20M--------------------0-----------0
0.20-x------------------x-------------x

there is a Ka value for HIO so that is why i made it a product...right? Ka HIO= 2.3X10^2

so..

2.3X10-11 = x^2/ 0.20-x

then do pH.. would that be correct?
so pH=5.7 ?

• CHEMISTRY!!!=0 -

You don't use either because neither K^+ nor K^- hydrolyze. You can TRY to write the equations like this;
K^+ + HOH ==> KOH + H^+ but when you go to look up Kb for KOH you realize it has no Kb because it is 100% ionized.
Then I^- + HOH ==> HI + OH^- and you look up Ka for HI but you quickly realize HI has no Ka because it is a strong acid (100% ionized). Therefore, when KI dissolves in water it is the salt of a strong acid (HI) and a strong base (KOH), neither has a Ka nor Kb so you have the salt dissolved in water and the pH = 7.0 for pure water. Technically, it won't be quite 7.0 because of activity coefficients but you haven't studied that yet.
Back to your former question, another good way to know is you look at the equation you just wrote with water; i.e.,
CH3NH3^+ + H2O ==>H3O^+ + CH3NH2
so you know to use Kb for the base sitting there on the product side.
If you have a base like acetate, then
C2H23O2^- + HOH ==> HC2H3O2 + OH^- and you know to look up the Ka value for HC2H3O2, acetic acid, since that's the acid sitting there.

• CHEMISTRY!!!=0 -

OH, okay so when I produce a strong acid and a strong base it is neutral so pH=7. Meaning the 0.20M KI doesn't even matter?

• CHEMISTRY!!!=0 -

That's right. At least for now since you haven't studied the effects of activity coefficients.

## Similar Questions

1. ### Chemistry

i need help. Calculate the pH of a 0.24 M CoCl3 solution. The Ka value for Co(H2O)63+ is 1.0 10-5. how do u do these with like the Cl there?
2. ### Chemistry

The question says write a reaction for the ionization of the following compound in water. Identify the acid, the base, the conjugate acid, and the conjugate base in each of them. 1. H2SO4 2. KOH 3. CH3COOH 4. NH3 5. HNO3 My guesses …
3. ### Chemistry

Determine the boiling point elevation of H2O in each of the following solutions: 1)2.5 m solution of C6H12O6 (glucose)in H2O. 2) 3.20 g C6 H12 O6 in 1.00 kg H20 3) 20.0 C12 H22 O11 (sucrose) in 500.g H2O
4. ### chemistry

what is the Molarity (M) of a 0.87m aqueous solution of ammonia, NH3?
5. ### CHM

Need help please Which of the following equations has the coefficients 2,1,1,2 when it is balanced?
6. ### chemistry

In the following options which one is maximum/highly exothermic reaction..?
7. ### chemistry

Determine the limiting reactant for this reaction if 3.027 grams of Aluminum are reacted with 60.00 mL of a solution that is 6 M KOH. Determine the amount of KAl(SO4)2•12 H2O that can be produced from this reaction. Molar mass Alum …
8. ### Chemistry

An aqueous antifreeze solution is 40.0% ethylene glycol (C2H6O2) by mass. The density of the solution is 1.05 g/cm3. Calculate the molality, molarity, and mole fraction of the ethylene glycol. molality I actually can do this whole …
9. ### Chemistry

A sample of g 0.2050 oxalic acid (4.2 H2C2O H2O) required 25.52 mL of KOH solution to complete the neutralization according to rea tion: HOOCCOOH + 2 KOH + KOOCCOOK ↔ H2O Which the concentration in mol L-1 of this KOH solution?
10. ### Chemistry

1.The pH of a 0.10 mol/L aqueous solution of Fe(NO3)3 is not 7.00. The equation that best accounts for this observation is: a. Fe3+(aq) + 3H2O(l)<-->Fe(OH)3(aq) + 3H+(aq) b. NO3-(aq) + H2O(l)<-----> HNO3(aq) + OH-(aq) c. …

More Similar Questions