NH3 is a weak base (Kb = 1.8 105) and so the salt NH4Cl acts as a weak acid. Wha
ID: 790451 • Letter: N
Question
NH3 is a weak base (Kb = 1.8 105) and so the salt NH4Cl acts as a weak acid. What is the pH of a solution that is 0.090 M in NH4Cl?I got as far as the -log and got 5 something but i don't know if that's right.. i thought i had to subtract it and when i did i still got the wrong answer... thanks!@
NH3 is a weak base (Kb = 1.8 105) and so the salt NH4Cl acts as a weak acid. What is the pH of a solution that is 0.090 M in NH4Cl?
I got as far as the -log and got 5 something but i don't know if that's right.. i thought i had to subtract it and when i did i still got the wrong answer... thanks!@
NH3 is a weak base (Kb = 1.8 105) and so the salt NH4Cl acts as a weak acid. What is the pH of a solution that is 0.090 M in NH4Cl?
I got as far as the -log and got 5 something but i don't know if that's right.. i thought i had to subtract it and when i did i still got the wrong answer... thanks!@
NH3 is a weak base (Kb = 1.8 105) and so the salt NH4Cl acts as a weak acid. What is the pH of a solution that is 0.090 M in NH4Cl?
I got as far as the -log and got 5 something but i don't know if that's right.. i thought i had to subtract it and when i did i still got the wrong answer... thanks!@
Explanation / Answer
NH4Cl Ka =Kw/Kb = 1E-14/1,8E-5= 5.56E-10
The NH4Cl dissociates completely and then the NH4+ reacts with water according to Ka
NH4+ +H2O-----> NH3 + H3O+
[NH3][H3O+]/[NH4+]=5.56E-10 H3O+ is the conjugate acid and controls the pH
NH3 and H3O+ are equal but ubknown so the both equal X and are insignificant to 0.031 so no subtraction from 0.031 is necessary
X^2/[0.09]=5.56E-10
X^2=0.2E-11
X=2.236E-6 = H3O+ or H+ so pH=-log[H+]
pH = 5.65
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