1) Determine the molar solubility of BaF2 in pure water. Ksp for BaF2 = 2.45 x 1
ID: 835640 • Letter: 1
Question
1) Determine the molar solubility of BaF2 in pure water. Ksp for BaF2 = 2.45 x 10^-5.
2) Define buffer capacity.
Buffer capacity is the amount of acid or base that can be added to a buffer without destroying its effectiveness.
Buffer capacity is the amount of acid that can be added until all of the base is used up.
Buffer capacity is the amount of base that can be added until all of the acid is used up.
Buffer capacity is the amount of acid that can be added until all of the acid is used up.
e. Buffer capacity is the amount of base that can be added until all of the base is used up.
3) Identify the indicator that can be used at the lowest pH.
alizarin
thymol blue
crystal violet
phenolphthalein
alizarin yellow R
4) Which of the following is NOT true for ?Grxn?
If ?G
a.Buffer capacity is the amount of acid or base that can be added to a buffer without destroying its effectiveness.
b.Buffer capacity is the amount of acid that can be added until all of the base is used up.
c.Buffer capacity is the amount of base that can be added until all of the acid is used up.
d.Buffer capacity is the amount of acid that can be added until all of the acid is used up.
e. Buffer capacity is the amount of base that can be added until all of the base is used up.
3) Identify the indicator that can be used at the lowest pH.
a.alizarin
b.thymol blue
c.crystal violet
d.phenolphthalein
e.alizarin yellow R
4) Which of the following is NOT true for ?Grxn?
a.If ?G
Explanation / Answer
1)in pure water :
BaF2 (s) <-------> Ba(2+) (aq) + 2F(-) (aq)
let the solubility of BaF2 be s moles/L ...the the solution will contain s moles of Ba(2+) and 2s moles of F(-) ions respectively per litre ...hence the solubility product Ksp of BaF2 would be given by the expression :
Ksp = [Ba2+] [F-]^2
Ksp = s(2s)^2 = s X 4s^2 = 4s^3
but the given value of Ksp is 2.45 X 10^-5
so 4s^3 = 2.45 X 10^-5
s^3 = 2.45 X 10^-5/4 = 6.125 X 10^-6
s = 1.83 X 10^-2 mole/L
2)
Buffer capacity is the amount of acid or base that can be added to a buffer without destroying its effectiveness.
3)
crystal violet
4)a. If delta G is positive, the reaction is nonspontaneous because work must be supplied from the surroundings to make it occur
a.Buffer capacity is the amount of acid or base that can be added to a buffer without destroying its effectiveness.
3)
c.crystal violet
4)a. If delta G is positive, the reaction is nonspontaneous because work must be supplied from the surroundings to make it occur
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