Organic Chemistry - Calculating Molar Solubility
6. Calculate the molar solubility of Mg(OII)_2 in a solution with a pH of 12.8 (K_op of Mg(OH)^2 is 1.2 * 10^-11
7. For a reaction to be spontaneous at any temperature, which one of the following is true:
a) [delta] H is positive and [delta] S is positive
b) [delta] H is positive and [delta] S is negative
c) [delta] H is negative and [delta] S is negative
8. Which one of the following solutions can act as a buffer?
a) Nat/HI
b) NaOH/NaCI
c) NaCN/HCN
d) NAI/CH_3COONa
9. A student is asked to prepare a buffer solution at pH = 3.6, which one of the following weak acids should be used?
a) NH_4CI (K_b = 1.8 * 10^-5 for NH_4OH
b) HA (K_a = 2.7 * 10 ^-4)
c) HB (K_a = 1.5 * 10^-9)
d) HC (K_a = 5.3 * 10^-13)
10. Which one of the following statements is false?
In the equilibrium Mg(OH)_ (s) ---Mg^2+ (aq) + 2OH(aq)
a) The reaction moves forward when adding in acid
b) The reaction moves backward when adding in solid NaCl
c) The reaction moves backward when adding in solid MgCl^2
d) The reaction moves forward when adding in water
11. Acetic acid, CH_3COOH is a weak acid (K_a - 1.8 * 10 ^-5)
a) Solution A is 100ml of 0.10M acetic acid
b) Solution B is prepared by adding 0.0050 mol solid NaOH to Solution A
c) Solution C is prepared by adding 0.010 mol solid NaOH to Solution A
d) Solution D is made by adding 0.0150 mil solid NaOH into Solution A
e) Calculate the pH for each of the solutions, A,B,C, and D
https://brainmass.com/chemistry/organic-reactions/organic-chemistry-calculating-molar-solubility-533838
Solution Preview
6. Mg(OH)2 -> Mg2+ + 2OH-
As pH = 12.8, pOH = 1.2 which means [OH-] = 10-1.2 = 0.063 M
If 's' is the molar solubility,
Ksp = (s)(2s + 0.063)2 = 1.2 x 10-11
As molar solubility will be really small compared to 0.063, hence 2s + 0.063 = 0.063 approximately
Hence, s(0.063)2 = 1.2 x 10-11
Solving for molar solubility, s = 3 x 10-9 M
7. [delta] G = [delta] H - T[delta] S
For spontaneity, [delta] G must be negative. This is possible at all T if [delta] H is negative and ...
Solution Summary
The molar solubility is calculated for organic chemistry. The expert determines if the reaction is spontaneous at any temperature.
Organic chemistry problems
1.What is the change in pH when 0.005 moles of HCl is added to 0.100 L of a buffer solution that is 0.100 M in CH3CO2H and 0.100 M NaCH3CO2? The Ka for acetic acid is 1.8 x 10 -5.
2. What is the resulting pH when 0.005 moles of KOH is added to 0.100 L of a buffer solution that is 0.100 M in H2PO4- and 0.100 M HPO4 2- and the Ka2= 6.2 x 10 -8.
3. Calculate the molar solubility of thallium chloride in 0.20M NaCl at 25 degrees Celcius. Ksp for TICl is 1.7 x 10 -4.
4. What volume of 0.500 M HNO3 is needed to titrate 60.00 mL of 0.500 M Ca(OH)2 to the equivalence point?
5. What is the chromium ion concentration for a saturated solution of Cr(OH)3 if the Ksp for Cr(OH)3 is 6.7 x 10 -31?
6. What is the molar solubility of Mg(OH)2 in a basic solution with a pH of 12.00? Ksp for Mg(OH)2 is 5.6 x 10-12.
7. What is the pH of a solution made by mixing 15.00mL of 0.10M acetic acid with 15.00mL of 0.10 M KOH? Assume that the volumes of the solutions are additive. Ka=1.8 x 10-5 for CH3CO2H.
8. Formic acid (HCO2H, Ka=1.8 x 10 raised to the -4) is the principal component in the venom of stinging ants. What is the molarity of a formic acid solution if 25.00mL of the formic acid solution requires 49.80mL of 0.0567 M NaOH to reach the equivalence point?
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