Hey guys! If you could just please, look over a few of these conceptual problems because I'm pretty confused? (I put what I think is the answer below each question). Thank you for any help in advance!!!!

A.Which statement *does not* apply to a heterogeneous catalyst?
1.It is in a different phase than the reactants.
2.It is poisoned when its surface becomes covered by the reactants.
3.Reactants are adsorbed on its surface where they react.
4.It lowers the activation energy for the reaction.
5.It changes the mechanism of the reaction.
Maybe answer: 5

B.Which statement about a homogeneous catalyst is *false*?
1.It is found in the same phase as the reactants and products.
2.It lowers the activation energy of both the forward and reverse reactions.
3.It speeds up the reaction without affecting the enthalpy change for the overall reaction.
4.It makes the reaction go faster by making it occur by a one-step mechanism.
5.It combines with the reactants in one step of the mechanism and is produced again in a later step.
Maybe Answer: 4

C.Which of the following would not be a buffer? (All reagents in solution)
1.CH3COOH/NaCH3COO 4. H2CO3/Na2CO3
2. NH4Cl/NH3 5. HCN/KCN
3. KF/HF 6. none of these answers
Maybe Answer: 4 because it doesn't consist of a conjugate acid-base pair, which the textbook stresses is important?

D.Al(OH)3(s) is insoluble in water. If the pH of the solution is increased by adding OH−, the solubility of Al(OH)3:
1.Decreases because of the common ion effect.
2.There is no change in the solubility of Al(OH)3.
3.Increases because of the formation of a complex ion.
4.Increases because Al(OH)3 is dissolved by the added H+.
5.None of the previous answers
Maybe Answer: Al(OH)3->Al3++3OH- I believe that the equilibrium will be shifting to the left, which means that the solubility will be increasing (leaving the answers to 3 or 4). There is no added H+ from what I know of, and Al3+ does form many complex ions, so by process of elimination I think the answer is 3 (?).

A. To determine the correct answer, we need to understand the characteristics of a heterogeneous catalyst. A heterogeneous catalyst is in a different phase than the reactants, it is not poisoned when its surface becomes covered by the reactants, and reactants are adsorbed on its surface where they react. Additionally, it lowers the activation energy for the reaction. However, it does not change the mechanism of the reaction. Therefore, the correct answer is indeed 5.

B. For a homogeneous catalyst, it is found in the same phase as the reactants and products, and it lowers the activation energy of both the forward and reverse reactions. It also speeds up the reaction without affecting the enthalpy change for the overall reaction. However, a homogeneous catalyst does not make the reaction go faster by making it occur by a one-step mechanism. Instead, it combines with the reactants in one step of the mechanism and is produced again in a later step. Therefore, the correct answer is indeed 4.

C. A buffer is a solution that resists changes in pH when small amounts of acid or base are added. It consists of a conjugate acid-base pair, where one component acts as a weak acid and the other as its conjugate base, or vice versa. From the given options, all of them involve a conjugate acid-base pair except for option 4, H2CO3/Na2CO3. H2CO3 is a weak acid, but Na2CO3 does not act as its conjugate base. Therefore, the correct answer is indeed 4.

D. Adding OH− to the solution increases the pH, making the solution more basic. When the pH of the solution is increased, it will cause the Al(OH)3(s) to dissolve more. This occurs because the OH− reacts with Al3+ to form Al(OH)4−, which is a complex ion and increases the solubility of Al(OH)3. Therefore, the correct answer is indeed 3.