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 (?).
2 answers