Which of the following is correct/incorrect?

[PopcornTime]

1. A catalyst increases the rate of a reaction.
2. All catalysts are solids.
3. The mass of a catalyst is the same before and after the reaction.
4. A catalyst lowers the enthalpy change of a reaction, enabling more particles to have sufficient energy to successfully react.
5. A catalyst increases the value of the equilibrium constant, thus favouring the extent of the forward reaction, resulting in a greater yield of product.
6. All catalysts align the reactant particles in an orientation that is favourable for a reaction to occur.
7. The effectiveness of a metal catalyst is not dependent upon its surface area.
8. Enzymes are biological catalysts that catalyse a specific biochemical reaction once only.
9. The effectiveness of an enzyme is independent of temperature.

[PhoenixxFire]

How about you give it a try first. What do you think is right or wrong?

[PopcornTime]

1. A catalyst increases the rate of a reaction. True
2. All catalysts are solids. No
3. The mass of a catalyst is the same before and after the reaction. Yes
6. All catalysts align the reactant particles in an orientation that is favourable for a reaction to occur. Not too sure about this one!
7. The effectiveness of a metal catalyst is not dependent upon its surface area. Yes.
8. Enzymes are biological catalysts that catalyse a specific biochemical reaction once only. No (but could someone provide an explanation)
9. The effectiveness of an enzyme is independent of temperature. Yes

Thanks

[PhoenixxFire]

1. True
2. No
3. Yes
4.This is worded weirdly, i think its saying that it lowers the activation energy, which is true.
5. Not sure on this, way too much chemistry for me.
6. I don't know much about this, but they would definitely have to be in a position where the substrate could react, and the catalyst will bind to a particular part of the substrate so it makes sense that this would be true.
7. From the quick google i just did i think this is false.
8. No. Enzymes are biological catalysts (they catalyse biological reactions) and they only catalyse a specific biochemical pathway, however as they are not used up in the reaction, they can catalyse the same pathway multiple times.
9. No. This statement is saying that regardless of the temperature, the enzyme will work at the same rate. This is not true, as you heat up a mixture, the molecules in it move faster, increasing the rate of reaction. It continues increasing as temperature increases until it exceeds its optimal temperature, where the enzyme starts to denature, which can be permanent if heated high enough.

If this is for 3/4 bio, you don't need to know anywhere near this much detail.

Edit: fixed broken code

[Vaike]

If this is for 3/4 bio, you don't need to know anywhere near this much detail.

Definitely agree with PhoenixxFire's assessment; this question is actually from the 2013 chemistry exam, and hence covers enzyme's in a more chemically orientated fashion than is taught it the biology course.

However, some of the information is still useful for VCE biology (navy blue text is strictly chemistry knowledge; you do not need to know this):

• True. Catalysts typically increase the rate of reaction by providing an alternate reaction pathways with a lower activation energy, resulting in a higher proportion of collisions being successful.
• False. Catalysts can also exist as liquids, gases and aqueous solutions.
• True. Catalysts, such as enzymes, are unchanged during the catalysis of reaction. Hence, after the substrate has exited the enzyme/surface of catalyst, the weight should not have changed.
• False. Catalysts lower the activation energy of a given reaction, not the enthalpy change, which remains constant.
• False. Catalysts do not alter the equilibrium constant.
• False. Whilst enzymes and solid catalysts do align particles in favourable orientations, however liquid and gaseous catalysts do not.
• False. The reaction involving a metal catalyst will occur at it's surface. Hence, a larger surface area provides more catalyst area for reaction to occur, increasing 'effectiveness' of the catalyst.
• False. Enzymes can be used multiple times; they are not permanently altered during the reaction.
• False. The effectiveness of an enzyme is directly related to temperature; low temperatures result in decreased enzyme activity due to reduced collision frequency and energy, whereas high temperatures decrease enzyme activity due to denaturation of tertiary structures, permanently altering the conformation of the active site.