chemology 08 >.<

[Martoman]

Few questions.

First question asks

CH3COOH + NaHCO3 -> NaCH3COO + CO2 + H2O

Which would best measure the rate of reaction?

a) Volume of CO2 (my choice)
b) Volume of H2O (wtf)
c) Mass of CH3COOH
d) surface area of NaHCO3..... this is their answer.



Q10) How does the oxidation number in O change from Na2O2 to O2

Oxygen's state is -1 in this? Sneaky if so.

[JinXi]

Few questions.

First question asks

CH3COOH + NaHCO3 -> NaCH3COO + CO2 + H2O

Which would best measure the rate of reaction?

a) Volume of CO2 (my choice)
b) Volume of H2O (wtf)
c) Mass of CH3COOH
d) surface area of NaHCO3..... this is their answer.



Q10) How does the oxidation number in O change from Na2O2 to O2

Oxygen's state is -1 in this? Sneaky if so.

The first one's probably cause CO2 and H20 is in the form of gas, so it's really hard to measure. Wouldn't know how to measure S.A as well though -.-

Q10)

Yeah the oxidation number of oxygen in Na2O2 is -1, cause Na2O2 is a form of peroxide, and oxygen is -1 in them.

[samiira]

With the first one i think (d) should be right because surface area is a factor that determines rate of a reaction. The more finely divided the solid is, the faster the reaction happens as it has a greater surface area.

Q10) yeh the oxidation no. of oxygen in N2O2 is -1 because it is in a peroxide form

[Martoman]

With the first one i think (d) should be right because surface area is a factor that determines rate of a reaction. The more finely divided the solid is, the faster the reaction happens as it has a greater surface area.

Q10) yeh the oxidation no. of oxygen in N2O2 is -1 because it is in a peroxide form

Just because it increases ther rate doesn't mean its a good measure of it. As JinXi said, it would be hard to measure that. I would think if you set up the system attached to a syringe measuring the rate of CO2 evolution that would give you a good indication as well as C as it will decrease. Crappy question I think.

annnddddd what is peroxide form?

[fady_22]

I have no idea what they were thinking in the first question.

For question 10), the oxidation state is -1 (the peroxide ion ).

[Martoman]

ah ok. I didn't know that ion was that

[Mao]

Few questions.

First question asks

CH3COOH + NaHCO3 -> NaCH3COO + CO2 + H2O

Which would best measure the rate of reaction?

a) Volume of CO2 (my choice)
b) Volume of H2O (wtf)
c) Mass of CH3COOH
d) surface area of NaHCO3..... this is their answer.

I agree with you. The first one is a simple acid/base neutralization. It won't be energetic enough to produce steam.
Measuring the volume of CO2 (using a syringe) is definitely the best way to calculate the rate of reaction, though it is not a direct method (dV/dt is the rate). I don't think there are good physical methods of measuring the surface area of a reagent.
However, if the question asks what is the best 'indicator'/'approximation' of the rate of reaction, it will be d).

[Mao]

Q10) How does the oxidation number in O change from Na2O2 to O2

Oxygen's state is -1 in this? Sneaky if so.

Na2O2:

Na-O-O-Na

O2:

O=O


You can see from the bonds that in the first case, O has a heteronuclear bond (Na-O) which gives it a -1. In the second case, both bonds are homonuclear and the oxidation number is 0.

[Martoman]

Few questions.

First question asks

CH3COOH + NaHCO3 -> NaCH3COO + CO2 + H2O

Which would best measure the rate of reaction?

a) Volume of CO2 (my choice)
b) Volume of H2O (wtf)
c) Mass of CH3COOH
d) surface area of NaHCO3..... this is their answer.

I agree with you. The first one is a simple acid/base neutralization. It won't be energetic enough to produce steam.
Measuring the volume of CO2 (using a syringe) is definitely the best way to calculate the rate of reaction, though it is not a direct method (dV/dt is the rate). I don't think there are good physical methods of measuring the surface area of a reagent.
However, if the question asks what is the best 'indicator'/'approximation' of the rate of reaction, it will be d).

What by seeing how much of it is disappearing by eye?

[Mao]

Few questions.

First question asks

CH3COOH + NaHCO3 -> NaCH3COO + CO2 + H2O

Which would best measure the rate of reaction?

a) Volume of CO2 (my choice)
b) Volume of H2O (wtf)
c) Mass of CH3COOH
d) surface area of NaHCO3..... this is their answer.

I agree with you. The first one is a simple acid/base neutralization. It won't be energetic enough to produce steam.
Measuring the volume of CO2 (using a syringe) is definitely the best way to calculate the rate of reaction, though it is not a direct method (dV/dt is the rate). I don't think there are good physical methods of measuring the surface area of a reagent.
However, if the question asks what is the best 'indicator'/'approximation' of the rate of reaction, it will be d).

What by seeing how much of it is disappearing by eye?

Well, the initial rate can be estimated (by measuring the SA before putting it into the solution). After that it stops being so quantitative.

[Martoman]

Yeah, whats the worth of having something not quantitative when measuring things like this in chem apart from approximation?