CHEMISTRY COMMUNITY

Chloe1K

For concentration cells, which concentration goes at the anode, the lower or higher one? Why?

Chloe1K

What does it mean when the textbook questions say "in practice, the new pathway also has a different pre-exponential factor"? If this means that A for the new pathway with the catalyst changes, how does it cancel out when we try to find Ea?

Chloe1K

is the only way to find out whether this is endothermic or exothermic by using the equation ∆G° = -RTlnK? How else would you be able to do this as this is thermodynamics?

Chloe1K

can you answer this question only in terms of activation energies?

Chloe1K

when it asks to rank the following elements in order of increasing reducing power, is this the same as ranking their ions in order of increasing reducing power? This question confused me because when you reverse the equations the sign of the standard potentials reverse too, and the answers were base...

Chloe1K

I think the book just gave a random increase to concentration to show that if rate increases by the same factor it is a first order reaction.

Chloe1K

it means that when you change the concentration, it does not have an effect on the rate.

Chloe1K

the concentration will appear in the denominator of the rate law. increasing the concentration would slow down the reaction because the negative order means it favors the reverse reaction.

Chloe1K

it's a positive value for b) because when you're finding the rate of the products (formation of O2), it's + 1/c ΔC/Δt.

Chloe1K

I don't think we've discussed how this works yet but it does! The exact reasons for this are quite technical and relate to the concept of standard states. In the end, if you want to use a "mixed" equilibrium expression, containing both concentrations and pressures, then the pressures must ...

Chloe1K

never mind, I just realized that the electron transfer is 2 not one :/

Chloe1K

for part b, I keep getting lnk = 4.67 which leads to a k value of 110, which is different to the textbook solution. Could someone please explain how they did this question?

Chloe1K

What does it mean when it asks whether Tl3+ will disproportionate in the solution?

Chloe1K

electrolysis: an electric current drives a chemical reaction that will separate an ionic substance. I don't think I saw it on the syllabus though so I don't know if we'll be learning about it.

Chloe1K

because standard reduction potentials (E°)are intensive properties, they stay the same even when balanced so moles don't matter. however if the reduction half equations are reversed don't forget to change the sign of E°

Chloe1K

thank you!

Chloe1K

you can also think of this in terms of equilibrium: exothermic reaction: reactants --> products +heat - if temperature is lowered, heat decreases, and in order to maintain equilibrium more products will be formed. endothermic reaction: reactants + heat --> products - if temperature is increased, hea...

Chloe1K

When a phase change occurs temperature (x axis) stays constant, while entropy (y axis) will keep increasing, causing a vertical line.

Chloe1K

Can someone please explain which equations to use for this question and why?

Chloe1K

no change in pressure means ∆P=0, not P=0. the equation for work uses P not ∆P and it is unlikely P=0

Chloe1K

what is an example of a conceptual question in terms of internal energy?

Chloe1K

the products would leave via the exhaust pipe into the surroundings and the reaction would heat up the surroundings as well. both matter and energy can be exchanged with surroundings so it is an open system

Chloe1K

Can someone please explain why the answer to 8.43 is c, not b? thank you!!

CHEMISTRY COMMUNITY

Search found 23 matches

Cell Diagrams for Concentration Cells

16.69: Pre exponential factor in catalysis

16.65 part b

Re: 15.65, part c

Test 2 Q5

Re: 15.15

Re: Zero Order Reactions and Rate of Reaction

Re: Negative order

Re: 15.3 C

Re: 14.43

Re: 14.35

Re: 14.35

14.33

Re: Electrical energy to chemical energy

Re: Standard Reduction Potential

Re: 9.7

Re: Exothermic/Endothermic

Re: Entropy Phase Change

9.7

Re: Internal Energy

Re: Week 3 Test Topic is endorsed

Re: HW 8.1

Question 8.43