CHEMISTRY COMMUNITY

Athena L 1B

So is a bimolecular reaction another way of saying it's second order?

Athena L 1B

The hill - looking thing that comes after the reactants in energy diagrams represents the activation energy

Athena L 1B

Also, the units for k are specific to each reaction, so you have to find those separately too

Athena L 1B

If you plot any of those graphs but get a curve, you know you have the wrong order reaction

Athena L 1B

can that tell you anything about the rate of the reaction?

Athena L 1B

When you are given something like H+ and H2 with Ni2+ and Ni, how do you know which pair is the cathode and which is the anode?

Athena L 1B

Is Pt(s) the only other substance you would add in any scenario?

Athena L 1B

In the equation G= -RTlnK, the free energy clearly depends on K, but I'm not as sure about the pressure part. Temperature and pressure are proportional to each other by PV=nRT, so maybe that's the connection you're supposed to make?

Athena L 1B

I think it is a series of elements arranged in order of their reduction potentials

Athena L 1B

Can you post the question?

Athena L 1B

I think it is different because it's specifically the E of the cathode and anode

Athena L 1B

The more negative the E value, the stronger it is as a reducing agent, so the more positive the E value, the stronger it is as an oxidizing agent.

Athena L 1B

Closed systems can transfer only energy, and open systems can transfer energy and matter

Athena L 1B

What sections is the homework for this week supposed to be on?

Athena L 1B

What was the problem for this one?

Athena L 1B

If you are not given a temperature, are you supposed to assume that it is 298K? Or does the temperature always have to be given?

Athena L 1B

The reaction of 1.40 g of carbon monoxide with excess water vapor to produce carbon dioxide and hydrogen gases in a bomb calorimeter causes the temperature of the calorimeter assembly to rise from 22.113°C to 22.799°C. The calorimeter assembly is known to have a total heat capacity (calorimeter cons...

Athena L 1B

I'm slightly confused since we have been going out of order in lecture. Which of the sections in the 7th edition textbook have we covered?

Athena L 1B

the per mole unit refers to the "formation" part: standard enthalpy of formation is the change in enthalpy that occurs when one mole of the substance is formed, so it is enthalpy per mole, or joules per mole

Athena L 1B

It was actually that PdeltaV is significant for changes in the number of moles of gas, but it is INsignificant for reactions involving solids and liquids because there is too small of a volume change for solids and liquids to account for it in the PdeltaV expression.

Athena L 1B

If we have the equations U = q + w, q = H, and w = PV, why does U = H - PV, instead of U = H + PV?

Athena L 1B

Since (delta U) = (delta H) - P(delta V), if there is no change in volume (which there isn't when you're going from a solid to a liquid), P(delta V) = 0. Therefore, delta U = delta H.

Athena L 1B

Delta Hf can be found by dividing delta H by the number of moles

Athena L 1B

I don't think there is a difference, I think the SI units for both are in joules

Athena L 1B

Can someone explain this question? A reaction mixture that consisted of 0.400 mol H2 and 1.60 mol I2 was introduced into a flask of volume 3.00 L and heated. At equilibrium, 60% of the hydrogen gas had reacted. What is the equilibrium constant K for the reaction H2(g) + I2(g) <=> 2HI(g) at this temp?

Athena L 1B

A reaction vessel of volume 0.500 L at 700. K contains 1.20 mmol SO2(g), 0.50 mmol O2(g), and 0.10 mmol SO3(g). At 700. K, Kc = 1.7 x 10^6 for the equilibrium 2SO2(g) + O2(g) <=> 2SO3(g). a) Calculate the reaction quotient b) will more SO3(g) tend to form?

Athena L 1B

So percentage ionization of an acid is the same as percentage deprotonization?

Athena L 1B

You still calculate them the same way right?

Athena L 1B

So if it was a strong acid, no you wouldn't add it to pH 7, that's only for very weak acids that don't really affect the pH at all

Athena L 1B

Can someone explain how to do number 11? I'm not sure if I'm just making calculation errors or if I am doing the problem fundamentally wrong but I can't seem to get the right answer.

Athena L 1B

Yeah he said that ONO is nitrito

Athena L 1B

Some examples of strong bases using from group 1 and group 2 are CaO, Na2O, and Li2O.

Athena L 1B

so water is amphoteric and amphiprotic

Athena L 1B

It doesn't have to have more than 4 bonding sites, it just has to have two or more to be polydentate.

Athena L 1B

Can something be an amphoteric compound, acting as an acid and a base, without being amphiprotic? Can it be an acid and base by donating and accepting lone pairs, not protons?

Athena L 1B

If it's a coordination compound that overall is neutral, but the complex is negative you still add ate to the end

Athena L 1B

A chelate is formed by ligands and makes a ring

Athena L 1B

For 6C.17, it gives two acids and you have to decide which is stronger. For c-f, how can you tell which is stronger? (The problems are c. HBrO2 vs HClO2, d. HClO4 vs H3PO4, e. HNO3 vs HNO2, f. H2CO3 vs H2GeO3)

Athena L 1B

The Lewis definition is a more general definition, as some compounds can be Lewis bases but not Bronsted bases

Athena L 1B

You can tell by looking at if there are free lone pairs on the coordination compound

Athena L 1B

How do you know when to change the ends of parts of the name? Like cynaide to cyano or other changes?

Athena L 1B

You can also get an induced dipole from a non dipole: this is the induced dipole - induced dipole interaction. The way I understand it is because electrons are really always moving around, there are times when some parts of a non-dipole molecules are partially charged in some areas, which can affect...

Athena L 1B

Also, what is the difference between polarizing power and polarizability?

Athena L 1B

Is its value always negative, or is that just for attractive forces?

Athena L 1B

The bonds don't just have the electrons added to get an octet, they have all of the electrons, including the valence electrons N already has. It's not limited to 3 to add on to the 5 valence electrons, you have to have the full octet in the bonds including the original 5. With two electrons being sh...

Athena L 1B

Once you get into elements beyond period 3, they can have more than 8 electrons because of the d orbital, allowing for expanded octets

Athena L 1B

In problem 2A, you have to write out the ground state electron configuration of (b)Bi3+ and (d)Tl3+. How do you know that you have to include the f orbital for these? I mostly get electron configurations except for when it gets to the f orbital, and then I'm not sure how it works

Athena L 1B

What does the p actually refer to?

Athena L 1B

and the fourth quantum number, ms, is either +1/2 or -1/2, and determines whether the electron is spin up or spin down

Athena L 1B

It's also basically the same trend as electronegativity.

Athena L 1B

Is De Broglie's equation the one that cannot be used for photons because it only applies to things with mass?

Athena L 1B

If you ever needed to, you would just need to multiply the hertz by something that has units J x s, which planck's constant has.

Athena L 1B

In some of the quantum problems, they list l as a variable, but I can't find what l actually means. (l is lowercase L here) Does anyone know what it means?

Athena L 1B

The work function also depends on the metal being tested - different metals have different work functions, or minimum amount of energy needed to remove an electron from the surface.

Athena L 1B

In the uncertainty principle, the units of x are distance (m). What does this actually mean for the position? Is the length just a range of where it could be?

Athena L 1B

Today in lecture we went through a problem where the change in E was negative because an electron went from a higher energy level to a lower energy level. I understand why that is negative, but then when we went on to find the frequency (using E=hv), we made E positive. I also understand that freque...

Athena L 1B

G5: A student prepared a solution of sodium carbonate by adding 2.111 g of the solid to a 250.0 mL volumetric flask and adding water to the mark. Some of this solution was transferred to a buret. What volume of solution should the student transfer into a flask to obtain (c) 50.0 mg of Na2CO3? I unde...

Athena L 1B

For question E29(c):

A chemist measured out 8.61 g of copper(II) chloride tetrahydrate, CuCl2 4H20.
(c) How many H20 molecules are present in the sample?

I got the other parts of the question (a,b,d) but now I'm blanking on how to go about this particular part.

Athena L 1B

I'm not sure what to do for this question: A solution is prepared by dissolving 0.500g of KCl, 0.500 g of K2S, and 0.500 g of K3PO4 in 500mL of water. What is the concentration in the final solution of (a) potassium ions, (b) sulfide ions? I started by converting the grams to moles but I don't know ...

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