CHEMISTRY COMMUNITY

Jane Burgan 1C

how would you solve for worksheet 10 number 2 part c and d?

Jane Burgan 1C

What are differences between intermediates and catalysts?

Jane Burgan 1C

How does temperature affect the activated complex model?

Jane Burgan 1C

Are catalysts included in the rate law of a reaction mechanism?

Jane Burgan 1C

For problems where the textbook gives us the half-life of a second order reaction of a substance and it asks us to calculate the time needed for the concentration of the substance to decrease by 1/16, why can't we just multiply the half-life by 4 to get the time needed?

Jane Burgan 1C

Why does the slowest step of the reaction mechanism determine the rate of the overall reaction?

Jane Burgan 1C

To rank elements by their reducing power, this means that the element itself is the one that's probably going to be oxidized in the reaction. You can think of it like the more reducing power an element has, the more likely it's going to be oxidized because it's giving up an electron to reduce anothe...

Jane Burgan 1C

I think one factor is the rate constant - if the rate constant k is very small, then the reaction is going to take longer but if the rate constant k is very large, then the reaction will be faster.

Jane Burgan 1C

To find the consumption rate of H2, you multiply the average rate of the reaction by 3/2, because the reaction rate has been based on creating 2 mols of NH3, but you need to find the consumption rate of 3 mols of H2. To find the unique reaction rate, you divide the average reaction rate (1.15) by 2 ...

Jane Burgan 1C

An example in the textbook asks us to calculate the potential of a Daniell cell at 25 C in which the concentration of Zn2+ ions is 0.10 mol L 1 and that of the Cu2+ ions is 0.0010 mol L 1. How do we know if Zn2+ or Cu2+ is the product or reactant?

Jane Burgan 1C

What's the difference between a first and second reaction order, and how do we determine which reaction order a reaction is?

Jane Burgan 1C

Calculate the molar concentration of Y3 in a saturated solution of YF3 by using a cell constructed with two yttrium electrodes. The electrolyte in one compartment is 1.0 m Y(NO3)3(aq). In the other compartment you have prepared a saturated solution of YF3. The measured cell potential is 0.34 V at 29...

Jane Burgan 1C

For the 6th edition for problem 14-17, it says (a) Write balanced half-reactions for the redox reaction of an acidic solution of potassium permanganate and iron(II) chloride. (b) Write the balanced equation for the cell reaction and devise a galvanic cell to study the reaction (write its cell diagra...

Jane Burgan 1C

You put the substance with the highest oxidation number in the couple in the middle of the cell diagram. So, for this problem, you would do Zn/Zn+2//Ni2+/Ni

Jane Burgan 1C

What's the difference between delta G and then deltaG^0?

Jane Burgan 1C

A question asks us to balance this skeletal equation using oxidation and reduction half-reactions, and identify the oxidizing and reducing agent. The reaction is
Cl2(g) --> HClO(aq) + Cl-(aq)
Cl2 is being reduced, so it's the oxidizing agent, but what's being oxidized in this equation?

Jane Burgan 1C

Hi can someone explain the equation G = deltaG^0 + RTlnQ? I'm not sure where the RTlnQ is coming from.

Jane Burgan 1C

Delta H is the change in enthalpy, and the definition of enthalpy is that it is heat released or absorbed under constant pressure. So, when you're given delta H you know that there's constant pressure.

Jane Burgan 1C

Before doing those two steps, you need to heat the water up from 85C to 100C, so you use the q=mcdeltaT formula, where you use the molar heat capacity of liquid water, plug in moles, plug in temperature difference. After this, you add the result to the other two values that you got in your two steps!

Jane Burgan 1C

In lecture, professor Lavelle plugged in 0 for G in the equation deltaG=deltaH - TdeltaS to figure out at what temperature is G negative. Why does this work?

Jane Burgan 1C

For worksheet 4, is the answer for 6a wrong? I did (3/2)(31.9 mol)(8.314 J/Kmol)(311.15 K) = 124 kJ. When I didn't convert the temperature from C to K I got 15.1 kJ which is the answer given in the key. We don’t have to convert it to kelvin as it is change in temperature (38-0) Don't we need to con...

Jane Burgan 1C

Why is the internal energy of an ideal gas equal to 0 when it expands isothermally and reversibly?

Jane Burgan 1C

Why is the heating slope for a liquid less steep if it has a higher heat capacity compared to a lower heat capacity that results in a steeper slope?

Jane Burgan 1C

Can someone explain what residual entropy is and why it's important?

Jane Burgan 1C

The change in internal energy is equal to q + w. In this problem, q is 0 because there's no heat given off or absorbed as energy, so the change in internal energy is just equal to w. From parts a and b, you know the work value so the change in internal energy will be equal to the work value you solv...

Jane Burgan 1C

I don't know if there will be specific questions asking us to derive the work equation and explain it using the integral, but I think it's a good idea that you understand how it relates to the work equation because then you'll probably be more comfortable using the work equation to solve problems.

Jane Burgan 1C

An example of an isolated system would be a thermos because no energy or heat can be exchanged with the surroundings because the walls are thermally insulated (no heat), and the volume is constant (no energy as work).

Jane Burgan 1C

For the water heating curve, when water is changing from solid to liquid form and from liquid to vapor form, the temperature remains constant. Even though the extra heat is being used to break down the bonds between the molecules, why isn't there at least a slight increase in temperature?

Jane Burgan 1C

Is there a difference when the question asks what happens to the equilibrium composition if the partial pressure of one reactant is increased versus if the overall pressure is increased?

Jane Burgan 1C

The question asks us to calculate the pH of a .055 M solution of AlCl3(aq). The solutions manual shows the equation to be Al(H20)6 + H20 -- H30 + Al(H20)5OH
How do we know to use Al instead of Cl and to combine Al with H2O?

Jane Burgan 1C

Changing the concentration of reactants and products don't change K because K is a constant - the ratio of products to reactants. When the concentration of the reactant is changed, then the reaction shifts in the direction of the products until the original ratio of P to R is restored. When the conc...

Jane Burgan 1C

I can't really tell what the equations are because it looks like the computer keyboard may have messed them up haha but I think for a it's reactants because there are more moles of gas on the right side of the reaction. In general for these problems, you can figure them out by this rule : if there a...

Jane Burgan 1C

I understand why if there are more moles of gas on the left side of a reaction, then the reactions shifts right if pressure is added. But, why does the reaction shift left if pressure is added and there are moles of gas on the right?

Jane Burgan 1C

For 11.43 in the 6th edition, the question says: Consider the reaction 2 NO(g) -- ∆ N2(g) + O2(g). If the initial partial pressure of NO(g) is 1.0 bar, and x is the equilibrium concentration of N2(g), what is the correct equilibrium relation? Why can't the answer be k = x^2/(1.0-x)^2, why is it k=x^...

Jane Burgan 1C

If K is greater than 10^3, that means the products are favored - there is a higher concentration of products compared to that of reactants at equilibrium. When K is less than 10^-3, that means the reactants are favored - there is a higher concentration of reactants compared to that of products at eq...

Jane Burgan 1C

There's no net change in the concentration of reactants and products and the forward and reverse reactions are happening at the same rate

Jane Burgan 1C

Pressure doesn't change the equilibrium constant it only changes the position of equilibrium. Temperature does affect K. When the forward reaction is endothermic, increasing the temperature increases the value of K. When the forward reaction is exothermic, increasing the temperature decreases the va...

Jane Burgan 1C

For small, highly charged cations that have greater polarizing power, do we look at the size or the charge of the cation first to determine its polarizing power? For example, if we’re comparing Be2+ and Li+, which one has more polarizing power? Is it Li+ because it’s smaller or Be2+ because it’s mor...

Jane Burgan 1C

what is the difference between pKa, pKb, Ka, and Kb?

Jane Burgan 1C

Calculate the initial molarity of Ba(OH)2 and the molarities of Ba2 , OH , and H3O in an aqueous solution that contains 0.43 g of Ba(OH)2 in 0.100 L of solution.
How do you do this problem?

Jane Burgan 1C

What's the difference when you're calculating the pH of a strong versus a weak acid? I'm very confused with the Ka and the pKa equilibrium and how to calculate the pH when you're given a certain number of grams of a molecule and the molarity of it in a solution.

Jane Burgan 1C

The concentration of HCl in hydrochloric acid is reduced to 12% of its initial value by dilution. What is the difference in the pH values of the two solutions?

How do you figure out this problem?

Jane Burgan 1C

How do you know when to write OH2 versus H2O when writing the formula given the coordination compound?

Jane Burgan 1C

How do you figure out the oxidation number of coordination compounds?

Jane Burgan 1C

What's the importance of a chelate and are they stronger than normal coordination compounds?

Jane Burgan 1C

The textbook says that if a ligand is polydentate, then use the bis, tris, and tetrakis prefixes instead. How do you know if a ligand is polydentate?

Jane Burgan 1C

Predict which would have a higher boiling point: HBr or HI. I thought HBr has higher boiling point compared to HI, because Br is smaller than I, meaning that the bond length between H and Br is shorter and stronger, so it would be harder to break this bond. But, the answer is HI. Can someone explain...

Jane Burgan 1C

Will we be given the electronegativities of the two atoms so that we can calculate the difference? Or is it more of an estimate based on where the atoms are on the periodic table?

Jane Burgan 1C

Why is the shape of an i3- ion linear not angular? Don't the two lone pairs on top of the central iodine repel the other two iodine atoms from being attached in a straight line to the central iodine to bent?

Jane Burgan 1C

State the hybridization of the atom in boldface type in each
of the following molecules: (a) BeCl2 (Be boldface); (b) BH3 (B boldface); (c) BH4 (B boldface); (d) SiF4 (Si boldface).

How do you do this problem?

Jane Burgan 1C

When you're given isomers of a compound, how do you determine which one has the largest dipole moment?

Jane Burgan 1C

Which type of bond is stronger - a sigma bond or a pi bond?
Also, the textbook had this little chart:
A single bond is a sigma-bond. A double bond is a sigma-bond plus one pi-bond. A triple bond is a sigma-bond plus two pi-bonds.
Can someone explain this?

Jane Burgan 1C

Since polarizability is when atoms and ions have electron clouds that easily undergo large distortion, larger atoms are more polarizable compared to smaller atoms. So, polarizability increases going down a group, but decreases going across a period. When you go down a group, there are more shells be...

Jane Burgan 1C

I wasn't sure of this question either so as I was looking up different information I found this question was asked in an older chemistry community post! Here's the link :)

viewtopic.php?t=1248

Jane Burgan 1C

For each pair, determine which compound has bonds with greater ionic character: (a) HCl or HI; (b) CH4 or CF4;
(c) CO2 or CS2.

How do you tell which compound has greater ionic character?

Jane Burgan 1C

Cr and Cu are exceptions to the ground state electron configurations rules. Normally, you would expect Cr to be [Ar]3d^4s^2, but it's actually [Ar]3d^54s^1. The reason why is because the Cr is more stable having 5 electrons in its d-orbital because then it's a half-filled subshell, compared to just ...

Jane Burgan 1C

Ionization energy is the energy it takes to remove an electron from an atom. The periodic table trends are that ionization energy decreases going down a group because the electrons are farther away from the nucleus so there's less charge pulling them in and the other electrons create a shielding eff...

Jane Burgan 1C

Technically both ways are correct! It's just much easier to write the abbreviated version with the last noble gas filled and then the remaining orbitals because it saves space and time. It's most common to write it the second way and Lavelle usually writes electron configurations that way in lecture...

Jane Burgan 1C

Since the metal is M^3+ you know that the metal has lost 3 electrons which will help you when trying to figure out what the metal is. a. You're given [Ar]3d^6 after the metal has lost 3 electrons. Remember that the 4s orbital is written after the 3d orbital in electron configuration form because it ...

Jane Burgan 1C

the 4f14 and the 5s4 would come before the 6s2 because they both have lower energy levels than the 6s orbital. When determining the order of the orbitals for the electron configuration think of the orbitals' energy levels. In this case, 4f14 has a lower energy level than 5s2 and 5s4 has a lower ener...

Jane Burgan 1C

The Lyman series for the hydrogen atom is known to lie in the ultraviolet spectrum and its principle quantum energy level is n1=1, so for this problem since the line is observed in the ultraviolet spectrum, you can apply the fact that the Lyman series is n1=1.

Jane Burgan 1C

Since you're given the amount of sodium in mg, convert this amount into moles by dividing 5.00 mg by the molar mass of sodium. Once you have the amount of sodium in moles, you can multiply this number by avogrado's number to get the number of sodium atoms in 5.00 mg. Finally, multiply your answer by...

Jane Burgan 1C

What is the minimum uncertainty in the speed of an electron con ned to within a lead atom of diameter 350. pm? Model the atom as a one-dimensional box with a length equal to the diameter of the actual atom. How do you model the atom? Is it just a box with a labeled length of 350.pm? Or do we add the...

Jane Burgan 1C

(b) How many values of ml are allowed for an electron in a 5f-subshell? (c) How many values of ml are allowed for an electron in a 2s-subshell? I don't understand the answers in the solutions manual. For part b, I thought n=5, l=3 since it's an f orbital, so then the values of ml could be -3, -2, -1...

Jane Burgan 1C

You would first find the number of moles of sodium atoms that 5.00 mg contains by dividing 5.00 mg by sodium's molar mass, then multiply that value by avogardo's number because that would transform the number of moles to the number of atoms that 5.00 mg of NA is. Finally, multiply that value by the ...

Jane Burgan 1C

I think these are the only modules that he has made. I'm not 100% sure but he probably would have put all the modules he had up on his website no matter the unit we're on. Maybe your TA knows?

Jane Burgan 1C

23. You are caught in a radar trap and hope to show that the speed measured by the radar gun is in error due to the Heisenberg uncertainty principle. If you assume that the uncertainty in your position was +/- 5 m when your speed was measured, and that the car has a mass of 2150 kg, what is your cal...

Jane Burgan 1C

It depends on the information given in the question. If the original or diluted solution volume is given in mL, then use mL. But, if it's given in L use L. Usually though they'll specify and if not, you can use L!

Jane Burgan 1C

Molybdenum metal must absorb radiation with a minimum frequency of 1.09 x 10^15 s-1 before it can emit an electron from its surface. If molybdenum is irradiated with 194 nm light, what is the maximum possible kinetic energy of the emitted electrons? I'm pretty sure we have to solve the problem using...

Jane Burgan 1C

When an electron drops from a higher energy level to a lower energy level, why isn't the energy given off positive? Why is negative? Because wouldn't it have extra energy that can be given off now that it's going down?

Jane Burgan 1C

How do you figure out the formulas of polyatomic ions besides memorizing them?

Jane Burgan 1C

A chemist measured out 8.61 g of copper(II) chloride tetrahydrate, CuCl2 * 4H2O. (a). How many moles of CuCl2 * 4H2O were measured out? (b). How many moles of Cl- ions are present in the sample? (c). How many H2O molecules are present in the sample? (d). What fraction of the total mass of the sample...

Jane Burgan 1C

@katie you can find a solutions manual for the 6th edition on amazon and the 7th edition on textbooks.com! Also for the module there aren't solutions but u can always ask about a specific question in the module here and people will reply with step by step solutions and help :)

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