CHEMISTRY COMMUNITY

Rakhi Ratanjee 1D

What is the equipartition theorem?

Rakhi Ratanjee 1D

What is the leaving group in a substitution reaction?

Rakhi Ratanjee 1D

Generally, the activation energies for a forward and reverse reaction will be different if the reaction is not at equilibrium because one reaction will be endothermic and the other will be exothermic, so each side requires a different amount of energy.

Rakhi Ratanjee 1D

Also, how do you know between Step 1 and Step 3 which step is faster?

Rakhi Ratanjee 1D

For 15.79 part A, the answer states that CH3CH=CHCH2Br is the product because "the positive charge on the reactive intermediate is on a primary carbon atom". How can you determine that it is a product of higher temperature from this information?

Rakhi Ratanjee 1D

Do we have to know about buffer solutions and how to find their voltage for the final?

Rakhi Ratanjee 1D

How do you read a cell diagram from left to right? On the anode side and cathode side, how do you know which molecules are the reactants and products?

Rakhi Ratanjee 1D

One of the practice problems states: "Which requires more heat: 1 mol H2(g) or 1 mol butane (g). How are we supposed to figure out which one requires more heat?

Rakhi Ratanjee 1D

Some of the thermodynamic equations have log Q and some have ln Q. Are these functions interchangeable or do we just have to apply whichever function the equation specifies?

Rakhi Ratanjee 1D

During lecture, he mentioned that the steady-state approach assumes a constant intermediate concentration in the rate-limiting step and that the pre-equilibrium approach relies on the reaction before the rate-limiting step is at equilibrium, requiring the equilbrium constant. Therefore, it may be le...

Rakhi Ratanjee 1D

That information should be given to you.

Rakhi Ratanjee 1D

There is no question 114. Did you mean question 41?

Rakhi Ratanjee 1D

The reason that OH- is not included is because they cancel out when you balance the redox reaction.

Rakhi Ratanjee 1D

In one of the practice problems I was doing, I noticed that although heat is conserved from the system to the surroundings: delta H (system) = - (delta H surroundings), the same idea does not apply for entropy. For example, although enthalpy is conserved, the entropy lost by a system and gained by t...

Rakhi Ratanjee 1D

Do we have to write the phase of the molecule when writing the specific rate law?

Rakhi Ratanjee 1D

Why are there two ions on the right side: NO3- and H+ ?

Rakhi Ratanjee 1D

Also, shouldn't AgBr(s) be incorporated into both half-reactions?

Rakhi Ratanjee 1D

Aren't the oxidized and reduced species always in the same solution?

Rakhi Ratanjee 1D

If asked to give the half-reactions of an electrochemical process, do we have to flip the anode, or do we give both equations in cathode form?

Rakhi Ratanjee 1D

How do you determine if a reaction is acidic or basic?

Rakhi Ratanjee 1D

In which cases would we use Cp?

Rakhi Ratanjee 1D

Is the Gibbs free energy for diatomic molecules always equal to zero? Why?

Rakhi Ratanjee 1D

This question asks to determine which compounds are stable in terms of decomposition into elements under standard conditions. The answer referenced the Gibbs free energy of formation and stated that if the Gibbs free energy is positive then the reaction is not favorable and if it is negative, then i...

Rakhi Ratanjee 1D

Question 9.75 on the homework asks to explain whether a crystal of octahedral cis-MX2Y4 would have a higher molar entropy from the trans isomer and then explain why or why not.The answer calculated the actual molar entropies for both isomers and then compared them to find out that the cis isomer had...

Rakhi Ratanjee 1D

What is the direct relationship between entropy and enthalpy. Are they directly proportional?

Rakhi Ratanjee 1D

The standard unit of temperature is Kelvin, so anytime the temperature is constant, use Kelvin. For changes in temperature, the change you get using Celsius and Kelvin are the same so you can just use Celsius. If you're not sure, just use Kelvin.

Rakhi Ratanjee 1D

A microstate is the arrangement of the molecules in a sample, or the various ways the molecules can be distributed differently over the available energy levels. "W" measures the number of microstates than a particular atom/molecules has. Essentially, the more microstates that a particular ...

Rakhi Ratanjee 1D

For 9.11, the solutions manual states that "since P is the inverse of V for ideal gases, we can write: delta S = n*R*ln(P1/P2).
How can you derive this?

Rakhi Ratanjee 1D

Why do we have to calculate the separate entropies for change in temperature and change in volume and add them up to create the total entropy? Is there any way to combine these two changes into one equation?

Rakhi Ratanjee 1D

C(gr) just means that the natural form of carbon is in solid graphite.

Rakhi Ratanjee 1D

This question asks for the change in internal energy of the system. It was calculated in Part A that the work was +3.72kJ and in Part B that the delta H was -3267.55kJ/mol. I'm a bit confused on why the work is positive in Part C. I understand that the work would be positive in Part A because it ask...

Rakhi Ratanjee 1D

In 8.67 part B, the desired reaction is C(gr)+2H2(g)+(1/2)O2(g) --> CH3OH(l)
What is C(gr)?

Rakhi Ratanjee 1D

For the reaction 1H2+(1/2)O2--> 1H2O(liquid), the final calculation of the bond enthalpies comes to 242kJ/mol. From the tables in the textbook, the answer would work out to be a +242kJ/mol, but the solutions manual states that it is negative. Why? Also, why do you have subtract 44 kJ/mol to get the ...

Rakhi Ratanjee 1D

Generally, when you have to find the energy required for a phase change, use the formula Energy (q) = (mass of sample)*(heat of fusion/vaporization of substance in J/g)

Rakhi Ratanjee 1D

Do strong acids and bases always dissociate 100%? Are there any cases in which they won't dissociate completely?

Rakhi Ratanjee 1D

Why is SiO2 polar?

Rakhi Ratanjee 1D

Why is Cl2+ more stable than Cl2? I thought that since Cl2+ is a radical, it would be less stable than Cl2.

Rakhi Ratanjee 1D

Does the equilibrium constant change when the stoichiometric constants in the equation are halved?

Rakhi Ratanjee 1D

There is a coefficient 2 because when you compare the changes in pressure for A, B, and C, you find that the ratio is: A:B:C =10:5:10 =2:1:2 Therefore, there are 2 molecules of A, 1 molecule of B, and 2 molecules of C. The balanced chemical reaction would be: 2A(g) + B(g) <--> 2C(g) To address why e...

Rakhi Ratanjee 1D

Q: Calculate the initial molarity of Ba(OH)2 and the molarities of Ba+2, OH-, and H30+ in an aqueous solution that contains 0.43 grams of Ba(OH)2 in 0.100L of solution. For this question, I understand how to find the molarity, but I'm confused on how to set up the dissociation equation. How do you k...

Rakhi Ratanjee 1D

For the molecule CH2Cl2, why is the molecule polar, when the Chlorines could be next to each other or opposite each other? Can there be cis and trans variations?

Rakhi Ratanjee 1D

When naming the hybridization of an atom, why do you put the superscript only after the p, for example, bromine is sp^3d, even though d has two electrons?

Rakhi Ratanjee 1D

What is the difference between polar bonds and polar molecules?

Rakhi Ratanjee 1D

Re: What is the difference between trigonal planar and trigonal bipyramidal? Trigonal planar has the VSEPR formula of AX3E0, meaning that the molecule has 3 bonded pairs and 0 lone pairs on the central atom, making the bond angles each 120 degrees. Ex) BH3 Trigonal bipyramidal has a VSEPR formula of...

Rakhi Ratanjee 1D

The second rule of the VSEPR Theory Staes that there is not distinction between single and multiple bonds: a multiple bond is treated as a single region of high electron concentration. Does this mean that the probability of finding an electron in that area is greater than that of having a single bon...

Rakhi Ratanjee 1D

Question 3.45 reads: Draw the lewis structure that contributes to the resonance hybrid of nitric chloride (ClN02) with N as the central atom. My 3 lewis structures were as follows: A) N with a double bond on 0 and single bond on Cl and the other O B) N with a double bond on the opposite O and a sing...

Rakhi Ratanjee 1D

How can you determine the maximum number of resonance structures that a molecular can have?

Rakhi Ratanjee 1D

Is there a lecture on Wednesday, November 23?

Rakhi Ratanjee 1D

Z subscript eff stands for the effective nuclear charge. Effective nuclear charge is related to a reduced electrostatic attraction of outer electrons because of shielding of outer electrons by the electrons that are closer to the nucleus. Effective nuclear charge is affected by how many electrons ar...

Rakhi Ratanjee 1D

Since Oxygen has a lower electron affinity than carbon, does this exception carry forth to all the elements in group 15 since the subshell would be filled the same, or it it exclusive to oxygen?

Rakhi Ratanjee 1D

In terms of behavior of the electron in the atom, what behavior does the magnetic quantum number explain vs. the spin magnetic quantum number? What does "spin up or down mean" in terms of the electron's behavior?

Rakhi Ratanjee 1D

The magnetic quantum number was defined as the number that "labels different orbitals of a subshell" from lecture on Wednesday. The allowed values are l, l-1.....-l If that number is supposed to differentiate particular orbitals, how can it be negative?

Rakhi Ratanjee 1D

Leanne, I'm a bit confused on your statement. You say that when 3d is completely filled, then it is lower in energy than 4s? How can this be the case when you're adding electrons? Don't more electrons mean greater energy?

Rakhi Ratanjee 1D

Q: What did sodium tell chlorine when they met?
A: I've got my ion you.

Rakhi Ratanjee 1D

1.21 Q: Pick the observation that best supports the idea that electromagnetic radiation has the properties of particles. Explain reasoning. A: photoelectric effect because if light were acting as a wave then the intensity would be proportional to amplitude (size) of the wave and bigger waves means g...

Rakhi Ratanjee 1D

For 29, why do you divide by the number of atoms in a mole?

Rakhi Ratanjee 1D

For this question, my reasoning was that the answer would be A) the speed of the radiation decreases as frequency of electromagnetic radiation decreases, because a higher frequency means that more waves are traveling per second or more cycles per second. The solutions manual, however, states that A)...

Rakhi Ratanjee 1D

In a combustion reaction, are the products of H2O and CO2 always in the gas form? Are there any instances in which they would be in liquid form? Also, is combustion always with gaseous 02?

Rakhi Ratanjee 1D

Generally, how many significant figures are needed when rounding percentages?

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