CHEMISTRY COMMUNITY

AlyssaBei_1F

No I believe we just turn in 7 problems this week.

AlyssaBei_1F

Do we need to know what the graphs will look like for zero, first, and second order reactions?

AlyssaBei_1F

Will the graph of a second order reaction always be a straight line with a negative slope?

AlyssaBei_1F

In the 7th edition, 7a problem #7 lays it out. The units for zero order are (mol A)/L/s. The units for first order are s^-1. The units for second order are L/(mol A)/s.

AlyssaBei_1F

Activation energy is the energy needed for the reaction to occur. It is also known as Ea. The less activation energy needed the more favorable the process/reaction is.

AlyssaBei_1F

In lecture today, many equations involved integrals and derivatives. Do we need to know how to solve with integrals and derivatives for the kinetics section?

AlyssaBei_1F

In first order reactions, will it always be a straight line like the graph in lecture from today?

AlyssaBei_1F

You add Pt(s) when there is not a solid on either the anode or cathode side. Sometimes it will tell you what kind of solid to add in the problem.

AlyssaBei_1F

If the anode or cathode does not include a solid, you add Pt(s) to whatever side does not have a solid. The aqueous solutions always go near the line (I). For example Pt(s) I Na (aq) II cathode.

AlyssaBei_1F

In Friday's lecture, the answer to his example was Cu(s) I Cu^2+(aq) II Fe^3+ (aq), Fe^2+(aq) II Pt(s). Why is the Pt(s) added?

AlyssaBei_1F

Is F in the Nernst Equation a constant?

AlyssaBei_1F

Oxidation (from reactants), oxidation (from products) II reduction (from reactants), reduction (from products).
Separate with comma for same states
Sperate with I when different states

AlyssaBei_1F

Is voltage always positive?

AlyssaBei_1F

Cu(s) and Cu2+(aq) is separated by a I because it is two different states. Fe3+(aq) and Fe2+(aq) is separated by a comma because they are the same state.

AlyssaBei_1F

In the Van't Hoff equation, is the 2 R's in the equation both Boltemann's constant?

AlyssaBei_1F

The çhange in G is not dependent on path taken so it would not be a state function.

AlyssaBei_1F

G=-RTlnK, in this equation does K represent the confrontation of products over reactants?

AlyssaBei_1F

You need a constant pressure. The Van't Hoff equation can be used to calculate K @ different temperature if delta H is known.

AlyssaBei_1F

Gases have the highest entropy value because the molecules have the greatest freedom of movement. Entropy of solid<Entropy of liquid<entropy of gas

AlyssaBei_1F

When does delta H replace q in delta u=q+w?

AlyssaBei_1F

R (constant) is in Kelvin, so it would be more efficient to use K.

AlyssaBei_1F

R (constant) is in Kelvin, so it would be more efficient to use K.

AlyssaBei_1F

micro states to the power of molecules are W in the equation s=kblnW

AlyssaBei_1F

When do you use -delta H/T versus +delta H/T?

AlyssaBei_1F

I get confused on identifying open vs closed systems. Can someone give me examples of each and how they go about differentiation one vs the other?

AlyssaBei_1F

Will the Lewis Structure be given for a problem with bond enthalpy on a test?

AlyssaBei_1F

Condensation releases heat because you are going from a gas to liquid state. In a gas molecules are moving rapidly, so in order to slow the particles you need to release heat to turn them into a liquid.

AlyssaBei_1F

I think of work like exothermic and endothermic. Doing work on a system is positive because you are adding energy. Work by a system is negative because energy is released.

AlyssaBei_1F

In lecture on Friday, Dr. Lavelle said bond enthalpies of diatomic molecules are accurate, but all others are averages of many different molecules. Can someone give me an example of what he means?

AlyssaBei_1F

Can someone explain how enthalpy is a state property?

AlyssaBei_1F

Endothermic has a positive delta G and exothermic has a negative delta g. Endothermic requires heat and exothermic releases heat. Endothermic favors product formation and exothermic favors reactant formation.

AlyssaBei_1F

Kp is usually atm or bar, but make sure you use the same units for all the gases in the problem.

AlyssaBei_1F

You can use it for both, but be careful when coming up with your final answer. Use Kp instead of Kw.

AlyssaBei_1F

For calculating the pH of a weak acid and its salt, is an extra number given, but the steps to complete the problem are the same?

AlyssaBei_1F

Is 25 degrees C the standard temperature for equilibrium?

AlyssaBei_1F

Can someone explain Le Chatelier's Principle?

AlyssaBei_1F

On Wednesday in lecture, Dr. Lavalle went over an example about ATP Hydrolysis with ATP + h20 as the reactants going to ADP + Pi. Can someone explain the ice table values, such as how he got them and the answer?

AlyssaBei_1F

Brackets are only used when dealing with concentration.

AlyssaBei_1F

If the temperature is increased, molecules increase their speed and movement. If temperature decreases, molecules decrease their speed and movement.

AlyssaBei_1F

When the heat is lowered, you are giving off heat, so it would be an exothermic reaction (shifting towards the formation of products).

AlyssaBei_1F

Can someone explain to me how to use the Le Chatelier's principle to figure out this problem?

AlyssaBei_1F

K' refers to the reverse reaction. You can find K' by calculating 1/K.

AlyssaBei_1F

Kp is only used when dealing with gases.

AlyssaBei_1F

When combining the two equations, why is Cl^2 not included in the final equation?

AlyssaBei_1F

In the 7th edition book Table 9C.1 shows the difference. The N is underlined in nitro and the O is underlined in nitrito

AlyssaBei_1F

To figure out if a compound is polydentate, do we have to draw the lewis structure and count the number of lone pairs or is there an easier way to go about doing this?

AlyssaBei_1F

To find the coordination number, do we have to draw the Lewis structure and count the number of bonds? Or is there an easier way than drawing the lewis structure?

AlyssaBei_1F

In 6C #19 7th Edition, how can we conclude that HClO2 is a stronger acid than HClO?

AlyssaBei_1F

How can you tell if an atom is polar or non-polar?

AlyssaBei_1F

For polarizability, would the trend decrease across a period from right to left because the atoms are getting smaller from right to left?

AlyssaBei_1F

Is there a trend for polarizability?

AlyssaBei_1F

How do we know [Fe(CN)6] has an overall charge of -4? Is it given?

AlyssaBei_1F

Can someone explain to me how to determine which atom has a higher polarizability?

AlyssaBei_1F

Do we need to know how to draw sigma and pi bonds?

AlyssaBei_1F

Is there an easy way to figure out if a molecule is polar?

AlyssaBei_1F

<180 or <90

AlyssaBei_1F

Can someone explain why larger lone pairs electrons force bonding electrons closer together?

AlyssaBei_1F

What is the difference between molecular geometry vs electronicgeometry?

AlyssaBei_1F

Can someone explain to me how we determine polarizing power?

AlyssaBei_1F

A resonance is a Lewis structure that have bonds in different equivalent locations.

AlyssaBei_1F

Can someone explain to me why smaller and more highly charged cations have more polarizing power?

AlyssaBei_1F

Can someone explain to me why smaller and more highly charged cations have more polarizing power?

AlyssaBei_1F

When determining bond angles, will a linear structure always have 180 degrees? Will a trigonal planar structure always have 120 degrees? Will a tetrahedral structure always have 109.5 degrees?

AlyssaBei_1F

The energy is given and my TA said there is a sheet that tells you the energy of bonds.

AlyssaBei_1F

Can someone explain to me the process for determining bond lengths?

AlyssaBei_1F

All elements must have an octet, but you look at formal charge to find the most stable Lewis structure.

AlyssaBei_1F

H, He, Li, and Be do not obtain a full octet. Elements in period 3 or below can have an expanded octet, including S, P, and Cl.

AlyssaBei_1F

Kg is the SI unit. We only use grams when working with moles. Always convert to kg.

AlyssaBei_1F

Does electronegativity have the same trend as electron affinity on the periodic table?

AlyssaBei_1F

Wavelength units are m or nm. If they give you nm, make sure to convert to m (SI unit for wavelength)

AlyssaBei_1F

The central atom is most likely the atom with the lowest ionization energy

AlyssaBei_1F

Electrons are equal to the number of protons. If an element has more protons, then it will have more electrons, causing the element to have more shells and be bigger.

AlyssaBei_1F

On Problem 2D #11 (7th edition), can someone explain to me how O2- is smaller than N3- for polarizability?

AlyssaBei_1F

On Problem 1A #15 (7th edition book), I understand all the steps to get 0.112, but I am confused on how n2^2 is 9 and then you take the square root and the answer for n2 is 3. Can someone explain this to me?

AlyssaBei_1F

On today's lecture notes, there was bond lengths labeled on certain bonds. For example, in the benzene example the double bonds had 1.34A and the single bonds had 1.54A. I am confused on how we figure out these numbers.

AlyssaBei_1F

The central atom is the atom in the middle. It is determined by the atom with the lowest ionization energy. Ionization energy increases up a group and increases across a period.

AlyssaBei_1F

The central atom is the atom with the least ionization energy. Hydrogen is never a central atom. Ionization energy increases up a group and increases across a period making Flourine (F) have the largest ionization energy.

AlyssaBei_1F

The E would represent the energy of the photon. The work function or threshold energy would be the energy required to remove an electron.

AlyssaBei_1F

kg is the SI unit. Grams is only used for moles. Also Joules is kg m^2 s^-2, so it would make sense to use kg.

AlyssaBei_1F

In the 7th Edition Book, Section 1.D #23, it asks how many orbitals can have the following quantum numbers in an atom? I understand how to get a, b, and d, but I an confused on c) n=2. Can someone explain to me how the answer is 4?

AlyssaBei_1F

In the 7th Edition Book, Section 1.A #9 it asks for us to fill out a chart. I understand the first three columns, but don't understand the last column that says "event." How do we know the event based on the answers we found and are given? Is there a chart that tells you the event based on...

AlyssaBei_1F

In the 7th edition book, section 1.E #13 asks to write the ground state electron configuration for a) silver. Is the answer [Kr]4d^105s^1 an okay answer or do we need to draw it out?

AlyssaBei_1F

Will we be given a sheet with equations for chemistry test #2?

AlyssaBei_1F

Can someone explain to me where 4pi comes from in the heisenberg indeterminacy equation?

AlyssaBei_1F

The negative sign means the bound electron has lower energy than the free electron. The energy is still positive.

AlyssaBei_1F

Constructive is when waves are in phase, meaning the waves are on the same pattern which creates a greater amplitude. Destructive is when waves are out of phase, meaning the waves are opposite of each other, which creates a smaller amplitude. This shows that waves show diffraction patterns and have ...

AlyssaBei_1F

Planck's constant is used in the equation E=hv(frequency) and various others. It is equal to 6.626x10^-34 J/s

AlyssaBei_1F

You want to multiply by the smallest possible number that will give you a whole number. I would multiply 3.5 by 2 to get 7.

AlyssaBei_1F

Wavelength is the distance from one peak to another. Frequency is the amount of waves over a given period.

AlyssaBei_1F

The theoretical yield is always bigger because due to side reactions, impurities, etc. the actual yield will be less.

AlyssaBei_1F

It does not matter if you use mL or L, but you have to stay consistent throughout the whole problem. I usually just change to liters.

AlyssaBei_1F

I am confused on this problem. To find out all the parts (a,b,c,d) do we only use the equation E=hv or do we need to use another equation also?

AlyssaBei_1F

The correct answer would be d (E=hv). E = energy h= Planck's constant v= frequency

AlyssaBei_1F

The molecular formula tells you how many atoms there are per element, so all you would need to do is count the atoms. You would not be able to do this with the empirical formula though because the empirical formula is a ratio.

AlyssaBei_1F

The only equation I can think of is c=(lamba)x(v). I don't think c=delta x v exists.

AlyssaBei_1F

For the states of atoms, I would just look it up. After doing problems with the states of atoms, it becomes easier because you see it more often.

AlyssaBei_1F

On the limiting reactant video, the example is calcium carbonate reacts with water to form calcium hydroxide and ethyne. I understand up to calculating the moles of CaC2 and H2O, but am confused why we have to multiply 1.56 (moles of CaC2) by 2. Can someone help me with this?

AlyssaBei_1F

Sadly there is no trick, the best way is to memorize.

AlyssaBei_1F

The limiting reagent is the reactant that gets used up first in a chemical reaction. It determines how much product is produced. There cannot be two limiting reagents because once one reactant is used up the reaction cannot continue.

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