CHEMISTRY COMMUNITY

Joowon Seo 3A

It relates the change in temperature to the change in reaction constant.

Joowon Seo 3A

work is positive when it is done on the system. When the system does work, the work is negative.

Joowon Seo 3A

When delta G is negative, there is energy free to do work. Cell potential wants to go down. IF cell potential goes down there is a release of energy free to do work.

Joowon Seo 3A

the anode is more negative and the cathode is more positive.

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Generally all diatomic elements being themselves in their natural state like gaseous hydrogen or graphite for carbon.

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It is when three molecules collide in order to form a product.

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It entirely depends on the reaction itself.

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If you plot ln of reactant with time and it is a straight line it is first order. If you plot 1/R vs time and it is a straight line it is second order.

Joowon Seo 3A

The equation helps us relate temperature, reaction constant, and the activation energy. IF plotting lnk to 1/T the slope is -Ea/R

Joowon Seo 3A

if we change a second order equations reactant by a factor, its rate will change by the factor^2

Joowon Seo 3A

you can look at the the factor of how much the rate and the reactant are changing then deduce which order the reactant is.

Joowon Seo 3A

It is ok to use either but remember that the those two are not the same thing.

Joowon Seo 3A

it is used to derive k as it is the negative slope of the equation.

Joowon Seo 3A

No matter how we change the concentration of the zero order reactant, the reaction rate will not change. For a first order equation, the rate will linearly change when we change the reactant. For a second order when we change the reactant, it will change by the square of the reactant change.

Joowon Seo 3A

A slow step is the series of reactions use to convert the initial reactants to the final products.

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The property does not change no matter how much of it occurs. Therefore if we must balance a reaction we can't change $E^{\circ}$

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The potential difference is the maximum amount of Gibbs Free energy, the energy available to do work.

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Because there is no more free energy to do work when the reaction is at equilibrium because the reaction is at the most stable point.

Joowon Seo 3A

We use $E=E^{\circ}-\frac{RT}{NF}ln(Q)$

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Since the left side is the anode, the thing on the left must be oxidized.

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$G^{\circ}$ is when the reaction is under standard conditions meaning that the temperature is at 25 C and the pressure is at 1 atm
Regular G is for any temperature and for any pressure

Joowon Seo 3A

When delta G is negative it becomes spontaneous and the reaction will favor the products if delta G is positive the reaction will favor the reactants

Joowon Seo 3A

K is the equilibrium constant where the equation will not change if K=Q then the standard change in gibbs free energy is zero. so we get the equation from $\Delta G=\Delta G^{\circ}-RTln(Q)$ to G=-RTlnK

Joowon Seo 3A

Spontaneity means that the change in gibbs free energy is negative. Most exothermic reactions have a decrease in enthalpy meaning an increase in heat to the surroundings as well as an increase in entropy

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We are assuming that both the initial and final entropy will go up the same amount so that the difference in the entropy will stay the same.

Joowon Seo 3A

Since it uses all of the heat going into the system and converts it to work. The heat is not converted to the temperature of a system.

Joowon Seo 3A

work of a system will always be negative because we use the pressure external to calculate the work. The system will lose energy since it is doing work

Joowon Seo 3A

We start out with the equation
$\Delta S=q/T$
we will then have the equation
$w=-nRTln(V_2/V_1)$
since for an isothermal reaction we have
$q=-w$
Then we can sub in that for entropy and we will have the equation
$\Delta S=nRln(V_2/V_1)$

Joowon Seo 3A

They are satisfied under conditions of standard pressure.

Joowon Seo 3A

Work is not a state property because it depends on the path taken. If you walk a really roundabout path and a path straight from point a to point b you will spend a different amount of energy and do a different amount of work.

Joowon Seo 3A

They do not necessarily happen by themselves since enthalpy is a state function. It depends on the intermediate energy when going from the initial enthalpy to the final enthalpy.

Joowon Seo 3A

work and heat depend on how the path was taken from the initial value to final value.

Joowon Seo 3A

force is pressure times area since pressure is the amount of force in a given area.

Joowon Seo 3A

Adiabatic means that energy cannot be absorbed or ejected as heat so the system must do work or work must be done on a system in order to absorb or release energy.

Joowon Seo 3A

Because of the energy to convert boiling water to steam is a lot. So when steam condenses on your skin, all the energy expelled to form the bonds between water will get sent to your skin causing extreme burns.

Joowon Seo 3A

There needs to be energy required to break the hydrogen bonds in between the water molecules.

Joowon Seo 3A

To accommodate for the phase change of the material, add the reaction enthalpy of the phase change onto the reaction.

Joowon Seo 3A

It would depend on the information the question gives you. It also depends on what you are looking for. If you are looking for an accurate enthalpy, you should avoid using bond enthalpies because it is the least accurate.

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Hess's law states that enthalpies can be additive. You can add the total reaction enthalpies.

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Enthalpy is a state because it does matter how it gets to the final value.

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A buffer has a weak acid/base with its conjugate. The conjugate can take/give a proton in solution, so it can resist a change in pH.

Joowon Seo 3A

A reaction is generally endothermic if involves the breaking of bonds which causes the absorption of heat. A reaction is generally exothermic when the product forms bonds.

Joowon Seo 3A

The q value will eventually reach k given a long period of time, because that's where the reaction occurs at equilibrium.

Joowon Seo 3A

A weak acid does not give up it's protons as easily as a strong acid. Therefore, there is a less concentration of hydronium ions and therefore a lower pH

Joowon Seo 3A

In an endothermic reaction, heat can be used to break bonds. Therefore, if you increase the heat (which could be noted as a reactant) by Le Chatelier's principle, the formation of products increases.

Joowon Seo 3A

If we change the volume so that the pressure increases, the concentration of the products and reactants changes, so more reactions happen to keep it at the equilibrium constant.

Joowon Seo 3A

It applies if the physical parameters are produced. For example, if a reaction produces heat, more reactions will be favored to form reactants if we add heat.

Joowon Seo 3A

Solids cannot have a concentration. Liquids are not included in the equation since their concentration essentially does not change so we leave it out.

Joowon Seo 3A

All weak acids or bases have ka or kb values. Strong acids are when the compounds totally dissociate, so they would have to have remarkably high k values in order to be called strong acids or bases.

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It is called partial pressure because in a mixture of gases, each individual gas contributes to the overall pressure.

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Weak acids generally don't give off their H+ ions as easily as strong acids. It will generally give you the pKa value of an acid since every proton of a weak acid doesn't dissociate.

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It depends on how many lone pairs the ligand has. For example, en has two nitrogen with lone pairs and is a bidentate.

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Myoglobin contains a naturally occurring coordination compound where the central TM cation is Fe. The Fe binds to oxygen in order to transport it around the body.

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It is polyprotic if it can recieve or give more than one H+

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polarizability depends on size of an atom, because the electron cloud can distort more easily. polarizing power: the smaller the cation, the more powerful it is.

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Only if the complex is negatively will the metal end with -ate. Furthermore some metals have special names. For iron for example, you would say ferrate instead of ironate.

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Because it is easier for the first hydrogen to be dissociated from the acid. The atom holds on to the second and the third protons more tightly than the first.

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So to remove electrons from 1 mol of sodium it is 150.6 KJ.mol^-1. So to find the energy needed for one sodium atom, you just need to divide the number by the number of atoms in a mol.

Joowon Seo 3A

Lavelle has stated in class that the 1st and 2nd group metals do not affect pH so they do not have to be written down in the proton transfer.

Joowon Seo 3A

The p in p[OH-] stands for -log base 10. You can look at a graph of y=p(x). When the inputted value increases, the function decreases. Likewise the value of When the concentration of OH- decreases, the function p[OH-] increases. This is true for [H+] as well. https://dr282zn36sxxg.cloudfront.net/dat...

Joowon Seo 3A

The things that affect intermolecular bonds are the types of bonds i.e. hydrogen and dipole-dipole bonds and the polarizability of the molecule where higher polarizability will mean greater bond strength.

Joowon Seo 3A

The higher the electronegativity, the shorter the bond, the harder it is to break the bond.

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Dirty coal has more sulfur in it. So when it burns it releases more SO2 than clean coal

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Polydentate shapes are like rings since they have multiple bonding sites.

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Since ligands donate an electron pair, they are considered lewis bases.

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CN binds to the Fe ion. The Fe ion is the central TM. By definition CN is a ligand. The charge is -4 because the Fe ion is +2. Since there are 6 CN- it becomes:
+2-6=-4

Joowon Seo 3A

Acids typically donate a proton. For example, with HCl aqueous it beomes H+ and Cl-.

Joowon Seo 3A

Basically it refers to how many bonding sites the ligand has, like the ligand that forms the ring structure for example.

Joowon Seo 3A

Many transition metals like to form octahedrals. The iron in the complex is bonded to 5 nitrogens and in this case the O2 binds with the iron ion in the complex.

Joowon Seo 3A

If you look at the cisplatin there are two Cl- ions on the same side. These Cl- ions fall out and cisplatin binds to the nitrogen in two diferent guanine base pairs. This essentially stops the enzyme from taking apart the DNA, so the cell cannot divide.

Joowon Seo 3A

It is because of the arrangement of electron densities. Since in a trigonal planar arrangement there are three regions of electron density therefore the angle has to be <120, but in a tetrahedral arrangement there are four regions of electron density therefore the angle has to be <109.5.

Joowon Seo 3A

I am not sure what you mean but if dipoles are on the same side (or adjacent to each other) will not mean that they will not cancel out. For example BF3 where the shape is a trigonal planar. There are two fluorides on the bottom side of the molecule and one fluoride on the top, yet it is non-polar.

Joowon Seo 3A

Since every molecule has electrons, every molecule will experience these forces. A van der waal force or induced dipole - induced dipole will be created because some discrepancy in electron density will create induced dipoles.

Joowon Seo 3A

Arrangement is the arrangement of electrons around the central atom. Shape is how those electrons repel each other and form the shape of the molecule.

Joowon Seo 3A

Bent and angular are pretty much the same thing. You must look out however that bent or angular can have different bond angles. An arrangement of a tetrahedral and a shape of bent (>109.5) is different from an arrangement of a trigonal planar and the shape of bent (>120).

Joowon Seo 3A

The shape affects it since a longer molecule has more surface area to interact with the other molecule than say a spherical molecule resulting in a stronger bond.

Joowon Seo 3A

The size of the molecule generally affects polarizability. When polarizability of molecules increase the energy of bonds between molecules increase resulting in higher melting and boiling points.

Joowon Seo 3A

AsF5 has more electrons. Therefore has more polarizability, which means a higher boiling point.

Joowon Seo 3A

Boiling point increases as a result of a higher intermolecular bond. For example water, which has hydrogen bonding, has stronger bonds than ethanol, which is nonpolar. This is shown by water's higher boiling point.

Joowon Seo 3A

It is dependent on the polarizability of the two molecules (whether it has more e-). The distance of the bonds also matters, but it is mainly dependent on polarizability.

Joowon Seo 3A

I think you need to know the trend of electronegativity where it is opposite to the size of an atom (where it increases across a period and up a group)

Joowon Seo 3A

B and Al are also exceptions to this rule, as they must get 5 e- to get to an octet. However, since that is too many electrons they usually get 3 more e-

Joowon Seo 3A

I think is because of formal charges, Cl and O are double bonded which means that for Cl to have a formal charge of zero, the leftover radical e- must bind to Cl

Joowon Seo 3A

Usually if its the only atom: e.g. CH4, then C, the unique atom, would go into the center. But in general, it is the one with the least electronegativity.

Joowon Seo 3A

Yes, because the cation is able to pull the shared electron more towards itself. This is used to explain why some salts cannot dissolve as easily in water than other salts.

Joowon Seo 3A

Their n=3 therefore they have access to the d-block (l=2) allowing them to place electrons into the d-block.

Joowon Seo 3A

You just have to know that an electron must be in each orbital before there are any paired electrons.

Joowon Seo 3A

It is harder to remove the second electron since the positive charge on the nucleus has a greater force on the electrons since there are less electrons. This is also why cations get smaller.

Joowon Seo 3A

You have to take into the account the charge of the nucleus as well. For example, Fluorine has more electrons than oxygen, but it has a smaller radius than oxygen. That is why the size becomes smaller if you go down a group. However, just adding electrons to an atom will make it bigger. A fluorine i...

Joowon Seo 3A

A good way to remember is that the farther away an electron is, the easier it is to remove. Since Na has a greater size than Mg, it is easier to remove an electron; therefore, Na has a lower ionization energy.

Joowon Seo 3A

Both are correct, but the other one is more specific since it showed each electron in each subshell. The problem in the first one is that one could misunderstand and put 2 electrons in one subshell before filling all of the other ones first.

Joowon Seo 3A

There is a way to prove that an atom's electron can spin up or spin down through the beaming of silver atoms shown in one of Lavelle's lectures. The electrons spin dictated where the atom would go. However,I think you just need to know that paired electrons have the opposite spin.

Joowon Seo 3A

It is energetically favorable for electrons to have that configuration

Joowon Seo 3A

So after the energy of light surpasses the minimum energy needed to eject an electron, would increasing the energy of light (the frequency) increase the amount of electrons ejected at that point or would the amount of electrons ejected stay the same?

Joowon Seo 3A

a) Use the DeBroglie equation for this problem since it both relates wavelength and the velocity of an electron. b)Use the photoelectric equation that relates to the frequency and energy in this case it would be E=h\nu + Kinetic energy but since there is no kinetic energy of an electron the kinetic ...

Joowon Seo 3A

Atomic numbers are usually carried out to four significant figures such as with hydrogen being 1.008 and carbon being 12.01. So I would just use four significant figures, and it should be fine.

Joowon Seo 3A

You would need the molar mass of the molecule you are trying to find. Then you would divide that molar mass by the molar mass of the empirical formula and get a number. If the number is like 2.9 or 5.1, you can round it to a whole number. If it is not a whole number, I suggest checking your work bec...

Joowon Seo 3A

I recommend putting them into groups and recognizing the patterns in the prefixes and the charges. Hypochlorite, Chlorite, Chlorate, and Perchlorate all have charges of -1. Polyatomic ions that start with hypo- and end with -ite have one oxygen atom. Polyatomic ions that just end in -ite have 2 oxyg...

Joowon Seo 3A

In the syllabus, it says that he uses problems from the homework. I suggest if you want to practice more for the test is to do those problems listed in the syllabus.

Joowon Seo 3A

A little unrelated, but if there is a reaction that requires a catalyst, and the catalyst is present in very small quantities relative to the reactants, is it called a limiting reactant because it severely slows the reaction, or do we classify it as something else? The catalyst is not a limiting re...

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