CHEMISTRY COMMUNITY

Ibrahim Malik 1H

The first step would be to balance all the phosphorus on both sides of the equation. Next, you would add an H2O to the reactant side in order to balance the oxygen. Once the oxygen and phosphorus are balanced, you add an H+ to whatever side is needed an balance the hydrogens. Since the reaction occu...

Ibrahim Malik 1H

Microscopic reversibility is always happening at equilibrium, because at equilibrium the forward and reverse rates are equal to each other. Microscopic reversibility states that at a small, molecular level, there is activity taking place between molecules but this activity cancels each other out (fo...

Ibrahim Malik 1H

A reaction would be first-order if the exponents on the elements in the rate law add up to 1. Likewise, the reaction would be second-order if the exponents on the elements in the rate law add up to 2.

Ibrahim Malik 1H

In a zero order, K has the units of concentration/time, in a first order the units are 1/time, and in a second order the units are 1/concentration*time.

Ibrahim Malik 1H

Initial reaction rates are a function of only reactant concentration, this allows us to find the order of the reactants only without getting product concentrations involved. The later rate would be that of the equilibrium and would not tell us how fast the reaction occurs.

Ibrahim Malik 1H

When solving for the reaction order, you want to try and divide the experiments as to end up with a whole number. However, ending up with fractions wouldn't necessarily make the problem wrong.

Ibrahim Malik 1H

Gibbs free energy is a state function that tells us a reactions relationship between enthalpy (positive if exothermic, negative if endothermic) and the entropy along with temperature. Gibbs free energy is defined in terms of thermodynamic properties that are state functions as well. If the change in...

Ibrahim Malik 1H

If the salt bridge was not present in a galvanic cell, there would be no ion transfer, meaning the solutions would not stay neutral. After a certain amount of electron transfer, the exchange would stop due to there being no salt bridge present to transfer ions. With no salt bridge, the galvanic cell...

Ibrahim Malik 1H

When calculating the Ecell, you know that you must always flip the value with a smaller voltage, as the Ecell must be positive since cells / batteries do work. The Cu has a smaller E value so when calculating the Ecell, the E value of Cu is "flipped".

Ibrahim Malik 1H

Delta G refers to the change in Gibbs Free Energy, while K is the equilibrium constant which refers to the direction in which product and reactant formation is favored. When K=1 , the concentration of products is equal to the concentration of reactants, meaning there is no side of the reaction that ...

Ibrahim Malik 1H

When you are thinking of negative temperatures, you are most likely referring to a negative Celsius. However, when we look at temperature we must convert to Kelvin, and there can never truly be a negative temperature when referring to the temperature in Kelvin as 0 degrees K is the lowest possible t...

Ibrahim Malik 1H

Depending on which value you use, R can have the constants: J*K^-1*mol^-1, L*atm*K^-1*mol^-1, L*bar*K^-1*mol^-1, or L*Torr*K^-1*mol^-1. You use the various values of R based on the other variables used, make sure all the units cancel out and you are left with the units you are trying to find.

Ibrahim Malik 1H

Solids and liquids have a set volume, so there can be no change in volume. Hence, the change in V or delta V is 0.

Ibrahim Malik 1H

Solids are the most compact state, molecules are tightly packed together and this in turn creates rigid structures that do not change shape or volume. Liquids have weaker bonds, allowing for a change in shape but with a set volume. Gases have the weakest bonds out of the three, gases occupy the shap...

Ibrahim Malik 1H

Unless stated otherwise, we assume that the gas we are working with is an ideal gas.

Ibrahim Malik 1H

When the change in internal energy of a system is negative, it means work is being done on the environment. When the change in internal energy of a system is positive, it means work is being done on the system from the environment.

Ibrahim Malik 1H

The heat required to raise the temperature of an object by 1 degree Celsius is considered the heat capacity . The heat required depends on the amount of substance, so heat capacity is considered an extensive property . When you divide the heat capacity by the amount of substance present (grams), you...

Ibrahim Malik 1H

A motor engine has pipes leading out of the engine, making it an open system as it takes in and releases air. A human body has a nose and mouth which take in and release air as well. These are both open systems as there is an exchange between the internal system (the engine and the human body) and t...

Ibrahim Malik 1H

Kp can actually be converted into Kc using the equation Kp=Kc(RT)^delta n, showing that Kp and Kc are not always interchangeable. You solve for the equilibrium constant using what the question gives you (whether it is Kp or Kc), unless noted otherwise.

Ibrahim Malik 1H

K refers to which way a compound goes in a reaction. The larger the K for a reactant, the more the compound heads towards the products, leading to dissociation and making a compound with a large K more unstable. The smaller the K value for a reactant, the more the reactants are favored, making the c...

Ibrahim Malik 1H

[H3O+] is not 1x [BaOH2] because the equation we set up for the dissociation of Ba(OH)2 only includes Ba and OH. We can only use mole ratios to determine the concentration of [OH] because it is part of the dissociation equation of Ba(OH)2 whereas [H30] is not part of the equation so we cannot use mo...

Ibrahim Malik 1H

105085381 wrote:Is the ICE table used purely to find missing concentrations?

The ICE table allows you to organize and solve for the change in concentration from the initial to equilibrium concentration, hence the name ICE (Initial, Change, Equilibrium).

Ibrahim Malik 1H

Q is a reaction quotient taken at any point of time for the reaction, whereas K is the reaction quotient taken specifically at equilibrium.

Ibrahim Malik 1H

If it's a strong acid, we know that this compound dissociates completely. It is helpful to use an ICE table just out of habit, because not all compounds would dissociate completely.

Ibrahim Malik 1H

K is a constant referring to the equilibrium constant whereas Q refers to the equilibrium at a certain point in time.

Ibrahim Malik 1H

Kc and Kp themselves do not have units. However, when calculating for them, it does not hurt to use units, for example when calculating for Kp, the pressure of gases are often measured in a unit called bar.

Ibrahim Malik 1H

You typed out the question for 11.40 instead of 11.39, is it possible you are looking at the wrong problem?

Ibrahim Malik 1H

"Sitting" to the left simply means the reaction is favored towards the reaction side, or the left side of the equation.

Ibrahim Malik 1H

In the case of HBrO2 and HClO2, it is the O--H bond that is getting broken, and because Cl has a higher electronegativity it is the more stable atom after the hydrogen atom leaves, making HClO2 the stronger acid.

Ibrahim Malik 1H

Yes. The pH + pOH of the same solution equals 14.

Ibrahim Malik 1H

Anything on this list is fair game, https://lavelle.chem.ucla.edu/wp-conten ... pounds.pdf. A UA said we most likely won't be tested on naming Iron but might as well know it just to be safe.

Ibrahim Malik 1H

Si-O bonds are polar, but SiO2 itself is non-polar because the dipoles cancel out.

Ibrahim Malik 1H

A coordination compound that is used as a chemotherapy drug is cisplatin. It binds to the replication site in DNA and prevents cancer cells from replicating.

Ibrahim Malik 1H

The radical usually ends up being the central atom in the lewis structure.

Ibrahim Malik 1H

Yes, the larger the atom is, the more likely it is to have stronger dispersion forces.

Ibrahim Malik 1H

Expanded octets rely on the d-orbital for bonding, so theoretically no more than 10 extra electrons can be bonded. However, usually the max amount of bonds won't pass 6 (SF6).

Ibrahim Malik 1H

You use di, tri, tetra, etc. when naming for compounds such as Fluorine if there is two or more in the compound. Bis, tris, and tetrakis would be used with compounds already containing di, tri, tetra, etc. already inside of a parenthesis. For example, if there are two ethylenediamine compounds, it w...

Ibrahim Malik 1H

We should be familiar with and be able to identify the compounds from name to formula and vice-versa.
Here's the link: https://lavelle.chem.ucla.edu/wp-conten ... pounds.pdf

Ibrahim Malik 1H

The lone pair electron is more spread out and occupies a larger volume, which causes a higher repulsion between two lone pairs. Bonding pairs are pulled in more tightly and occupy less space, which is why lone- bonding pairs have a lower repulsion strength.

Ibrahim Malik 1H

The most stable structure would be the lewis structure with the least amount of charges on it, and has as many formal charges of 0 as possible.

Ibrahim Malik 1H

You can determine the type of forces present in a molecule by looking at the structure of the molecule and the elements bonded to each other. For example, if a Hydrogen is bonded to either a Fluorine, Oxygen, or Nitrogen, hydrogen bonding is present. A dipole-dipole interaction is a type of Van Der ...

Ibrahim Malik 1H

Polar molecules must have polar bonds because of the difference in electronegativity between atoms. If the molecule is polar, it means the dipoles do not cancel.

Ibrahim Malik 1H

If a molecule is polar, it has dipole-dipole forces.

Ibrahim Malik 1H

The final exam will most likely be cumulative, covering every topic we have gone over in Chemistry 14A.

Ibrahim Malik 1H

Double bonds are almost negligible when finding bond angles, because we look at electron density in VSEPR, so double bonds and single bonds have the same value when calculating bond angles.

Ibrahim Malik 1H

With bond angles being repulsed by lone pairs, you won't know the specific amount unless you look up previous experimental values. As for being asked questions on the bond angles, you simply need to know that a lone pair would make the bond slightly less due to repulsion.

Ibrahim Malik 1H

The condition for double bonds is to be stable and rigid. A combination of a pi and sigma bond (forms a double bond) has restrictions on how the bond can rotate. If this bond rotates past its range of motion, the double bond would break.

Ibrahim Malik 1H

Resonance structure of atoms all exist at the same time, so each bond would technically be the same length as they are all the same bond in different resonance structures.

Ibrahim Malik 1H

VSEPR structures require a certain amount of memorization in order to remember the bond angle. For example, a Trigonal Pyramid has bond angles of <109 degrees. Dr. Lavelle hasn't mentioned whether we are required to memorize the angles yet or not, but I would assume so.

Ibrahim Malik 1H

A dipole-induced dipole is a force of attraction between two molecules that occurs when an attractive force is induced on a molecule by the presence of another polar molecule. For example, when a polar molecule nears another, say non-polar molecule, the partial charges of the polar molecule causes a...

Ibrahim Malik 1H

Can someone explain why C has a higher electron affinity than N in more detail plz? It’s confusing having said that N is closer to the right of the periodic table... Carbon has a higher electron affinity because a half-filled p sub-shell is more stable, giving Carbon a higher electron affinity than...

Ibrahim Malik 1H

Lewis acids are compounds that accept electrons, whereas Lewis bases are compounds that donate electrons. The covalent bond between the two is formed when the Lewis base donates an electron to the Lewis acid and a coordinate covalent bond is simply a type of covalent bond in which one reactant gives...

Ibrahim Malik 1H

S, P, Si, and Cl are common elements that can form an octet because they can utilize the d-orbital found in the 3rd energy level. Elements generally will only want to fill their octet and only go over and expand their octet if they have to, with these 4 elements being able to have an expanded octet.

Ibrahim Malik 1H

It is a natural attraction between positive and negative charges, and a natural repulsion between similar charges. For example, electrons in orbital around a hydrogen atom would have a coulombic attraction to the protons within the nucleus.

Ibrahim Malik 1H

Dr. Lavelle wants us to place the 4s sub-shell after the 3d sub-shell because the notation is more accurate in telling us that the 4s sub-shell is the valence shell and is a higher energy level. Traditional notation places the 3d sub-shell after the 4s sub-shell when listing electron configuration, ...

Ibrahim Malik 1H

Degeneracy refers to the equal energy states within a certain orbital. The p-orbital would have a degeneracy of 3 because there are 3 different energy states:2px, 2py, and 2pz.

Ibrahim Malik 1H

Shielding works to reduce the pull outer electrons feel from the nucleus. In an element like Na, the one electron in the third outer shell is "shielded" from the effective nuclear charge. This outer electron does not have the same interactive forces and experiences weaker interactive force...

Ibrahim Malik 1H

Energy itself can never be negative, but in Chemistry and Physics, we often use a negative sign in front of an energy value in order to indicate whether energy is lost or gained. A negative sign in front of an energy value simply states that energy is lost from the system.

Ibrahim Malik 1H

From what I can tell, the delta-v value would be 61. In your first example, delta-v, or change in velocity, is a total of 10 because the velocity ranges from -5 to +5. So going from -4 to +57, there would be a delta-v of 61.

Ibrahim Malik 1H

I doubt we would have to know specific numbers associated with colors, just know that 700 nm is red and 400 nm is violet.
Red has a long wavelength and low frequency, and violet has a short wavelength and high frequency.

Ibrahim Malik 1H

You would first convert ounces into kilograms.
Then, using De Broglie's equation we solve for wavelength with the equation:
λ = h / mv
h= Planck's constant
m= kgs
v= 92 mph converts to about 41 m/s

Ibrahim Malik 1H

As electrons fall from orbitals (for example, n=2 to n=2), the electrons lose energy, hence the negative sign within Bohr's Equation. The negative sign basically signifies energy being lost in the system.

Ibrahim Malik 1H

I would assume that we should have the basic formulas memorized, we will only get a periodic table to test with.

Ibrahim Malik 1H

I think the temperature measurement of Fahrenheit is so ingrained into the US standard of measurement that it would be inconvenient and awkward for the US to suddenly change their standard of measurement for temperature.

Ibrahim Malik 1H

I think it is best to convert units as you solve the problem because units cancel out as you solve the problem. Converting units at the end of the problem could lead to confusion and error.

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