CHEMISTRY COMMUNITY

Jacob Villar 2C

I believe the count starts from your first post in January 2020, and for those that took 14A with Lavelle last quarter, you should have a total of 100 posts by the end I believe.

Jacob Villar 2C

The reaction would likely require a catalyst to decrease the activation energy and allow the reaction to proceed.

Jacob Villar 2C

It's probably due by midnight on Sunday.

Jacob Villar 2C

Zero order reaction units are in M/s.

Jacob Villar 2C

H2O is usually in liquid form, and liquids and solids are not included in ICE tables.

Jacob Villar 2C

You would multiply the reactions to balance out the number of electrons between the half reactions.

Jacob Villar 2C

The Van’t Hoff equation can be used to calculate K when the reaction undergoes temperature changes.

Jacob Villar 2C

Generally, reduction occurs in the cathode and oxidation in the anode.

Jacob Villar 2C

Add platinum when there isn’t a solid electrode already present in the reaction.

Jacob Villar 2C

It will dilute the solution, resulting in a change in a Q value due to changes in concentration.

Jacob Villar 2C

The salt bridge allows the flow of electrons to continue from the anode to the cathode, while also avoiding disrupting the electrical charges.

Jacob Villar 2C

Can someone please explain the differences between the anode and cathode?

Jacob Villar 2C

It means that a given variable or value is present in a reaction that has occurred at standard conditions, say 298 K or 1 atm.

Jacob Villar 2C

H2O should be added first, since in doing so you would contribute to balancing the hydrogens and oxygens first. Then, add H+ to balance out the rest of the hydrogens in the acidic solution.

Jacob Villar 2C

The reducing agent is oxidized because it gives its electron to another substance, thereby reducing said substance. Thus, through vice versa, the oxidizing agent is reduced by gaining an electron from another substance.

Jacob Villar 2C

Electrochemistry, and the end of thermodynamics that deals more with Gibbs free energy.

Jacob Villar 2C

Since an endothermic reaction needs heat to proceed, the heat added to the system could be thought of as a reactant in itself.

Jacob Villar 2C

If a system is losing energy to the surroundings, then work is negative, and if it is gaining energy from the surroundings, then work is positive.

Jacob Villar 2C

The numbers you listed are values for the gas constant R, not n, which would be moles.

Jacob Villar 2C

Gaining electrons means reduction, so whichever atom has a lower charge is reduced.

Jacob Villar 2C

Yes, if delta G is negative and cell potential is positive, it means the reaction is spontaneous.

Jacob Villar 2C

Both delta H and delta S are constants.

Jacob Villar 2C

Delta G naught is delta G but under standard conditions.

Jacob Villar 2C

Since the Van’t Hoff equation would be used presumably under standard conditions, delta S is constant.

Jacob Villar 2C

Due to conservation of energy, the heat lost by the water must be equal to the heat gained by the ice

Jacob Villar 2C

Delta S won’t change under standard conditions.

Jacob Villar 2C

Adding on, I believe 3/2 is used in the instance of monoatomic gases, and 5/2 for diatomic gases.

Jacob Villar 2C

Delta G (change in Gibbs free energy) would be negative if a spontaneous reaction were to occur.

Jacob Villar 2C

It depends on the conditions of the system, for example, a system with constant volume would have Cv (notice the subscript v) and a system with a constant pressure would be written as Cp for the molar heat constant.

Jacob Villar 2C

Intensive properties do not depend on the amount of substances in the system, whereas extensive properties would be affected by the mass. Entropy is actually an extensive property.

Jacob Villar 2C

When K is less than 10^-3, and you'll notice it is able to be approximated if x/initial concentration is less than 5%

Jacob Villar 2C

q + w = delta U

Jacob Villar 2C

Q relates to heat transfer, whereas delta H refers to change in enthalpy.

Jacob Villar 2C

Constant external pressure.

Jacob Villar 2C

Heat, mass flow, and work.

Jacob Villar 2C

When pressure is constant in a system.

Jacob Villar 2C

You can use it to find entropy.

Jacob Villar 2C

ICE table are used in a problem when you're trying to find the equilibrium concentration.

Jacob Villar 2C

It is x, the equilibrium concentration, divided by the initial concentration.

Jacob Villar 2C

Bond enthalpies, since it is taken from the average of multiple molecules.

Jacob Villar 2C

In chemical reactions, these are substances marked with (s) or (l), which are not included in the equilibrium constant formula, or ICE tables.

Jacob Villar 2C

Not necessarily, as the equation for Gibbs free energy depends on the values for enthalpy, entropy, and temperature.

Jacob Villar 2C

The reaction will shift towards the reactants.

Jacob Villar 2C

It would help to keep track of what value you are calculating for and to be safe from mixing up equations.

Jacob Villar 2C

It’s a rule that an equilibrium system will shift in reaction to change in order to reach the highest point of stability possible

Jacob Villar 2C

Lavelle sees it has a useful way of visualizing the reactions.

Jacob Villar 2C

Acids donate protons and bases accept protons.

Jacob Villar 2C

How would you determine if a reaction side is endothermic?

Jacob Villar 2C

Reaction will shift to the left.

Jacob Villar 2C

It’s equilibrium concentration divided by initial concentration.

Jacob Villar 2C

You can use this equation to calculate for concentration, given that concentration is calculated by dividing moles by volume (n/v).

Jacob Villar 2C

P - Pressure
V - Volume
n - number of moles
R - ideal gas constant
T - temperature

Jacob Villar 2C

If there is more products than reactants, Q will be greater than K, and the reverse reaction will be favored.

Jacob Villar 2C

Le Chatlier's principle states that an equilibrium system will shift in order to minimize the impact of changes on the system, such as removing products, which will result in a more forward reaction.

Jacob Villar 2C

PV = nRT

Jacob Villar 2C

VSEPR is a model that shows atomic structure, but with the inclusion of factors such as bond angles and electron repulsion.

Jacob Villar 2C

A bronsted acid donates protons, whereas a bronsted base accepts protons.

Jacob Villar 2C

Stronger acids/bases are completely ionized (dissociated) in solution or water respectively.

Jacob Villar 2C

Sigma bonds are stronger due to the orbital overlap.

Jacob Villar 2C

Long bonds attribute to stronger acids, since they are weaker bonds, and therefore, the acids can be dissociated to a greater degree.

Jacob Villar 2C

Yeah the resonance structures should amount to the same overall charge.

Jacob Villar 2C

I think writing simply X or E would be sufficient.

Jacob Villar 2C

It depends on bonding pairs vs lone pairs in an atom, as seesaw has 4 bonding pairs, but 1 lone pair, whereas t-shape only has 3 bonding pairs, but 2 lone pairs.

Jacob Villar 2C

Yes, since hydrogen bonds form with the elements N, O, and F, and these are more electronegative atoms.

Jacob Villar 2C

They arrange themselves to experience as small amount of repulsion as possible.

Jacob Villar 2C

Generally the arrow points towards the more electronegative atom.

Jacob Villar 2C

Since CCl4 is a symmetrical tetrahedral shape, the dipole moments do cancel out.

Jacob Villar 2C

A dipole moment can be considered cancellable if the dipole moments move in opposite directions, and their magnitude is the same.

Jacob Villar 2C

The lone pairs located on a central atom will repel the electrons located within covalent bonds, thus decreasing the bond angles.

Jacob Villar 2C

Yes, and they can play a role in the shape of a molecule in changing the angles between atoms.

Jacob Villar 2C

Since there is a greater amount of electrons involved in bonding, the atoms are able to pull closer together, creating a shorter bond length.

Jacob Villar 2C

The total formal charge should be equal between resonance structures, although the charges of the individual atoms may differ.

Jacob Villar 2C

Energy is absorbed to be able to break bonds.

Jacob Villar 2C

Unless specifically stated to write out the full electron configuration, I believe writing the configuration with the noble gas abbreviation would suffice.

Jacob Villar 2C

The London dispersion forces within I2 are much stronger due to its larger atomic radius.

Jacob Villar 2C

I just want to clarify based on the lecture from Friday, but London forces occur in all molecules/atoms right?

Jacob Villar 2C

The extra electrons in the double bonds attract the atoms closer together, thereby reducing the length of the double bonds, yet also increasing its strength.

Jacob Villar 2C

At a formal charge of zero, the atom would be the most stable, so yes.

Jacob Villar 2C

In chemistry, it is pointed towards the negative dipole.

Jacob Villar 2C

Can someone explain to me what exactly covalent character is, what factors affect how great it is, and what the result of a high or low covalent character is?

Jacob Villar 2C

Shorter bonds are generally stronger, and longer bonds tend to be weaker.

Jacob Villar 2C

I believe that if you put these coefficients (from left to right) it should be balanced: 6, 10, 5, 3, 6, 9.

Jacob Villar 2C

Most often double bonds are drawn in order to keep in line with the octet rule.

Jacob Villar 2C

Lone pairs are the dots on a lewis structure that do not form bonds, for example, on an atom, they would be the two dots on the side.

Jacob Villar 2C

H, He, Li, and B are exceptions to the octet rule because their amount of electrons are only enough to reach the 1s orbital, and therefore, the octet rule cannot be applied in these circumstances.

Jacob Villar 2C

I believe that due to the greater amount of attraction between electrons in double bonds and triple bonds, this causes the bond length to be shorter than that of a single bond.

Jacob Villar 2C

Sometimes, the octet rule will not be satisfied with simply using single bonds, and therefore double bonds would be necessary to satisfy this rule.

Jacob Villar 2C

The atom with the lowest ionization energy is the central atom.

Jacob Villar 2C

kJ/mol, kilojoules per mole

Jacob Villar 2C

We will learn more about this later, but valence electrons (electrons sitting on the outermost orbital), are important to the bonding between atoms.

Jacob Villar 2C

You would have to find the molar mass using the empirical formula, and divide the given molar mass by this value. Then with the answer, which is usually a whole number, multiply all the subscripts of the empirical formula by the molar mass ratio.

Jacob Villar 2C

Since mega- translates to 10^6, 1 Hz would translate to 1*10^6 mHz

Jacob Villar 2C

The magnetic quantum number labels the different orbitals of a subs [censored].

Jacob Villar 2C

1 Hz is counted as 1 cycle per second

Jacob Villar 2C

Should we bet using sig figs based on given number values (ex: if the problem gives us 250 mL, we use 3 sig figs) or should we be basing the amount of sig figs we use on calculations as we go?

Jacob Villar 2C

I like to let out a big breath before taking the test to help clear my system of anxiety, and often times I'll chew gum because it helps me focus on the material rather than other small things going around in the room, which also saves time for more work on problems.

Jacob Villar 2C

The Hill system shows that the order of listing elements starts with carbon atoms, then hydrogen atoms, and then all other atoms in alphabetical order.

Jacob Villar 2C

I think that it is proper to use the same amount of sig figs throughout the entire problem, so that there is consistency with each preceding calculation. Especially with given units, the sig figs in your final answer should likely match the amount of sig figs with these given numbers.

Jacob Villar 2C

So I know that the equivalent of an Angstrom unit is 1A = 10^-10 m, but how would you convert to other significant units such as centimeters or picometers? DO you multiply by tens when converting to smaller units, or do you multiply by tens when converting to larger units

Jacob Villar 2C

According to the Law of Conservation of Mass, matter cannot be created nor destroyed, and therefore, when balancing a reaction, you must have the same amount of moles on both the reactants and products side in accordance with the conservation of mass.

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