CHEMISTRY COMMUNITY

Jacqueline Duong 1H

A porous disk is indicated by a single line, and a salt bridge is 2 lines

Jacqueline Duong 1H

n is the number of molecules, so n would equal 1

Jacqueline Duong 1H

Adiabatic is when q=0, so that would mean that there is no transfer of heat.

Jacqueline Duong 1H

When calculating Q, the concentrations do not have to be in standard conditions.

Jacqueline Duong 1H

An endergonic reaction is where energy is absorbed, therefore making delta G positive. Exergonic is when energy is released, therefore delta G would be negative.

Jacqueline Duong 1H

You would use Van't Hoff equation when there is a temperature change and K

Jacqueline Duong 1H

I am not sure, but I think it's better to know just in case. Isothermal is where the temperature stays constant in a system. Isobaric is where the pressure is constant, and adiabatic is where transfers of matter and energy as heat are prohibited.

Jacqueline Duong 1H

S is equal to zero when there is no change in the state of entropy and temperature reaches 0 K

Jacqueline Duong 1H

A reaction is exergonic when it is releasing energy, which would result in a negative delta G since it is losing energy.

Jacqueline Duong 1H

Every reaction has activation energy since it is the minimum amount of energy needed to be able to undergo the reaction. Activation energy is the difference in the energy between the transition state and the reactants.

Jacqueline Duong 1H

Delta G is equal to the maximum amount of energy available to do work at constant temperature and pressure.

Jacqueline Duong 1H

You would use that equation when there is a change in pressure.

Jacqueline Duong 1H

When work is being done ON the system, work is positive. When work is being done BY the system, work is negative since it is losing energy.

Jacqueline Duong 1H

Adiabatic is an isolated system where transfers of matter and energy as heat are prohibited. Isothermal is a process where it is the temperature that stays constant.

Jacqueline Duong 1H

Heat is the transfer of energy due to a difference in temperature. Enthalpy is the heat absorbed or released from a system under constant pressure, where it is affected by factors such as the state of the reactants and products. Temperature is a measure of heat, where temperature can be used to indi...

Jacqueline Duong 1H

Activation energy is the minimum amount of energy required for a certain reaction to occur. In an energy profile diagram, it would be the peak of the graph.

Jacqueline Duong 1H

Yep, usually A=1 unless it was explicitly stated otherwise

Jacqueline Duong 1H

A catalyst would lower the peak on a curve since it can speed up the rate of a chemical reaction by providing a faster route.

Jacqueline Duong 1H

the system will favor the forward reaction and produce more products

Jacqueline Duong 1H

Pure liquids and solids do not appear in the expression

Jacqueline Duong 1H

We can ignore x when the 5% rule applies to it, which is when x is less than 5% of the initial concentration.

Jacqueline Duong 1H

There are no units since the units should cancel

Jacqueline Duong 1H

For an exothermic reaction, the formation of products is found to be favored by lowering the temperature. For an endothermic reaction, the products are favored by an increase in temperature. So basically, raising the temperature of a reaction mixture at equilibrium will shift the reaction in the end...

Jacqueline Duong 1H

Isochoric is where the volume stays constant, isobaric is where the pressure stays constant, and adiabatic is where transfers of matter and of energy as heat are prohibited (therefore q=0)

Jacqueline Duong 1H

What is the difference between K and Kc, and when do we know to use which one?

Jacqueline Duong 1H

it's because there shouldn't be any units for K

Jacqueline Duong 1H

Yeah, it depends on the question and what units you would need to be able to cancel out

Jacqueline Duong 1H

E is the equilibrium concentration

Jacqueline Duong 1H

When using the quadratic equation to calculate the equilibrium composition, how do we know which of the two values is the right one for x?

Jacqueline Duong 1H

to add on to the x being small, if it is less than 5% of the initial value, then x is negligible when adding or subtracting from a number

Jacqueline Duong 1H

There can only be one sigma bond since a single bond has 1 sigma bond.

Jacqueline Duong 1H

A double bond has 1 sigma bond and 1 pi bond.

Jacqueline Duong 1H

A triple bond means that there are 2 pi bonds and 1 sigma bond.

Jacqueline Duong 1H

To count the number of sigma and pi bonds there are, a single bond would be sigma, a double bound would be a pi bond and sigma bond and a triple bond would be one sigma bond and 2 pi bonds.

Jacqueline Duong 1H

It would be trigonal pyramidal.

Jacqueline Duong 1H

To have a polar bond, it means that the electrons forming that bond are unequally distributed.

Jacqueline Duong 1H

Thank you, that was actually really helpful!

Jacqueline Duong 1H

Yeah, the bond angle for a t-shape would be 90.

Jacqueline Duong 1H

Not necessarily, the lone pairs just means that there's more of a repulsion and the shape changes.

Jacqueline Duong 1H

The angles for a seesaw shape are less than 90 and 120.

Jacqueline Duong 1H

Can someone please explain sigma and pi bonds and how they are formed?

Jacqueline Duong 1H

Can someone please explain cis-dichloroethene and trans-dichloroethene and what the difference between the two is?

Jacqueline Duong 1H

How can a polyatomic molecule be nonpolar if its bonds are polar?

Jacqueline Duong 1H

Why do lone pairs have a more strongly repelling effect then electrons in bonds?

Jacqueline Duong 1H

The VSEPR formula is AXnEm, where A represents a central atom, X represents an attached atom, and E represents a lone pair.

Jacqueline Duong 1H

When naming the molecular shape, do we also consider any lone pairs that are present? Or do we only take into consideration the positions of the atoms?

Jacqueline Duong 1H

Yeah, I think we would have to draw all the resonance structures with a double headed arrow connecting them.

Jacqueline Duong 1H

Ionization energy increases across a period and decreases down a group, while electron affinity is also the same where it increase across a period and decreases down a group.

Jacqueline Duong 1H

Yeah I think you would need to draw the resonance hybrid, where you draw the two resonance structures connected with a double headed arrow.

Jacqueline Duong 1H

Hydrogen bonds are weaker because it involves the attraction between hydrogen and another molecule, whereas covalent and ionic bonds are a sharing or transfer of electrons which is stronger.

Jacqueline Duong 1H

To add on, basically covalent bonds are stronger than ionic bonds in aqueous solutions, whereas ionic bonds are stronger in non-aqueous solutions.

Jacqueline Duong 1H

Nonmetals form anions because they gain electrons due to their high charge, which results in the formation of negatively charged ions.

Jacqueline Duong 1H

I think he said it was 10^-18

Jacqueline Duong 1H

What are the different shapes of each orbital and an easy way to memorize the difference? Will we need to draw them on the test?

Jacqueline Duong 1H

If I remember correctly, Schrodinger's equation is a wave equation that precisely predicts the probability of behavior of a system.

Jacqueline Duong 1H

Yeah, before the test we're given an equation sheet that has those numbers. So luckily, we don't need to memorize them!

Jacqueline Duong 1H

This is because joule is a unit of work, and the equation for work is: work = force x displacement. When you expand this, you get work = mass x acceleration x displacement. The units for mass is kg, for acceleration is m/s^2, and for displacement is m. As a result, when you times them all together, ...

Jacqueline Duong 1H

The De Broglie equation is λ = h/mv, where λ is the wavelength, h is Planck's constant (6.626 x 10^-34), m is the mass of the particle, and v is the velocity of the particle. You use this equation to find the wavelength of a moving particle.

Jacqueline Duong 1H

When you are multiplying or dividing, the number of sig figs in your answer is determined by the number with the least amount of sig figs. However, when you are adding or subtracting, the number of decimal places in the answer is determined by the smallest number of decimal places in the problem.

Jacqueline Duong 1H

Yeah, Lavelle said that he would give us the formula, and it won't be until later on when we learn how to write formulas that he will expect us to do it by ourselves.

Jacqueline Duong 1H

If I remember correctly, Lavelle said it was just easier to answer the problem since it makes it simpler and the numbers are easier to work with.

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