CHEMISTRY COMMUNITY

Giselle Littleton 1F

What is an ion-selective electrode?

Giselle Littleton 1F

What is the function of a pH meter and how does it work?

Giselle Littleton 1F

How does work relate to Gibbs Free Energy?

Giselle Littleton 1F

How is the voltage of a galvanic cell affected by anode/cathode concentration?

Giselle Littleton 1F

What is a glass electrode?

Giselle Littleton 1F

How do you find the reverse reaction rate of a reaction?

Giselle Littleton 1F

How do you get the overall order of a reaction?

Giselle Littleton 1F

Why aren't fast reactions included in rate laws?

Giselle Littleton 1F

How does the instantaneous rate react as the reaction proceeds?

Giselle Littleton 1F

How do catalysts lower the activation energy of the transition state?

Giselle Littleton 1F

How is temperature related to the activation energy?

Giselle Littleton 1F

How is molecularity related to the order of a reaction rate law?

Giselle Littleton 1F

What is molecularity?

Giselle Littleton 1F

How does a chemical reaction proceed when the Ecell=0 and K=0? Is it spontaneous or not?

Giselle Littleton 1F

How do multiple reducible species react within an electrolytic system?

Giselle Littleton 1F

How and why does galvanizing a metal help to prevent the corrosion of metals?

Giselle Littleton 1F

Does the chemical reaction being spontaneous increase or decrease cell potential?

Giselle Littleton 1F

How does electromotive force relate to cell potential?

Giselle Littleton 1F

For a basic solution, why do we balance H by adding H20 to one side and OH- to the other?

Giselle Littleton 1F

How can you know the charge of a compound in a redox reaction?

Giselle Littleton 1F

Thermodynamically stable means that the reaction is spontaneous. Thus, when △G is negative, it is thermodynamically stable.

Giselle Littleton 1F

Strong acids also have large Ka values and small pKa values.

Giselle Littleton 1F

How can you tell whether a system does expansion work by just looking at the gas moles on both sides of the equation?

Giselle Littleton 1F

Why do we subtract the bond enthalpy of the products from the reactants?

Giselle Littleton 1F

The change in entropy of the surroundings is the same as the change in entropy of the system.

Giselle Littleton 1F

I visualized this in terms of an ice cube in a warm cup of water. Two things are happening in this process. The ice cube is melting, so q for the ice cube would be positive beccause it is absorbing energy. The warm water is getting colder, so q would be negative, because it is releasing energy. △Sto...

Giselle Littleton 1F

From the homework, I've noticed that these types of question tend to ask you to find q, △H ,or, △U. I find it helpful to keep in mind that for constant volume, △U=q and for constant pressure, △H=q.

Giselle Littleton 1F

I notice that in some problems from the homework, specific bonds within molecules aren't included when calculating the bond enthalpies. Why is that and how can I watch out for those that I should not include?

Giselle Littleton 1F

Why aren't elements included when calculating the standard enthalpy of formation?

Giselle Littleton 1F

Why is a compound considered to be thermodynamically stable when △G°is negative and thermodynamically unstable when △G°is positive?

Giselle Littleton 1F

Lower pressure leads to an increase in positional disorder of the atoms as a gas is compressed.

Giselle Littleton 1F

Please explain the Second Law of Thermodynamics in relation to biological and organic reactions.

Giselle Littleton 1F

Why aren't work and heat state functions?

Giselle Littleton 1F

Does an adiabatic affect how much energy a reaction gives off?

Giselle Littleton 1F

What is the relationship between state property and enthalpy?

Giselle Littleton 1F

What is irreversible expansion?

Giselle Littleton 1F

What is reversible expansion?

Giselle Littleton 1F

Steam causes severe burns because the enthalpy of vaporization is really large for water, and thus steam carries a lot of heat from the 100 degree Celsius point.

Giselle Littleton 1F

Why is the second ionization ignored if Ka2<Ka1?

Giselle Littleton 1F

K refers to the ratio of products to a reactants in a chemical equilibrium equation when using only partial pressures. However, if you have an equation with an aqueous solution, Kc would be used because you would be determining the ratio of products to reactants in molar concentrations. I would reco...

Giselle Littleton 1F

Adding an inert gas does not have any effect because the volume doesn't change. To shift a reaction the volume must be decreased, and consequently, the pressure will increase.

Giselle Littleton 1F

If a K is less than 10^-3, it just means that the reactants are strongly favored and if K is greater than 10^3 it means that the products are strongly favored.

Giselle Littleton 1F

Additionlly, a strong acid wil have a small pKa value and a strong base will have a small pKb value.

Giselle Littleton 1F

Is there some point that the Ka and Kb values reach for an acid or base to be considered weak?

Giselle Littleton 1F

And if K<1, the reaction favors reactants, with 10^-3 being the point at which the reaction strongly favors reactants. K>1 means that the reaction favors products with 10^3 being the point at which the reaction strongly favors products.

Giselle Littleton 1F

For Q<K, why is [R]>[P] and for Q>K, why is [P]>[R]?

Giselle Littleton 1F

You can find the equilibrium constant for reactants and products if they are gas and/or aqueous.

Giselle Littleton 1F

I think of it in terms of the reaction needing to accommodate the decrease in reactant concentration in relation to the concentration of the products, so it needs more reactants so that the equilibrium constant is retained.

Giselle Littleton 1F

The reaction quotient Q describes the ratio of products to reactants when the reaction in a non-equilibrium state. K describes the same thing only when the reaction is at equilibrium.

Giselle Littleton 1F

When determining the direction of an equilibrium reaction, how do you know whether to use 10^3/10^-3 or 1 as a comparison to K? I've seen both 1 and 10^3/10^-3 being used.

Giselle Littleton 1F

When determining the direction of an equilibrium reaction, how do you know whether to use 10^3/10^-3 or 1 as a comparison to K? I've seen both 1 and 10^3/10^-3 being used.

Giselle Littleton 1F

Lewis and Bronsted acids and bases are interchangeable. A Lewis acid accepts an electron pair and a Bronsted acid donates a proton. Both types are acids whose overall charges decrease. A Lewis base donates an electron pair and a Bronsted base accepts a proton. So, the charges of both types increase.

Giselle Littleton 1F

The H+ ion in the compound can be donated to a base.

Giselle Littleton 1F

Inorganic compounds are more likely to completely deprotonate.

Giselle Littleton 1F

Also, when you're naming the complex, it might be helpful to find the determine the overall charge first.

Giselle Littleton 1F

How can you tell if a compound is a chelate by just looking at its formula?

Giselle Littleton 1F

The more bonds a molecule has, the harder it is to break apart. So the boiling point of a molecule would increase if there were more bonds because it takes more energy to break the molecule apart.

Giselle Littleton 1F

Some of the elements in the d block have unfilled orbitals. So it depends on the orbital.

Giselle Littleton 1F

The addition of a lone pair creates repulsion between the electrons, thus changing the bond angles in a way in which minimal energy is used.

Giselle Littleton 1F

The bond lengths are all the same in the resonance structure because the structures all approximate the actual structure that is supposed to form. That is, the resonance structures are a mix of structures close to the actual structure.

Giselle Littleton 1F

To form an octet, oxygen needs 2 electrons while nitrogen needs 3. But unless the atom(s) they're bonded to is specified, the more bonds the harder it is to break the molecule.

Giselle Littleton 1F

Can anyone explain what effective nuclear charge means and how it contributes to a decrease in atomic radius across a period?

Giselle Littleton 1F

As you go up and to the right, electron affinity increases as the atoms get more electronegative and are thus more likely to attract electrons. For example, oxygen is more electronegative and more likely to attract electrons than hydrogen. Oxygen is farther to the right in the periodic table and hog...

Giselle Littleton 1F

The electron's path just gets further from the nucleus.

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The probability of electron density is the likelihood that an electron is in a certain location or orbital.

Giselle Littleton 1F

What's common between them is that the electrons move closer to the nucleus in every case. So, they always move to lower energy levels.

Giselle Littleton 1F

"2" describes the shell, "p" describes the subshell, while the subscripts (x,y,z) tell you what axis.

Giselle Littleton 1F

Light also has particle-like properties as a stream of electromagnetic energy consisting of photons. Light can be absorbed or emitted in quantized or discrete values.

Giselle Littleton 1F

Amplitude contributes to the intensity of a wave. Thus amplitude has no contribution to the photoelectric effect because of its relation to intensity. Frequency is most important to the photoelectric effect.

Giselle Littleton 1F

The energy levels are infinite. What separates the elements is that specific amounts of energy are required for different atoms to absorb or emit photons.

Giselle Littleton 1F

The Bohr frequency condition demonstrates an electron's transition between energy levels. Differences in energy levels are given off as photons and only photons of certain energy are given off exactly matching the energy level difference.

Giselle Littleton 1F

The Rydberg equation is used to find the wavelength of light as it is absorbed or emitted, and electrons move between energy levels.

Giselle Littleton 1F

It's your final answer to a problem that counts for sig figs. However, to ensure that your final answer is accurate, I would keep the molar mass and other calculations in between in their longest form as evident on the periodic table and then use sig figs for your final answer.

Giselle Littleton 1F

Combustion means burning a substance in the presence of oxygen. This is a chemical reaction that produces CO2 and H20.

Giselle Littleton 1F

Hertz is essentially the number of cycles or wavelengths per second. Wave frequency is expressed through these units. We can find frequency by dividing the velocity by the wavelength.

Giselle Littleton 1F

A percentage yield means how much you get in reality compared to what you thought you were going to get. In a perfect world and lab setting, the actual yield would be equal to the theoretical yield. However, due to somewhat unavoidable factors, the actual yield will always be less than the theoretic...

Giselle Littleton 1F

Also interested!

Giselle Littleton 1F

The beginning of a problem states that a solution is diluted with 1.00 L of 0.4M potassium chloride. Does 0.4M stand for 0.4 mols or O.4 mols/L (molarity)?

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