CHEMISTRY COMMUNITY

Ana Pedreros

A triprotic acid is an acid that has three acidic protons. phosphoric acid is an example of triprotic acid.

Ana Pedreros

In problems like 15.61 and 15.63, K values are given at different temperature but they are not specified to be k' or k. How does one decide which is which?

Ana Pedreros

in this question part b calls for the time required for the concentration of B to increase to 0.19 M, given that k=.0035 1/Mmin in the rate law for the loss .The solution manual has the answer .055(molA)/L= .37[A]0. Can someone explain how they got .37

Ana Pedreros

Zero-order reactions usually imply a catalysts since the rate is only defined by k, not on how much the concentration of the reactants are increased.

Ana Pedreros

Free expansion can be seen when trying open a tight jar. If you run the jar under hot water, the increase of heat will cause the gas inside to expand and push pressure onto the lid slightly. This will cause the lid to loosen and open easily.

Ana Pedreros

The rate constant increases for an increase in temperature

Ana Pedreros

If the unit for first order reaction is 1/s, then why does the first order reaction of question 15.11 have the units mols/Ls?

Ana Pedreros

The rate law tells us the rate at which the reaction occurs, and the equilibrium toward which it proceeds. It is derived from the concentrations or partial pressures of the reactants.

Ana Pedreros

Since H2 is a gas the pressure is listen instead of its concentration, similar to partial pressure expression.

Ana Pedreros

When the cell potential is positive the reaction is favorable to occur and therefore spontaneous. This can be related to the equation of Delta G = -nfe n cannot be negative and F is positive therefore a positive cell potential will result in a -delta G making the reaction spontaneous.

Ana Pedreros

Yes this is an intensive property because it has a set voltage regardless of the electrons passing through it.

Ana Pedreros

The electromotive force or emf is the energy provided by a cell or a battery per coulomb of charge passing through it, and it is measured in volts. The cell potential is the measurement of how much voltage exists between two half cells of a battery. While the emf is the potential difference between ...

Ana Pedreros

When given the number of moles and asked to find delta G, you can use the moles when finding entropy by subtracting the number of moles of reactants from the products.

Ana Pedreros

I think there was two questions that required an ice table for the midterm. Only the question that specified no approximations could be made required the use of the quadratic formula. The other one however could be approximated.

Ana Pedreros

Thank you so much!!

Ana Pedreros

Is there homework due this week in discussion?

Ana Pedreros

This is used in monoatomic ideal gases. At constant volume the heat capacity, Cv = 3/2R, and at Constant Pressure, Cp= 5/2 R

Ana Pedreros

This equation is used when you are looking for the change in entropy of a molecule based on its degeneracy (W or the number of ways the atom can be arranged) at any temp. Kb is the boltzmann constant = 1.381 x 10^-23 J/K.

Ana Pedreros

Delta H equals q when there is no work done (this could happen when the volume does not change). this means that the enthalpy change equals the heat that is exchanged between the system and its surroundings

Ana Pedreros

Delta H is the heat of reaction under constant pressure and Delta U is the heat under constant volume . Delta H is equal to Delta U, the change in internal energy (heat transfer), plus P, constant pressure, times the Delta V, the change in volume. They are only equal when Delta U is under typical co...

Ana Pedreros

Yes, when a system is at equilibrium, the internal pressure is approximately equal to the external pressure.

Ana Pedreros

This is correct because If work is done by a system, the system is using energy, therefore losing its internal energy causing a negative w. If work is done ON a system, energy is being put into the system making w positive.

Ana Pedreros

Enthalpy is the amount of heat, $\Delta$ H, released or absorbed at a constant pressure, q.

Ana Pedreros

if looking for Kp with concentration given, n/v, can be substituted for the concentration and the pressure can be isolated in order to find the partial pressure of that gas and compete the Kp expression.if looking for Kc with pressure given, p, can be inserted in the equation and n/v can be isolated...

Ana Pedreros

The quadratic equation leads me to two x's, one Is .14, and the other is .44. in the solution manual it says .44 is negative but I've repeated my calculations numerous times and cannot achieve a negative .44. How do I know which x to use to find the PH?

Ana Pedreros

Temperature and pressure are directly proportional when the volume is constant, and Temperature and volume are directly proportional when pressure is constant.

Ana Pedreros

8*10^-4 has one sig fig because you only count the sig figs in the number being multiplied. I believe Lavelle has stated that 2 decimal places for the answer is acceptable for these problems.

Ana Pedreros

if given the components of a reaction and a Kb/Ka, does a larger Ka mean the reaction entails the dissociation of an acid?

Ana Pedreros

If temperature changes the equilibrium constant, then can Q be compared to K?

Ana Pedreros

If asked for the K expression, can Kc and Kp be used interchangeably?

Ana Pedreros

Are ice tables always based on concentrations?

Ana Pedreros

yes and you could also use ke=1/2mv^2

Ana Pedreros

most likely the answer will be just sp3

Ana Pedreros

If its a coordination compound it has to have -o -ido or -ato at the end of the name

Ana Pedreros

This depends on the electronegativity of the atoms creating the bond

Ana Pedreros

The recognized strong bases and acids are not a lot. They're easily recognizable. Some strong bases are KOH, NaOH,Ba(OH)2,CsOH, Sr(OH)2,Ca(OH)2,LiOH, RbOH. Some Strong Acids are HI, HClO4, HCl, H2SO4, HNO3, HClO3.

Ana Pedreros

a tetrahedral has 4 regions of electron density, while a square planar has six. A square planar is made up a 2D tetrahedral with a pair of lone pairs are at each end.

Ana Pedreros

Bases feel soapy because they dissolve the fatty acids and oils on your skin. When a base is mixed with the fatty acids, soap is produces. This is significant because its a characteristic of a base.

Ana Pedreros

The s character basically means the percentage of sigma bond in a hybridization. In a linear lewis structure there is a hybridization of sp. This has an s character of 50% and a p character of 50%. The bond angle is 180. Now if we look at a trigonal planar lewis structure, there is a decreased bond ...

Ana Pedreros

it is sp3d because BrF3 forms three bonds with flourine and has two lone pairs. This T- Shaped structure needs at least 5 orbitals to fit in the 10 electrons, so it uses a d orbital to accommodate it.

Ana Pedreros

Pointing to corners basically means that the arrow displaying a dipole moment points out toward the most electronegative atom. The atoms arrange themselves in a way that each one is the same distance apart and create geometrical shapes that have corners.

Ana Pedreros

The VSEPR theory can predict the geometry shape of a molecule by indicating the alignment of the atoms based on the repulsion among the pairs of electrons around a central atom.

Ana Pedreros

That is correct. The larger the atomic radius, the less dissociation energy is needed to break the bond. This is because a longer bond length between two atoms, resulting from the increased distance between two nuclei, requires less energy to be broken.

Ana Pedreros

There can only be one sigma bond between two atoms and if theres another bond, its a pi bond. There can be up to two pi bonds and one sigma bond between two atoms in a molecule.

Ana Pedreros

A cation has high polarizing power because they can exert a strong pull on the anions electrons. The smaller the radius, the closer the distance between the two ions, and the stronger the distortion of the electrons towards the cation. The trend in the periodic table is that it increases from left t...

Ana Pedreros

A modern way to draw a dipole moment is also drawn by pointing an arrow towards the partial positive charge

Ana Pedreros

Would we still multiply it by 2 if we are just given the velocity like 10 m/s?

Ana Pedreros

Im pretty sure you are right if you are analyzing these molecules as atoms, however, if they are molecules, C2 would have to have a quadruple bond and the negative charge would indicate an extra unpaired electron.

Ana Pedreros

Is the change in energy in an electron still negative, even if it goes from N=1 to n=3?

Ana Pedreros

Does that mean that groups 1A and 7A are all radical?

Ana Pedreros

They are very similar but these terms cannot be used interchangeably because electron affinity is a property of atoms, while electronegativity is a property of atoms when they form bonds with other atoms.

Ana Pedreros

Adding electrons would only create a stronger pull of the electrons towards the nucleus if protons were added as well. The addition of electrons causes a electrostatic repulsion that makes the shell in an anion expand.

Ana Pedreros

Increasing the number of electrons would lead to the orbital expanding in ions. However, the periodic trend refers to neutral atoms, so protons are also added along with the electrons leading to a greater attraction between the nucleus and shell. This causes the shell to contract and the atom gets s...

Ana Pedreros

An Atom emits light when it goes from a higher energy to a lower energy level. An electron absorbs energy when it is excited and moves to higher energy levels.

Ana Pedreros

$E=hc/\lambda$ is one of the equations that I don't think will be given

Ana Pedreros

We're probably expected to understand electron configuration and how orbitals are structured in order to name the state of an electron

Ana Pedreros

Would the number of photons affect the amount of energy produced at a certain wavelength?

Ana Pedreros

how would you model the atom in the second part of this question?

Ana Pedreros

Lines in the Balmer series of the hydrogen spectrum are observed at 656.3, 486.1, 434.0, and 410.2 nm. What is the wavelength of the next line in the series?
im not sure how to approach this question

Ana Pedreros

Lines in the Balmer series of the hydrogen spectrum are observed at 656.3, 486.1, 434.0, and 410.2 nm. What is the wavelength of the next line in the series?
I'm very confused on how to relate these wavelengths

Ana Pedreros

My way to approach this problem was to: 1. figure out the frequency using the wavelength of 102.6 nm and the formula v=c/lambda 2. then use the frequency and plug it into Rydberg formula 3. since the problem states its in the UV spectrum the initial energy should be 1 leaving n2 as the only undefine...

Ana Pedreros

The molar mass of the metal hydroxide M(OH) is 74.10 g/mol.What is the molar mass of the sulfide of this metal?

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