CHEMISTRY COMMUNITY

Tauhid Islam- 1H

Adding water to concentration cells would alter the molarity of the reactants and thus would have a change in the value of the voltage potential. However in a voltaic cell, adding water to either the anode or the cathode would not change E.

Tauhid Islam- 1H

Gibbs's free energy of a system is a measure of the amount of usable energy that can do work in the system. Delta G equaling work max is an equation that describes this very definition. That change in energy (delta G) is how much usable work the system can do (either the work is done on the system o...

Tauhid Islam- 1H

Order is an experimental property that is concerned with kinetics or rate laws and can be any number (fractional, integral or even zero) while molecularity is the theoretical property that is concerned with mechanism and is always an integer excepting zero.

Tauhid Islam- 1H

Enzymes are just biological catalysts. They are able to lower the activation energy for reactions, the lower the activation energy, the faster the rate. The enzymes speed up the reactions by lowering the activation energy.

Tauhid Islam- 1H

Delta U is the change in the internal energy if the system and that is equal to Q (heat added to the system) - W (work done by the system). If delta U is zero, the heat added to the system is the same as the work done by the system. The amount of heat that is added to the system has the same amount ...

Tauhid Islam- 1H

Reaction mechanism are the sequential elementary reactions that occur from reactants going to products. Reaction intermediates are formed in one step and then consumed in a last step of the reaction mechanism. The slowest step in the mechanism is called the rate determining step or rate-limiting step.

Tauhid Islam- 1H

Yes based on the Nernst equation: Ecell= E(standard) +RTln([reducer]/[oxidizer])

Tauhid Islam- 1H

The Gibbs free energy change determines the voltage of an electrochemical cell. This in turn depends on factors such as concentration, gas pressure, and temperature.

Tauhid Islam- 1H

This depicts a zeroth order reactions, and they are possible if there are physical constrains to the system, as an increase in the concentration of reactants does not lead to a change in the rate of the reaction. An example is the decomposition of N2O on a platinum surface to produce N2 and O2. The ...

Tauhid Islam- 1H

A thermodynamic property are either intensive or extensive. Intensive properties are properties that are independent of the amount of of said property while extensive is. The intensive thermodynamic properties are pressure, temperature and density, and extensive are volume and mass.

Tauhid Islam- 1H

When a system changes from a well-defined initial state to a well-defined final state, the Gibbs free energy, ΔG, equals the work done/exchanged by the system with its surroundings, minus the work of the pressure forces.

Tauhid Islam- 1H

If its a galvanic cell, the cell potential is positive so based on that information, you can figure out which half reactio you have to flip and then based on if the electrons lie to the right of the half reaction, you know that that reaction depicts an oxidation, while if the electrons lie to the le...

Tauhid Islam- 1H

The entropy of a system or the disorder of the system has a value at it's ground state that is representative of the degeneracy of the system at absolute zero or when T=0K. This was made under the assumption that at T=0K, all modes of motion stop meaning there is no vibrational, transnational or rot...

Tauhid Islam- 1H

From my understanding, free expansion is the same as a irreversible expansion which is when there is no external pressure on the system. If the system has no external pressure and if the gas is expanding against no external pressure, the gas is said to expand freely. Because there is no expansion ag...

Tauhid Islam- 1H

In electrochemistry, the equations that use the value of n refers to the stoichiometric coefficient of the electrons in the half-reactions that are transferred in the balanced equation.

Tauhid Islam- 1H

Molar heat capacity is a measure of the amount of heat necessary to raise the temperature of one mole of a pure substance by one degree K. Specific heat capacity is a measure of the amount of heat necessary to raise the temperature of one gram of a pure substance by one degree K.

Tauhid Islam- 1H

There are also half- life reactions. For the zeroth order reaction, we use [A]/2k. Then for the 1st order reaction, we have ln2/ k. Then for the 2nd order reaction, the half life is 1/k[A].

Tauhid Islam- 1H

The Gibbs free energy of a system at any moment in time is defined as the enthalpy of the system minus the product of the temperature times the entropy of the system. The Gibbs free energy of the system is a state function because it is defined in terms of thermodynamic properties that are state fun...

Tauhid Islam- 1H

Residual entropy is the entropy that remains after molecules stop moving at 0 degrees kelvin. The entropy lies within the orientation of the atoms of the molecule.

Tauhid Islam- 1H

Gibbs free energy is equal to delta H- T(delta S). Standard gibbs free energy is when things are occurring at a standard state, which is at 25 degrees C and 1 atm.

Tauhid Islam- 1H

The x-axis is time and the y-axis is 1/[A]. By graphing 1/[A] over time this linearizes the function where the concentration of the reactant decreases at a faster rate compared to compared to the first order reactant. The resulting linearized function of graphing 1/[A] over time has a positive slope...

Tauhid Islam- 1H

The rate determining state is the slowest step in a reaction mechanism because it the overall reaction is only moves towards completion until the all steps of the reaction mechanism are completed and that is dependent on the slowest step as that step takes the longest to complete and will complete l...

Tauhid Islam- 1H

Graphically,, you can see that the amount of work done by a reversible expansion is greater that the amount of work done by an irreversible expansion because in a reversible expansion, pressure is not being held constant, so there is a curve that forms and in order to get the area under the curve, y...

Tauhid Islam- 1H

I think that by holding pressure and volume constant, we can observe certain phenomenon through a more systematic, concrete and mathematically fitting lens. Through this experimentation, we are able to learn a lot of chemistry and how certain chemically properties like thermodynamics and the flow of...

Tauhid Islam- 1H

The basic difference between reversible and irreversible processes is that in the reversible process the system remains in thermodynamic equilibrium, while in the irreversible process the system does not remain in thermodynamic equilibrium. Reversible work means that the entire system (including the...

Tauhid Islam- 1H

An ideal gas is defined as one in which all collisions between atoms or molecules are perfectly elastic and in which there are no intermolecular attractive forces. The molecules of the gas can collide with one another, but there are no forces that creates an interaction between the gases.

Tauhid Islam- 1H

If a reaction is kinetically controlled, that means generally, the temperature is low so the reaction is not controlled by thermodynamic properties but by the kinetics or by the rate of products that can be formed. On the other hand, if a reaction is thermodynamically controlled, the reaction is con...

Tauhid Islam- 1H

The stronger the acid, the lower the pH of the solution. You would expect weak acids to have higher pH values. Also pH is equal to -log concentration of H+ ions in the solutions. Because of partial disassociation of weak acids, you get less H+ ions meaning a higher pH in comparison to strong acids t...

Tauhid Islam- 1H

If you have a higher activation energy, more energy will be needed to move the products past that activation energy hump, and because you need more energy, you can assume that inorder for the reaction to progress, you are going to need more time to get past that activation energy if it was higher ra...

Tauhid Islam- 1H

The concentrations of the products and reactants have to not be at equilibrium inorder to generate voltage. If we relate standard cell potential to the equilibrium constant, we get this equation at 25 degrees C: E=(0.0257/n)ln k

Tauhid Islam- 1H

Yes, both forward and backward reactions are slower in lower temperatures and faster in higher temperatures as dictated by the Arrhenious equation.

Tauhid Islam- 1H

This concept was heavily emphasized in thermodynamics, state functions are properties whose values do not depend on the path taken to reach that specific value whereas path functions are functions that depends on the path taken from two values. For state functions, you are only concerned over the fi...

Tauhid Islam- 1H

Yes, they both are the same things but different names. Both have two different metals connected by a salt bridge or a porous disk between the individual half cells.

Tauhid Islam- 1H

I think it was just a matter of identifying which equation you could have used given the constants that were also given on the test. From there, you would have used the values you previously found to calculate the next. Use delta H and delta S to calculate delta G.

Tauhid Islam- 1H

A cell potential is a measure of the potential difference between two half cells (anode and cathode) as electrons from the anode move to the cathode. Changing the concentration of one of the oxidized/ reduced element places the system further out of equilibrium thus changing the cell potential.

Tauhid Islam- 1H

Exothermic reactions produce heat, meaning heat flows from the system to the surrounding so q has to be negative to denote this.

Tauhid Islam- 1H

From my understanding, a reaction is determined by either the thermodynamic properties of the products or the kinetic factors or the rate of product formation. When the temperate is low, there is only enough energy to get past a small activation energy barrier until the reaction proceeds to the righ...

Tauhid Islam- 1H

A zeroth order reaction is when the rate of the reaction is not dependent on the concentration of the reactants. If the concentrations of the reacts increased or decreased, the rat of the reaction would remain the same. This is clearly seen in the graph where concentration of reactants are graphed o...

Tauhid Islam- 1H

I'm pretty sure all standard state quantities are dependent on time. Gibb's free energy change is a function of temperature so at different temperatures, you would have different energies.

Tauhid Islam- 1H

It's also important to know the relationship between whichever manipulation of the initial concentration of a reactant to time is. That relationship will tell you the order of the reaction. From there, the equations are pretty standard. I think the hardest part to figuring out which order the reacti...

Tauhid Islam- 1H

pH=-log(concentration of H3O ions) while pKa=-log(acidity constant which is the ratio between the concentrations of hydronium ions times concentration of the acid's conjugate base divided by concentration of the acid)

Tauhid Islam- 1H

Partial pressures of a gas are also considered concentrations of the gas. ICE tables can be used for both molar concentrations and partial pressure.

Tauhid Islam- 1H

Decreasing H2 in the reaction means overall there are less reactants compared to products and the ratios between products and reactants are not at the equilibrium constant Kc, so inorder to get to the equilibrium ratio, you have to produce more reactants so the reaction shift towards the left, makin...

Tauhid Islam- 1H

If you are just given Kw, then wouldn't the molar concentration of H3O be 1.0*10^-7?

Tauhid Islam- 1H

I think it's because they are dissociated ions in the solution, and not solids or liquids. They are in an aqueous state meaning that the solid dissolved in the solvent (water i believe) and now exists as ions in the solvent.

Tauhid Islam- 1H

Your E row represents the expressions of change the species goes through inorder to reach their equilibrium points. After you calculate x or the change, you plug that into the E row and there you the concentrations of the species at equilibrium.

Tauhid Islam- 1H

When Q is less than K, we know that in the system, there are more reactants compared to products, so for the system to reach the ratios of products to reactants that is detonated by K, the forward reaction is favored where you would end up making more products to get the ratio to be K.

Tauhid Islam- 1H

Melting point and boiling points are determined by how strongly one molecule of a substance is attracted to another molecule of the same substance or another substance, essentially these forces are called intermolecular forces. These stronger these forces, the more energy required to break them and ...

Tauhid Islam- 1H

Wait so the bond between the ligand and the TM doesn't form because of the charges from the TM and the ligand? I thought the bond forms because of the net charges, but I don't really know.

Tauhid Islam- 1H

Look at the lewis structure to help figure out the hybridization of an atom. If a central atom has four areas of electron density around it, then you need a hybridization that corresponds to those four areas. In this case, sp 3 . If an atom has three areas of electron density, the hybridization is ...

Tauhid Islam- 1H

The way I always remember it is by determining the electron geometries by observing the molecule by its areas of election density. This means that if a molecule has two bonds and two lone pairs, the electron geometry is tetrahedral because it has four areas of electron concentration. If the molecule...

Tauhid Islam- 1H

The part that confused me what the induced-dipole induced dipole IMFs. From what I remember from discussion section, the larger the non-polar molecule, the easier it is to disperse the charges within the molecule, making the IMFs stronger, compared to if you had shorter non-polar molecules interacti...

Tauhid Islam- 1H

I'm pretty sure he said that it won't be on test 2 during lecture.

Tauhid Islam- 1H

What does the Energy value that we calculate in the Rydberg's Equation represent? The energy of the emitted EMR? or the energy (gained or lost) of the electron as it is moving between discreet energy levels? Or is it the same?

Tauhid Islam- 1H

Yes, I think the question is trying to convey the concept that when an electron is moving between energy levels, mainly falling from a higher energy level to n=1(Lyman series) and from a higher energy level to a n=2(Balmer series), EMR is emitted in different forms, from visible light to ultraviolet...

Tauhid Islam- 1H

From my understanding, the radius of electron corresponds to its energy level. The farther away the electron is from the nucleus, the greater the radius, meaning the greater the quantized energy level, which corresponds to a specific frequency or wavelength the electron has. The concept is that thes...

Tauhid Islam- 1H

Hello! I'm having trouble understanding what exactly an Absorption Spectra is. I know that its related to spectroscopic experiments which analyzes the relationship between electromagnetic radiation and matter like how light refracts when passing through a prism, but the connections between these exp...

Tauhid Islam- 1H

if i remember correctly, i think Dr. Lavelle said that you can use the De Broglie equation to solve for the frequency of an electron as the equation relates the frequency of an object to its mass and its velocity. This equation would work for any object I believe as all matter has both wave-like and...

Tauhid Islam- 1H

I think it's easier to manage for the TAs if we just submit the five required HW problems. But doing the assigned problems would help your comprehension of the material. I doubt there is any extra credit associated with turning in extra problems, but you can always ask the TAs. It might just be more...

Tauhid Islam- 1H

The Rydberg equation is used in to find the wavelength of light emitted when an electron moves between energy levels. This one of the concepts covered under the quantum mechanics of the atom. is the equation just for when an electron is moving from a higher energy level to a lower energy level, thu...

Tauhid Islam- 1H

M1V1=M2V2 is a concept that means the amount of moles in the solution remains constant whether you are changing the concentration of the solution or the volume of the solution. So by adding water to a solution with a certain morality of a certain molecule or ion, you are increasing the volume of the...

Tauhid Islam- 1H

I think the 100. mL of the diluted solution is referring to 1.00 L of 0.50 m HNO 3 (aq) from part a. So if you have 1L of 0.50M of HNO3, and you are taking 100mL or .1L of that solution and you are trying to figure out how many mL of NaOH you need to neutralize the solution. If you just have HNO3 in...

Tauhid Islam- 1H

So the question is asking for the molarity of each ion in the solution. Knowing that molarity is the amount of moles of ion per liter of the entire solution, you know you have to convert all three KCl, K2S and K3PO4 from grams to moles of K+. Use their respective atomic masses to figure out how many...

Tauhid Islam- 1H

From my understanding in a chemical reaction, there are reactants that are interacting with one another to produce the products. Some of the reactants are used up faster in the chemical reaction compared to the other reactants. Thus, the reactant that runs out the fastest limits how long the reactio...

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