CHEMISTRY COMMUNITY

Miriam Villarreal 1J

In a chemical reaction, the transition state is defined as the highest-energy state of the system. If the molecules in the reactants collide with enough kinetic energy and this energy is higher than the transition state energy, then the reaction occurs and products form. Therefore since this is fair...

Miriam Villarreal 1J

Half-life of second order reactions decrease at a much faster rate. Length of half life increases as you go down while the concentration of substrate constantly decreases, unlike zero and first order reaction.

Miriam Villarreal 1J

saturating the amount of substrate with catalyst does not speed up the rate of the reaction

Miriam Villarreal 1J

the half-life of zero order reaction decrease as the concentration decrease
the half life of a first order reaction is independent of its initial concentration.
the half-life of a second order reaction only depends on the initial concentration and the rate constant.

Miriam Villarreal 1J

As a substances absorbs heat the particles move faster so the average kinetic energy and therefore the temperature increases

Miriam Villarreal 1J

The instantaneous rate of reaction is the slope of the line (the tangent to the curve) at any time t. If you must find concentration at one specific point instead of at a range of times then draw the best tangent to the line and extend it to convenient points on the axis

Miriam Villarreal 1J

Average rate involves seeing how much reactant or product you make over time (average rate of consumption/formation). Unique rate involves dividing the concentration over time by the stoichiometric coefficient . Average looks at one particular time range

Miriam Villarreal 1J

Emf is given a positive value if the cell reaction is spontaneous. This implies that the electrode on the left forces electrons into the external circuit and the electrode on the right withdraws them On the other hand, Emf is given a negative value if the cell reaction is nonspontaneous. This implie...

Miriam Villarreal 1J

standard potentials is the tendency for a chemical species to be reduced, and is measured in volts at standard conditions. The more positive the potential is the more likely it will be reduced.

Miriam Villarreal 1J

Ecell = cell potential at non-standard state conditions which can be derived from Ecell = Eocell - (RT/nF) ln Q
Eocell = standard state cell potential and can be derived from Eocell=RTlnk

Miriam Villarreal 1J

Nernst equations is used to find Ecell under non-standard conditions. when you are given the Ecell°potential you subtarct it from RT/nF and multiply times ln Q

Miriam Villarreal 1J

In acidic solutions, you have to utilize the H+ and H20 to balance

Miriam Villarreal 1J

follow up for this question.. what would be the number of moles to obtain delta G?

Miriam Villarreal 1J

Gibbs free energy (ΔG) equals the work exchanged by the system with its surroundings, (-) minus the work of the pressure force. (When a system changes from initial to Final state).

Miriam Villarreal 1J

In addition ,The relative reactivities of different half cells can be used to compare the direction of electron flow. A higher means there is a greater tendency for reduction to occur, while a lower one means there is a greater tendency for oxidation to occur.

Miriam Villarreal 1J

yes always make sure the solid is on the outermost side as well as making sure it is the anode that is on the left side and cathode on the right

Miriam Villarreal 1J

H20 and H+ are used to balance a redox rxn when substances are placed in an acidic solution whereas H2O and OH- is used to balanced substances in a basic solution.

Miriam Villarreal 1J

A reducing agent is a substance that causes another substance to gain electrons. That said, to identify A reducing agent, it must lose electrons and is oxidized in the chemical reaction. A reducing agent is typically in one of its lower possible oxidation states, and is known as the electron donor.

Miriam Villarreal 1J

There are more ways that the energy can exist in the high entropy state than in the low entropy state. The second law in fact requires the first law to be true, otherwise entropy could spontaneously decrease in a process that destroys energy.

Miriam Villarreal 1J

The entropy of the surroundings will increase if energy (heat) is flowing into the surroundings from the system.If we are given the entropy changes of the system and surroundings, we can calculate total entropy change. The total entropy change is simply the sum of the system and the surroundings

Miriam Villarreal 1J

a spontaneous processes is one that occurs without the addition of external energy. A spontaneous process may take place quickly or slowly, because spontaneity is not related to kinetics or reaction rate.

Miriam Villarreal 1J

The equation expresses the temperature dependence on the equilibrium constant K of a chemical reaction

Miriam Villarreal 1J

∆G is the change of Gibbs (free) energy for a system and ∆G° is the Gibbs energy change for a system under standard conditions (1 atm, 298K). ... Where ∆G is the difference in the energy between reactants and products. In addition ∆G is unaffected by external factors that change the kinetics of the ...

Miriam Villarreal 1J

If you increase temperature, you increase entropy because ..
(1) More energy put into a system excites the molecules and the amount of random activity.
(2) As a gas expands in a system, entropy increases.
(3) When a solid becomes a liquid, its entropy increases.

Miriam Villarreal 1J

A constant-pressure calorimeter measures the change in enthalpy of a reaction occurring in a liquid solution. In that case, the gaseous pressure above the solution remains constant, and we say that the reaction is occurring under conditions of constant pressure.

Miriam Villarreal 1J

Since we are deriving a change in volume volume known as delta the d is representative of that

Miriam Villarreal 1J

I’m addition free expansion of a gas is an irreversible process because the temperature of a gas undergoing a free expansion is not a meaningful quantity.
Also. When talking about an isothermal free expansion of a gas, we mean that the final temperature is the same as the initial temperature.

Miriam Villarreal 1J

In equilibrium, the entropy of the system cannot increase (because it is already at a maximum) and it cannot decrease (because that would violate the second law of thermodynamics).

Miriam Villarreal 1J

Gibbs free energy change determines if a reaction is spontaneous under the conditions of constant pressure and constant temperature

Miriam Villarreal 1J

Enthalpy is a state function because it depends only on two thermodynamic properties such as temperature and pressure, or temperature and entropy, or any pair of other state functions. Not on the process it took to get there

Miriam Villarreal 1J

states that heat is a form of energy, and thermodynamic processes are therefore subject to the principle of conservation of energy

Miriam Villarreal 1J

The work obtained in a reversible is a maximum for the process while the work obtained in a irreversible is not

Miriam Villarreal 1J

The use alternative fuels as an energy source is intended to address concerns about fossil fuels, such as its high carbon dioxide emissions, which is an important factor in global warming.

Miriam Villarreal 1J

Enthalpy encompasses the heat absorbed or evolved in a reaction

Miriam Villarreal 1J

q is the amount of heat transfered to the system. It is one of the two means of energy transfer during most processes studied in thermodynamics. Delta h is a thermodynamic potential, much like internal energy (E). It is essentially a measure of the potential energy of the system

Miriam Villarreal 1J

Heat is the form of energy transfer from a high temperature to a lower temperature. Enthalpy is the heat transfer at a constant pressure.

Miriam Villarreal 1J

in the equation ΔU=q+w w=0 and ΔU=q. The internal energy itself , NOT the change is equal to the heat of the system.

Miriam Villarreal 1J

A state function is a property whose value does not depend on the path taken to reach that specific value. In contrast, functions that depend on the path from two values are call path functions. Both path and state functions are often encountered in thermodynamics.

Miriam Villarreal 1J

During the phase change, when solid melts into liquid, its temperature remains constant as the heat energy is stored as potential energy.

Miriam Villarreal 1J

CV is the specific heat at constant volume, and CP is the specific heat at constant pressure. Specific heat is the heat energy required to raise the temperature of a substance (per unit mass) by one degree Celsius. The main difference between CV and CP is that the volume change is zero for a system ...

Miriam Villarreal 1J

Most chemical reactions occur at constant pressure, so enthalpy is more often used to measure heats of reaction given off or absorbed during a chemical reaction at constant pressure. However The heat given off or absorbed when a reaction is run at constant volume is equal to the change in the intern...

Miriam Villarreal 1J

Q<K means there are more reactants than products therefore in order to reach equilibrium more product is needed and therefore rxn will shift to the right (forward) Q>K means that there are more products than reactants therefore in order to reach equilibrium more reactant is needed and therefore rxn ...

Miriam Villarreal 1J

A buffer solution is one which resists changes in pH when small quantities of an acid or an alkali are added to it. An acidic buffer solution is simply one which has a pH less than 7. Acidic buffer solutions are commonly made from a weak acid and one of its salts - often a sodium salt

Miriam Villarreal 1J

For a gas phase reaction, we express equilibrium constant by pressures, and when there is 1 gas it is the total pressure whereas 2 more gases are referred to as partial gas of each gas implying that the sum of them will make up the total pressure.

Miriam Villarreal 1J

1.20x(0.001) or 10^-3/.500L= SO2 0.50x(0.001) or 10^-3/.500L=O2 0.10x(0.001) or 10^-3/.500=SO3 set up the reaction quotient to calculate Qc (product/reactant) (0.0002)^2 _________________ = 6.94 (.001) x (.0024)^2 since this value is more than the provided Kc, more product (SO3)will form shifting to...

Miriam Villarreal 1J

Volume has no effect on K because a change in volume – a decrease in volume causes an increase in pressure. To reduce the pressure, the system will try to reduce the number of gas molecules and the reaction will shift to the side with fewer gas molecules.

Miriam Villarreal 1J

When there is an increase in pressure, the equilibrium will shift towards the side of the reaction with fewer moles of gas. When there is a decrease in pressure, the equilibrium will shift towards the side of the reaction with more moles of gas.

Miriam Villarreal 1J

Endothermic processes require an input of energy to proceed and are signified by a positive change in enthalpy. Overall an increase in temp will love the forward reaction favoring the products. Exothermic processes release energy upon completion, and are signified by a negative change in enthalpy, p...

Miriam Villarreal 1J

K measures the extent to which reactants are converted to products. It refers to the reactions ability to reach a point where the concentrations of the reactant and product are unchanging with time, because the forward and backward reactions have the same rate.

Miriam Villarreal 1J

Strong acids have a High KA, however a small pKA meaning it dissociate more in water. In contrast, a weak acid is less likely to ionize and release a hydrogen ion, thus resulting in a less acidic solution. The same goes for a strong base in which they will have a high KB but a small pKB.

Miriam Villarreal 1J

Increasing the pressure by adding an inert gas at constant volume has no effect. This is because what matters for the equilibrium are the partial pressures of the reactants and products

Miriam Villarreal 1J

The greater density of molecules increases the number of collisions. When you decrease the pressure, molecules don't hit each other as often and the rate of reaction decreases. By decreasing the volume available to the molecules of gas, you are increasing the concentration of molecules in a specific...

Miriam Villarreal 1J

According to Le Chatelier's principle, adding additional reactant to a system will shift the equilibrium to the right, towards the side of the products because the frequency of successful collisions of that reactant would increase, allowing for an increase in the forward reaction, and thus the gener...

Miriam Villarreal 1J

Pure solids and liquids are not included in the equilibrium constant expression. This is because they do not affect the reactant amount at equilibrium in the reaction, so they are disregarded. We can't increase the concentration of a pure liquid or pure solid and hence they are omitted from the expr...

Miriam Villarreal 1J

Kc is the equilibrium constant specifically for concentrations and Kp is the equilibrium constant for partial pressures

Miriam Villarreal 1J

Can react as a base and acid and examples include amino acids and proteins, which have amine and carboxylic acid groups, and self-ionizable compounds such as water.

Miriam Villarreal 1J

If the complex (inside brackets) is an anion the prefix -ate must be added at the end of the transition metal and iron is part of the exception that uses the beginning of its elemental symbol Fe(rrate)

Miriam Villarreal 1J

a pi bond is formed when two p orbitals overlap in a side-by-side fashion with the electron density concentrated above and below the plane of the nuclei of the bonding atoms.

Miriam Villarreal 1J

hybridization only takes into account areas of electron density not the strength of bonds (double or triple) therefore they have no effect

Miriam Villarreal 1J

Trigonal Planar, Linear, Square Planar, and Tetrahedral (if it's the same elements) will be non polar since dipoles cancel, but the rest of the shapes will be polar.

Miriam Villarreal 1J

The Ka value is the acid dissociation constant which determines a strong or weak acid. A higher Ka will, result in a stronger acid (more hydrogen ions)

Miriam Villarreal 1J

A conjugate base is formed when an acid donates a proton (H+) and conjugate acid is formed when a base accepts a proton. Also if an acid is strong then conjugate base is weak and is a base is strong then conjugate acid is weak

Miriam Villarreal 1J

A couple examples of oxoacids can include Sulfuric acid (H2SO4), phosphoric acid (H3PO4), and nitric acid (HNO3) which suffice in completing one hydrogen, one oxygen, and one other element.

Miriam Villarreal 1J

Strong acids are defined as those that can dissociate by donating an H+ and therefore a long bond which is farther apart and weaker (easier to break) allows for this while a shorter bond doesn't considering it is stronger therefore harder to break.

Miriam Villarreal 1J

When the Cl-, Br-, and I- anions are placed in water they are stable and remain in their state without pulling an H away from H20. Therefore they are known to be less electronegative (weaker bond), and a weaker bond is directly associated with a stronger acid.

Miriam Villarreal 1J

The greater forces of attraction will result in higher boiling and melting points because It takes more energy to separate the molecules from each other. Meanwhile a nonpolar molecule such as is symmetrical and has no positive or negative end.

Miriam Villarreal 1J

dipole dipole occurs between polar molecules (partial negative and partial positive) while induced dipole attraction is a weak attraction that results when a polar molecule induces a dipole in an atom or in a nonpolar molecule by disturbing the arrangement of electrons in the nonpolar species. (ther...

Miriam Villarreal 1J

Ligands in biological process trigger signals and have the ability to bind to the active site of a protein through intermolecular forces (ionic bonds, hydrogen bonds, Van der Waals forces).

Miriam Villarreal 1J

Only lone pairs present on the central atom are considered when determining shape an dcounting the number of areas with e- density.

Miriam Villarreal 1J

if all the outer atoms are the same and symmetric, the dipole moments cancel each other out and become nonpolar. However, a molecule with an unsymmetric shape will be (at least slightly) polar. Additionally lone pair or pairs of electrons on the central atom guarantee a nonuniform distribution of el...

Miriam Villarreal 1J

Bonding pairs are slightly farther away from the central atom compared to lone pairs which utilize their higher repulsion to push the bonding pairs close together , taking up more space since they tend to be closer to the nucleus.

Miriam Villarreal 1J

A hydrogen bond is one of the stronger dipole dipole interactions due to the difference in electro negativity when bonding with fluorine oxygen or nitrogen. However in its totality is one of the weaker forces considering how easy they are to break when compared to covalent/ ionic bonds

Miriam Villarreal 1J

The idea that molecular geometry affects boiling point involves the concept that the less complex the shape the easier it will be for molecules to move freely

Miriam Villarreal 1J

Dipole dipole interaction have a significant effect only when the molecules involved are close together (touching or almost touching). Therefore since polar bond involve the attraction between the negative and positive end of an atom this causes a greater interaction.

Miriam Villarreal 1J

The more strongly an atom attracts the electrons in its bonds, the larger its electronegativity. Electrons in a polar covalent bond are shifted toward the more electronegative atom which is the one with the partial negative charge and results in a positive charge in the other atoms which is stronger...

Miriam Villarreal 1J

Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. Therefore a small electronegativity difference leads to a polar covalent bond and large electronegativity difference leads to an ionic bond.

Miriam Villarreal 1J

In a fully covalent bond, you only have the mixing of the orbitals, as you said. But it's not only that, you also have coulomb interactions between the nuclei, that slightly raise the energy of the molecular orbitals, which results in asymmetric energies. In a fully ionic bond you also have a coulom...

Miriam Villarreal 1J

The relationship between polarizability and the factors of electron density, atomic radii, and molecular orientation is as follows: 1. The greater the number of electrons, the less control the nuclear charge has on charge distribution, and thus the increased polarizability of the atom. 2. The greate...

Miriam Villarreal 1J

The positively charged protons in the nucleus attract the negatively charged electrons. As the number of protons in the nucleus increases, the electronegativity or attraction will increase. Therefore electronegativity increases from left to right in a row in the periodic table

Miriam Villarreal 1J

velocity is measured in m/s and corresponds with c which is equal to 3.0 x 10^8 while frequency has units (hz or s^-1) and is obtained by dividing c over wavelength or by dividing energy by planck's constant (h-6.626 x 10^-34).

Miriam Villarreal 1J

Polarization in ionic bonds refers to the electron cloud distortion of the ions. when a cation is highly charged it will exert a strong electrostatic attraction on the e- of the anion and distort the electron cloud. If the anion has a large electron cloud it will be easily distorted. The greater the...

Miriam Villarreal 1J

Highly distorted electrons are described as being HIGHLY POLARIZABLE, which results in an ionic bond with more covalent characters.

Miriam Villarreal 1J

In order to determine the order of weakest bonds it is important to identify which are the larger atoms (ionic radius=decrease left to right and increase top to bottom) because the larger atoms have a larger distance therefore longer bond length which is weaker and easier to break.

Miriam Villarreal 1J

Non-polar bonding involves the equal sharing of electrons between identical non-metal atoms, polar bonding is the unequal sharing of electrons between two different non metal atoms. Ionic bonding is on one extreme with a complete transfer of electrons forming charged ions.

Miriam Villarreal 1J

Covalent bond normally occur between two nonmetal atoms or between a metalloid and nonmetal which can be determined by looking at the periodic table. On the other hand an ionic bond occurs between a metal and nonmetal which infers that they have completely opposite charges leading one of the atoms t...

Miriam Villarreal 1J

The central atom is usually the one with the element of lowest electronegativity, and halogens and hydrogen are usually terminal meaning the surrounding that you might have multiple of.

Miriam Villarreal 1J

Since covalent bonds involve the sharing of electrons in order to complete an octet, the atoms never have as high of an electronegativity as ionic bonds which involve the complete transfer of electrons.

Miriam Villarreal 1J

Electron affinity increases upward for the groups and from left to right across periods of a periodic table because the electrons added to energy levels become closer to the nucleus, thus a stronger attraction between the nucleus and its electrons.

Miriam Villarreal 1J

Since Resonance structures lie on the fact that a molecule is able to have two or more valid electron dot structures. therefore in calculating the average (hybrid) of the structures, it will be more stable compared to a single bond.

Miriam Villarreal 1J

The number of valence electrons is obtained by knowing its group number which you can identify by looking at the periodic table ad counting the rows that run down vertical. However if you want to know the general number of total electrons in all shells you look at the atomic number of the element.

Miriam Villarreal 1J

Nodal planes are the areas where the probability of finding electrons is zero. The two types of nodal planes are radial nodes and angular nodes.

Miriam Villarreal 1J

The Stern and Gerlach Experiment Electron Spin was meant to utilize silver atoms which have one unpaired electron and pass them through an atom beam that goes through a magnet and arrives at a collection plate that received an upper and lower spin from two different electrons. these spins are identi...

Miriam Villarreal 1J

If the photon energy matches that of the work function (phi) then the electron only has sufficient energy to be ejected not to be fully removed from metal.

Miriam Villarreal 1J

Electromagnetic radiation has properties of particles because is characterized as being a form of light which is absorbed in discrete units (photons)

Miriam Villarreal 1J

For part (b) you covert the 5.00mg into .005g Na and divide it by its molar mass of 23g/mol and multiply the answer you get by 6.02 x 10^23 atoms which should result in 1.31x10^20 atoms which you then multiply by the energy obtained in part a and you should get 44.1J. For part (c) you take the 1.00 ...

Miriam Villarreal 1J

Light is absorbed/emitted in discrete units (quanta or photons).Atoms and Molecules only absorb or emit unique frequencies that are allowed by their unique electronic structure (unlike black bodies that absorb and emit all frequencies).

Miriam Villarreal 1J

Since light doesn't behave like a classical wave that is (bigger wave=more intensity). The only way to obtain an emitted electron is to have the energy of a photon be greater than the energy needed to remove an electron. Light sources (short wavelength=high frequency) can eject e- even with low inte...

Miriam Villarreal 1J

Electrons have discrete energies with only certain wavelengths allowed inside one atom. Therfore the wave moel explains why electrons have quantized energy states in atoms

Miriam Villarreal 1J

electron excitation involves the idea that electrons absorbs a particle of light (photon) and move up to a higher energy level hence the word 'excited'.

Miriam Villarreal 1J

Electrons in the outermost shell have the greatest amount of potential energy because as we know potential energy is defined by energy which an object has because of its position/location, also referring to energy from net electrical charge or stored. Therefore in order to move an electron from an i...

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