CHEMISTRY COMMUNITY

Hannah Pham

The cathode is the negative electrode.

Hannah Pham

You use K when the reaction is at equilibrium and Q if it is not.

Hannah Pham

You determine the value of delta G, and if it is negative, then it is spontaneous

Hannah Pham

Yes, raise the coefficients as the power

Hannah Pham

It represents work done by expansion

Hannah Pham

Yes, zero order reactions do not need any other factors, only the rate constant.

Hannah Pham

The rate limiting step is the slowest step of a chemical reaction that determines the rate at which the overall reaction proceeds.

Hannah Pham

A is the frequency of collisions in the correct orientation.

Hannah Pham

A is the frequency of collisions. You can calculate A using the Arrhenius equation given the other variables, including temperature, activation energy, and equilibrium constant.

Hannah Pham

It is an exothermic reaction when the activation energy of the reactants are higher than the products. If the activation energy of the products is higher than the reactants, then it is an endothermic reaction.

Hannah Pham

Molecularity is the number of molecules or ions that participate in the rate determining step.

Hannah Pham

Oxidizing agents are the ones that oxidize, so the remove electrons, while reducing agents are the ones doing the reducing, so they provide the electrons.

Hannah Pham

Yes, you use platinum if no metals are given as your conductor.

Hannah Pham

The anode is the one being oxidized, which means it is losing electrons, while the cathode is being reduced, which means it is gaining electrons.

Hannah Pham

The anode is losing electrons, making it gain a more positive charge, while the cathode is gaining electrons making it have a more negative charge.

Hannah Pham

The purpose of a salt bridge is to balance the charges between the half cells. The electrons flow from the anode to the cathode.

Hannah Pham

The cathode is where the species are reduced and anode is where the species are oxidized.

Hannah Pham

n is the number of moles of electrons in a balanced half reaction.

Hannah Pham

When E is positive, then delta G is negative, which makes the reaction spontaneous and favorable.

Hannah Pham

Oxidizing agents are the ones that oxidize, so the remove electrons, while reducing agents are the ones doing the reducing, so they provide the electrons.

Hannah Pham

The purpose of a salt bridge is to balance the charges between the half cells. The electrons flow from the anode to the cathode.

Hannah Pham

A spontaneous reaction has a delta G value that is negative (G<0)

Hannah Pham

To calculate K, use gases and aqueous solutions but not solids or liquids.

Hannah Pham

Hydrogen has an oxidation number of +1 when combined with nonmetals but has an oxidation number of -1 when combined with metals. Oxygen can have an oxidation number of -2, -1, or 0.

Hannah Pham

Oxidation is the loss of electrons and reduction is the gain of electrons. You can determine what is being reduced or oxidized is by the change in oxidation numbers of reactants and products.

Hannah Pham

The Van't Hoff Equation can be used to calculate K at different temperatures if enthalpy of reaction is known. It relates the change in equilibrium constant of a chemical reaction to the change in temperature.

Hannah Pham

Equilibrium will not shift because it only take into account gases and aqueous solution not liquids or solids.

Hannah Pham

ΔH = qp when pressure is constant.

Hannah Pham

Yes, balance the equation and the multiply the standard enthalpy of formation of products and reactants by their stoichiometric coefficients.

Hannah Pham

For pressure use atm, then for the overall answer you would get L atm and convert those units to joules using 1 L atm = 101.325 J

Hannah Pham

I think it would be good for you to remember them, especially monoatomic ones.

Hannah Pham

In a closed system, the matter within the system is constant but energy can be transferred from the system to surroundings and vice versa. In an isolated system, neither matter nor energy between system and surroundings are allowed.

Hannah Pham

An extensive property is a property that changes when the amount of matter changes. Examples include mass, volume, and internal energy.

Hannah Pham

When W = 0 there is constant volume, in which there is no expansion or compression because that is when work is done.

Hannah Pham

HF is a weak acid and not a strong acid because it does not completely dissociate in water. The ions it forms during dissociation are too strongly bound to each other for it to be a strong acid.

Hannah Pham

Constant volume and constant pressure means that the volume or pressure does not change during a reaction.

Hannah Pham

You might have made a mistake because you should not have a negative number inside the square root. However, the overall answer when solving the quadratic formula can be positive and negative.

Hannah Pham

Hess's Law states that regardless of the intermediate steps taken in a reaction, the total enthalpy change for the reaction is the sum of each individual changes.

Hannah Pham

Hess's Law states that regardless of the intermediate steps taken in a reaction, the total enthalpy change for the reaction is the sum of each individual changes.

Hannah Pham

If the reaction is exothermic, increase in temperature would cause the reaction to shift left and decrease in temperature would cause the reaction to shift right

Hannah Pham

Enthalpy is a state function because it only depends on initial and final values in the reaction. The path taken to get from the initial to final value does not matter.

Hannah Pham

If reaction is endothermic and there is an increase in temperature, the forward reaction (products) is favored and the equilibrium constant increases.

Hannah Pham

If the reaction consists of all gases then you would use Kp. Kc can be used for gases as well if the gases are given in concentration rather than pressure.

Hannah Pham

If you're given pH or pOH then use [H3O+] = 10^-pH and [OH-] = 10^-pOH to determine concentration, and plug the concentrations into Ka/Kb formula to determine Ka/Kb value.

Hannah Pham

You could convert pKa to Ka, then use Ka = 10^(-pKa). Use the Ka to find [H3O+]. Determine pH by this equation: pH = -log [H3O+].

Hannah Pham

You would X is too small when K < 10^3

Hannah Pham

To determine the equilibrium constant, only gases and aqueous solutions are used. Liquids and solids are not used because pure substances do not change in a reaction.

Hannah Pham

R is the Ideal Gas Constant which has the value of 8.314J/molK.

Hannah Pham

Changes in pressure and volume do not affect value of the equilibrium constant.

Hannah Pham

Kp is for partial pressure, so when your products and reactants are in the gas phase. Kc is for concentration. However, for gases, you can use either Kc or Kp and just convert using the Ideal Gas Law.

Hannah Pham

Q measures the relative amounts of products and reactant present during a reaction at a particular point in time. Q is compared to K, the equilibrium constant, to determine which direction the reaction proceeds. If Q>K, then the reverse reaction is favored and if Q<K, then the forward reaction is fa...

Hannah Pham

Acids are stronger when there is resonance because the electrons are delocalized, in which the charges would be spread out more.

Hannah Pham

The ligand is polydentate if there are more than one lone pairs that the atom can donate to the transition metal it forms a coordination compound with.

Hannah Pham

Mg(OH)2 is a strong base because it is one of the Group 1 and 2 oxide and hydroxides, where those are strong bases.

Hannah Pham

Light acts like a wave when it forms diffraction patterns, in which there is interference in the waves. This was proven in the experiment where light passed through the opening of two slits and forms interference patterns on a screen. The bands were darker where it was between the spot between the s...

Hannah Pham

SO3 can form hydrogen bonds in water because it contains oxygen atoms, which can form a bond with hydrogen atom from the water molecule due to partial charges on the atoms.

Hannah Pham

A polydentate ligand has multiple lone pair donating sites that are bonded to a central atom.

Hannah Pham

Tetrahedral shape is formed when there are four electron densities, which are four bonds with no lone pairs and square planar is formed when there are six electron densities, consisting of four bonds and two lone pairs.

Hannah Pham

When acid and base solutions react, they produce water and a neutral ionic compound, salt, which is composed of a cation (from the base) and and anion (from the acid).

Hannah Pham

A ligand is an atom or molecule that binds to a metal ion through coordinate bonding.

Hannah Pham

A polydentate ligand has more than two lone pair donating sites that are used to bond to a central atom.

Hannah Pham

The bent shape has lone pair on the central atom while the linear shape typically does not have any lone pairs except for the exception of the molecule with 5 electron densities where there are 2 bonds and 3 lone pairs and the molecule with 6 electron densities with 2 bonds and 4 electron densities.

Hannah Pham

Sigma bonds have their electron density along the bond axis, while pi bonds have their electron density above and below the bond axis. Therefore, the pi bonds cannot rotate like the sigma bonds because rotating would break the pi bond.

Hannah Pham

It is possible to determine the molecular shape from AXE formula. The formula corresponds to the number of electron densities, including the lone pairs and bonds, which is then used to determine shape of the molecule.

Hannah Pham

The oxidation number is the number of electrons that an atom gains or loses in order to form a chemical bond with another atom. It shows the total number of electrons that have been removed from an element (positive oxidation state) or added to an element (negative oxidation state) to get to its pre...

Hannah Pham

Dipole-dipole in the solid phase is stronger because there are stronger attractions between molecules than in the gas phase.

Hannah Pham

How do you know if a lone pair lies on the axial or equatorial position?

Hannah Pham

Intermolecular forces are usually temporary such as instantaneous dipole-induced-dipole forces or London dispersion forces, which are forces caused by movements of the electrons in interacting molecules. Dipole-dipole forces are electrostatic interactions of permanent dipoles in molecules.

Hannah Pham

I think we will have to memorize the molecular shapes and bonds angles based off the Lewis structures.

Hannah Pham

Covalent bonds are formed when atoms within a molecule share electrons. Hydrogen bonding is when a partial positive charge of hydrogen atom of one molecule is attracted to another electronegative molecule (O, N, F). Intramolecular bonds are stronger than intermolecular forces, in which hydrogen bond...

Hannah Pham

How do you determine bond angles based off the molecular shape?

Hannah Pham

To determine hybridization, draw lewis dot structure and determine the steric number (the number of atoms bonded to a central atom plus the number of lone pairs attached to it) which will tell you the number of atomic orbitals needed to create a hybrid.

Hannah Pham

Double bonds are stronger than single bonds, characterized by the sharing of four or six electrons between atoms. Double bonds are composed of sigma bonds between hybridized orbitals, and pi bonds between unhybridized p orbitals. Double bonds give additional stability to compounds.

Hannah Pham

The oxidation number is the number of electrons that an atom gains or loses in order to form a chemical bond with another atom. It shows the total number of electrons that have been removed from an element (positive oxidation state) or added to an element (negative oxidation state) to get to its pre...

Hannah Pham

Polarizability results in distortion of the atom. If the degree of polarization is small, an ionic bond is formed, and if the degree of polarization is large, a covalent bond results. The ability of an atom is known as polar power, which is usually the cation, while the tendency of the anion to beco...

Hannah Pham

Yes, that would be typically how you would draw hydrogen bonds. And just make sure that when you draw a hydrogen bond, it must be between a hydrogen atom with a partial positive charge of one molecule and a partial negative atom (either O, N, F) of another molecule.

Hannah Pham

By having covalent character, there is partial sharing of electrons between atoms that have an ionic bond. The degree of ionic versus covalent character of a bond is determined by the difference in electronegativity between the atoms.

Hannah Pham

I think the only difference between them is that coordinate covalent bonds share a pair of electrons and a covalent bonds shares one electron.

Hannah Pham

How do you know when a molecule has an expanded octet? Would you have to just guess and check by determining the formal changes in which it would have to be 0? For example SO3 and SO4. Are there certain elements that tend to have expanded octet?

Hannah Pham

You would convert the moles of water formed to moles of glucose using the balanced equation, then convert the amount you found to grams of glucose. After, you would subtract that from the grams of glucose initially present. To determine how many moles of O2 initially present, use the moles of H20 pr...

Hannah Pham

To find molecules or formula units, you would use Avogadro's number to convert from moles.

Hannah Pham

Ionic bonds are formed when atoms lose or gain electrons and covalent bonds are formed when atoms share electrons. Ionic bonds are stronger than covalent bonds but in water, covalent bonds are stronger than ionic bonds, in which ionic bonds dissociate when in water.

Hannah Pham

Lattice energy is the energy given off when oppositely charged ions in the gas phase come together to form a solid.

Hannah Pham

The polarity of a bond is determined by the electronegativities of the bonded atoms, in which electronegativity is the ability of an atom in a molecule to attract electrons to itself.

Hannah Pham

How do we know how many resonance structures a molecule has?

Hannah Pham

The difference is that electronegativity is the ability of an atom to attract electrons towards itself while electron affinity is the amount of energy released when an atom gains an electron.

Hannah Pham

An anion is an atom that accepts electrons making it have a negative charge and a cation is an atom that donates electrons making it positively charged. Usually cations are metals and nonmetals are anions. An example of a cation is Na+ and an example of an anion is Cl-.

Hannah Pham

The magnetic quantum number labels the different orientation of the orbitals in a subshell.

Hannah Pham

An example would be how orbitals in p subshell could have orientation of px, py, or pz

Hannah Pham

ml describes the different orbitals of a subshell, so the orientation.

Hannah Pham

In Schrodinger's Wave Function, the probability of finding an electron within the region of the atom is determined by squaring the wave function, ψ2, in which the wave function is a set of all the amplitudes.

Hannah Pham

Spin up and spin down refers to the directions in which the electrons are moving. One electron could be spin up (positive spin) and the other would be spin down (negative spin).

Hannah Pham

Electrons are removed from 4s first.

Hannah Pham

A photon is a particle of visible light.

Hannah Pham

Using the De Broglie equation, within what range would there be detectable wavelike properties?

Hannah Pham

Constructive interference is when the waves that meet are in the same direction, which could result in higher peaks. Destructive interference occurs when displacement of the waves that meet are in opposite directions; this could result in lower peaks.

Hannah Pham

You just need to convert the given amount of product to the amount of reactant of CO2 and determine whether the given amount of CO2 in the problem was more or less than what was used up in the reaction. If it was in excess, then the other reactant would have been the limiting reactant. If CO2 was th...

Hannah Pham

K is the temperature in Kelvin and m refers to the wavelength.

Hannah Pham

I think it would be better to use the number of sig figs that are given in the problem rather than the one given by the periodic table.

Hannah Pham

Do you know which method is better or faster?

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