CHEMISTRY COMMUNITY

Jarrett Peyrefitte 2K

The w for Kw means it is the equilibrium constant for water.

Ka times Kb is also equal to Kw, which equals to [H30+][OH-].

Jarrett Peyrefitte 2K

ff the K value is smaller than 5% aka 10^-4, then x can be approximated

Jarrett Peyrefitte 2K

Catalysis is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst

Jarrett Peyrefitte 2K

Ka - Acids
Kb - Bases

Jarrett Peyrefitte 2K

Since UCLA officially offered finals remotely, how will the exam be now?

Jarrett Peyrefitte 2K

How does the rate of change of one species in a reaction relate to that of another species?

Jarrett Peyrefitte 2K

Thank you King Lyndon you da best :)

Jarrett Peyrefitte 2K

It would be linear

Jarrett Peyrefitte 2K

Electrolytic cells - non-spontaneous, convert electric energy into chemical energy
Galvanic cells - spontaneous, convert chemical energy into electric energy

Jarrett Peyrefitte 2K

A reaction is exothermic when the reactants have more energy than products. Vice verso for endothermic.

Jarrett Peyrefitte 2K

What is the relationship between standard cell potential and equilibrium constant of a reaction?

Jarrett Peyrefitte 2K

What does each variable in the Nernst Equation represent?

Jarrett Peyrefitte 2K

What is a concentration cell? How does it work? What is an example of one?

Jarrett Peyrefitte 2K

How can you predict if a metal will dissolve in a solution?

Jarrett Peyrefitte 2K

What is the relationship between free energy and cell potential? What is the equation and how is it used?

Jarrett Peyrefitte 2K

What is the relationship between work and cell potential? What is the equation?

Jarrett Peyrefitte 2K

How can you predict the spontaneous direction of a reaction using standard reduction potentials?

Jarrett Peyrefitte 2K

What is a standard cell potential? How do you calculate it given the half-reactions for the cell and the standard potential?

Jarrett Peyrefitte 2K

What is the electrochemical series? What is the information used for?

Jarrett Peyrefitte 2K

Given the description of a cell, how do you write the balanced chemical equation for a redox equation?

Jarrett Peyrefitte 2K

What is an anode and a cathode? How do you identify the direction of flow?

Jarrett Peyrefitte 2K

What is electromotive force? Why does it represent the maximum potential difference?

Jarrett Peyrefitte 2K

What is a galvanic/voltaic cell? How does it work?

Jarrett Peyrefitte 2K

For constant volume, Cv is used.
For constant pressure, Cp is used.

Jarrett Peyrefitte 2K

Cv = Constant volume
Cp = Constant pressure

Jarrett Peyrefitte 2K

Solids and liquids are always excluded regarding K and Q.

Jarrett Peyrefitte 2K

How is delta S related to delta H for a change at a constant temperature and pressure? What is their relationship?

Jarrett Peyrefitte 2K

How does the Gibbs free energy change process relate to the direction of spontaneous reaction?

Jarrett Peyrefitte 2K

How does temperature, volume, state of matter affect the entropy of a substance? Why?

Jarrett Peyrefitte 2K

How do you determine the heat output of a reaction given the temperature change of a calorimeter?

Jarrett Peyrefitte 2K

What is ∆U and ∆H? What are they used for? How are they related?

Jarrett Peyrefitte 2K

What is the environmental impact of burning fossils, and the use of alternative fuels as an energy source?

Jarrett Peyrefitte 2K

What is the first law of thermodynamics? How is it used and why?

Jarrett Peyrefitte 2K

What are the three different types of thermodynamic systems?

Jarrett Peyrefitte 2K

What are the meanings of heat capacity and specific heat capacity?

Jarrett Peyrefitte 2K

What is the standard state of a substance? When is a substance in its standard state?

Jarrett Peyrefitte 2K

How does Hess's Law depend on the fact that enthalpy is a state property?

Jarrett Peyrefitte 2K

why does steam at 100 degrees C cause a worse burn than boiling water at 100 degrees C?

Jarrett Peyrefitte 2K

What are differences between K and Q? What does it mean when one is larger/smaller than the other?

Jarrett Peyrefitte 2K

How do you calculate hydroxide ion concentration from a hydronium ion concentration? and vice versa?

Jarrett Peyrefitte 2K

How does the acidity constant of an acid relate to the basicity constant of its conjugate base?

Jarrett Peyrefitte 2K

How do we calculate the percentage ionization of a weak acid or base?

Jarrett Peyrefitte 2K

What is the conjugate seesaw? How do we use it in problem solving and calculations?

Jarrett Peyrefitte 2K

Why do we omit solids and liquids when writing for Kc and Kp?

Jarrett Peyrefitte 2K

Can someone explain what autoprotolysis is? When does it occur? Why and How?

Jarrett Peyrefitte 2K

Why do solutions of weak acids have higher pH values than solutions of strong acids at the same concentration?

Jarrett Peyrefitte 2K

What are the differences between solutions of strong and weak acids and bases?

Jarrett Peyrefitte 2K

What does each variable/letter represent in the equation PV = nRT?

Jarrett Peyrefitte 2K

How does the value of the reaction quotient allow the direction of non-equilibrium reaction to be predicted?

Jarrett Peyrefitte 2K

When do you use Q and when do you use K? What are the differences between them?

Jarrett Peyrefitte 2K

How do you determine what direction of the reaction goes given K and the concentrations of all reactants and products?

Jarrett Peyrefitte 2K

When do you write the equilibrium constant as Kc? and when do you write the equilibrium constant as Kp?

Jarrett Peyrefitte 2K

Can someone explain step by step on how to calculate the pH of acids and bases?

Jarrett Peyrefitte 2K

Why can rain be acidic? How do you reduce acidic rain?

Jarrett Peyrefitte 2K

What are all the strong acids and strong bases we need to know?

Jarrett Peyrefitte 2K

What is the difference between amphoteric and amphoprotic?

Jarrett Peyrefitte 2K

What are well-known examples of coordination compounds used as chemotherapy drugs?

Jarrett Peyrefitte 2K

What are the biological functions of naturally occurring coordination compounds?

Jarrett Peyrefitte 2K

VESPR is for naming models that are in 3D, how lone pairs repulse each other, and how the molecule is arranged.

Jarrett Peyrefitte 2K

For the Bronstead-Lowry definition:

Bases accept H+

Acids give away H+

Jarrett Peyrefitte 2K

Oxidation is how many electrons is lost from the anion.

Jarrett Peyrefitte 2K

Yes because that is the rule for naming molecules. :)

Jarrett Peyrefitte 2K

A linear molecule has a 180 degree angle while a bent has less than a 120 degree angle

Jarrett Peyrefitte 2K

Hybridization is when atomic orbitals are mixed into hybrid orbitals so that chemical bonding is easier. Basically, electrons can move into new hybrid orbitals and these orbitals are used to create bonds with other hybrid orbitals in different atoms in order to for a molecule.

Jarrett Peyrefitte 2K

Bent molecules have a lone pair, aka "E", compared to linear molecules do not. The lone pairs repel the electrons on the bonded atoms.

Jarrett Peyrefitte 2K

What are the different types of Intermolecular forces/forces? How do you identify them?

Jarrett Peyrefitte 2K

How can you tell the difference between a sigma and a pi bond? What are they?

Jarrett Peyrefitte 2K

How and why do lone pairs affect the bond angles in a molecule, cation, or anion?

Jarrett Peyrefitte 2K

What is hybridization? And how does it arise from atomic orbitals?

Jarrett Peyrefitte 2K

How are you able to tell if a molecule is polar or nonpolar?

Jarrett Peyrefitte 2K

I am confused particularly with part b and c. What is a radical? How do you go about ranking the increasing HCH bond angles as well? "(a) Draw a Lewis structure for each of the following species: CH3+ ; CH4 ; CH3- 2 ; CH2 ; CH2 2+ ; CH2 2- . (b) Identify each as a radical or not. (c) Rank them ...

Jarrett Peyrefitte 2K

I am confused with this question. What is a hybrid orbital? How do I identify one?
"Identify the hybrid orbitals used by the phosphorus atom in each of the following species: (a) PCl 4 1; (b) PCl 6 2; (c) PCl 5; (d) PCl 3"

Jarrett Peyrefitte 2K

Which bonds are stronger, covalent or ionic? What is the conceptual reasoning behind it?

Jarrett Peyrefitte 2K

A delocalized electron is an electron in an atom, ion or molecule not associated with any single atom or a single covalent bond.

Jarrett Peyrefitte 2K

What is the ionization energy periodic trend? And what is the conceptual reasoning behind it?

Jarrett Peyrefitte 2K

Which bonds are the shortest and which are the longest? What is the reasoning behind it?

Jarrett Peyrefitte 2K

What is the periodic trend for electronegativity? Can someone explain why it is the way it is conceptually?

Jarrett Peyrefitte 2K

What's an easy way to find the formal charge without having to write down the equation and plugin the numbers every time?

Jarrett Peyrefitte 2K

How would you know when to use the formal charge equation? In what situations would it be used in?

Jarrett Peyrefitte 2K

Molecules that have exceptions to the octet rule are molecules with an odd number of electrons (ex. NO) , molecules in which an atom or more than one atom have more than 8 electrons (ex. SF6) , and molecules in which an atom or more than one atom have less than 8 electrons (ex. BCl3) .

Jarrett Peyrefitte 2K

Electrons in an orbital is paired when there are two electron with a spin up and spin down in the same orbital. Electrons are unpaired when there is only one electron with a spin up/down in an orbital, as shown in the photo below.

Jarrett Peyrefitte 2K

Resonance is when some lewis structures have multiple bonds in different places of the structure. For example, for the lewis structure for (CO3)2- , the double bond can moved to any of the oxygen atoms.

Jarrett Peyrefitte 2K

Yes, it is when the formal charge is equal to 0 that shows the structure is stable. To find out the formal charge of a structure, you must use this equation:

FC = V - (L + S/2)

Jarrett Peyrefitte 2K

Try and use this chart to help you answer these questions!

Jarrett Peyrefitte 2K

Try and use this chart to help you with future problems like these!

Jarrett Peyrefitte 2K

Can someone explain what resonance is and what the importance of it is?

Jarrett Peyrefitte 2K

To know when to use a double bond, you must find the formal charge by using the equation, FC = V - (L + S/2). When FC does not equal to 0, then you must use a double bond to make the FC equal to 0.

Jarrett Peyrefitte 2K

I am confused on where to start for this problem. What are the steps to find the minimum uncertainty? What do i do with the given numbers?

"A bowling ball of mass 8.00 kg is rolled down a bowling alley lane at 5.00 ± 5.0 m.s?" What is the minimum uncertainty in its position?"

Jarrett Peyrefitte 2K

pz consists of two lobes intersected by the internuclear z axis. A nodal plane exists within the two lobes.

px consists of two lobes intersected by the x axis.

py consists of two lobes intersected by the y axis.

Jarrett Peyrefitte 2K

I am confused on where to start for this problem. What are the steps to find the velocity of a neutron of a certain wavelength? What shpuld i do first?

"What is the velocity of a neutron of wavelength 100. pm? "

Jarrett Peyrefitte 2K

Try using this chart to help you understand how subshells, orbitals, etc. work.

Hope this helps!

Jarrett Peyrefitte 2K

I am struggling with this problem. Can someone explain how to find the orbitals in subshells and what the differences are between l, m, and n?

"How many orbitals are in subshells with l equal to (a) 0; (b) 2; (c) 1; (d) 3? "

Jarrett Peyrefitte 2K

The T in the question stands for "tons" . 1 ton is equal to 1,000 kg. And one kg is equal to 1,000g. To turn this into grams, you can do

2.5t x 1000kg/1t x 1000g/1kg

Jarrett Peyrefitte 2K

To find the empirical formula, you should always turn the percentage values given to you and imagine the sample mass is 100g (Ex. 54.5% --> 54.5 grams) . Then divide by the molar mass, and divide by the smallest value (molecule must have whole atoms) .

Jarrett Peyrefitte 2K

Try to make a list of reactants and products with their respective number of molecules and balance it one by one.

Jarrett Peyrefitte 2K

I am confused on letter b for this problem. What must I do with the given molar mass to get the molecular formula? "Osmium forms a molecular compound with mass percentage composition 15.89% C, 21.18% O, and 62.93% Os. (a) What is the empirical formula of this compound? (b) From the mass spectru...

Jarrett Peyrefitte 2K

I am confused on where to even start for this problem. What is the first step I should take to find the concentration of chloride ions in the solution? "In medicine it is sometimes necessary to prepare solutions with a specific concentration of a given ion. A lab technician has made up 100.0 mL...

Jarrett Peyrefitte 2K

I'm having trouble with letter c in particular. What steps should I take to solve the percentage yield of aluminum chloride? "Aluminum metal reacts with chlorine gas to produce aluminum chloride. In one preparation, 255 g of aluminum is placed in a container holding 535 g of chlorine gas. After...

Jarrett Peyrefitte 2K

I think Lavelle has said if i'm not mistaken only to round sig figs on your final answer.

Jarrett Peyrefitte 2K

Yes it is that simple! So you would 0.3/6 like you said and get 0.05 moles of Br2.

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