Search found 90 matches

by Justin Zhang_1A
Sun Feb 28, 2021 11:14 pm
Forum: *Electrophiles
Topic: Anode vs Cathode
Replies: 12
Views: 23

Re: Anode vs Cathode

Oxidation occurs at the anode while reduction occurs at the cathode.
by Justin Zhang_1A
Sun Feb 28, 2021 11:12 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: n in ∆G = -nFE
Replies: 54
Views: 128

Re: n in ∆G = -nFE

n should be the number of electrons that is transferred in the overall reaction.
by Justin Zhang_1A
Sun Feb 28, 2021 10:04 pm
Forum: Balancing Redox Reactions
Topic: states of matter
Replies: 52
Views: 108

Re: states of matter

Yes, you should include the proper phases for matter.
by Justin Zhang_1A
Sun Feb 28, 2021 9:08 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: E vs E naught
Replies: 26
Views: 56

Re: E vs E naught

E naught is E at standard conditions, so 1 M and 1 atm.
by Justin Zhang_1A
Sun Feb 28, 2021 6:11 pm
Forum: Balancing Redox Reactions
Topic: Oxidation vs Reduction
Replies: 30
Views: 66

Re: Oxidation vs Reduction

When oxidation occurs, there is a loss of electrons. When reduction occurs, electrons are gained.
by Justin Zhang_1A
Sun Feb 21, 2021 9:22 pm
Forum: Balancing Redox Reactions
Topic: Reducing vs oxidizing agents
Replies: 16
Views: 40

Re: Reducing vs oxidizing agents

Oxidizing agents are the ones being reduced, so they gain electrons. Reducing agents are being oxidized, so they lose electrons.
by Justin Zhang_1A
Sun Feb 21, 2021 9:18 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: STP (standard temperature and pressure)
Replies: 8
Views: 36

Re: STP (standard temperature and pressure)

Temperature at STP is 273 Kelvin, which is 0 degrees Celsius.
by Justin Zhang_1A
Sun Feb 21, 2021 9:10 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: delta U=0
Replies: 11
Views: 45

Re: delta U=0

Temperature doesn't change in isothermal processes, so there is no heat or energy being transferred, so delta U is 0.
by Justin Zhang_1A
Sun Feb 21, 2021 8:54 pm
Forum: Calculating Work of Expansion
Topic: Negative Work
Replies: 20
Views: 80

Re: Negative Work

If work is negative then that means that the system is doing work on its surroundings, so it is losing energy.
by Justin Zhang_1A
Sun Feb 21, 2021 8:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Q and K
Replies: 36
Views: 81

Re: Q and K

If K is greater than Q, then products are favored and the reaction proceeds forwards. If K is less than Q, then the reactants are favored and the reaction likely proceeds in reverse.
by Justin Zhang_1A
Sun Feb 14, 2021 6:38 pm
Forum: Van't Hoff Equation
Topic: Celcius vs Kelvin for T1 and T2
Replies: 63
Views: 312

Re: Celcius vs Kelvin for T1 and T2

You should always use Kelvin unless the question explicitly states to use Celsius.
by Justin Zhang_1A
Sun Feb 14, 2021 6:18 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: n in q=nCdeltaT
Replies: 16
Views: 43

Re: n in q=nCdeltaT

n refers to moles, but you can also use grams depending on your specific heat capacity.
by Justin Zhang_1A
Sun Feb 14, 2021 4:01 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy: kJ or J?
Replies: 30
Views: 100

Re: Entropy: kJ or J?

Entropy is usually in J/K, but it may depend on the problem.
by Justin Zhang_1A
Sun Feb 14, 2021 12:21 pm
Forum: Calculating Work of Expansion
Topic: Positive vs. Negative Work
Replies: 22
Views: 63

Re: Positive vs. Negative Work

Yes, positive work means that work is done on a system, while negative work means that the system is doing the work.
by Justin Zhang_1A
Sun Feb 14, 2021 12:16 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Kelvin conversion
Replies: 40
Views: 105

Re: Kelvin conversion

Just adding 273 to the temperature in Celsius should be fine for this class.
by Justin Zhang_1A
Sun Feb 07, 2021 4:46 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Sapling #20 Linear vs. nonlinear molecules
Replies: 13
Views: 62

Re: Sapling #20 Linear vs. nonlinear molecules

Yes, use the VSEPR theory to draw the shape and see if it is linear or nonlinear.
by Justin Zhang_1A
Sun Feb 07, 2021 3:58 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: External Pressure
Replies: 32
Views: 63

Re: External Pressure

External pressure is the pressure pushing on the piston since it is the pressure acting on the system.
by Justin Zhang_1A
Sun Feb 07, 2021 3:41 pm
Forum: Ideal Gases
Topic: R ideal gas constant
Replies: 25
Views: 65

Re: R ideal gas constant

The different R values are for different units, so you should use the one that fits the units given in the question.
by Justin Zhang_1A
Sun Feb 07, 2021 3:04 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Systems
Replies: 24
Views: 85

Re: Systems

The universe is an isolated system.
by Justin Zhang_1A
Sun Feb 07, 2021 2:01 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Can heat capacities be negative?
Replies: 52
Views: 161

Re: Can heat capacities be negative?

No, heat capacities should always be positive.
by Justin Zhang_1A
Sun Jan 31, 2021 8:55 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Exothermic vs Extothermic
Replies: 13
Views: 45

Re: Exothermic vs Extothermic

Temperature increases when something is exothermic because the system is releasing heat into the surroundings. In an endothermic reaction, the system requires energy from the surrounding, so the surrounding loses heat to the system, so temperature decreases.
by Justin Zhang_1A
Sun Jan 31, 2021 8:52 pm
Forum: Phase Changes & Related Calculations
Topic: Salt
Replies: 19
Views: 48

Re: Salt

Salts can be either acidic, basic, or neutral, depending on what cations and anions make up the salt.
by Justin Zhang_1A
Sun Jan 31, 2021 8:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Making X negligible
Replies: 34
Views: 99

Re: Making X negligible

You can ignore X when the K constant is less than 10^-4.
by Justin Zhang_1A
Sun Jan 31, 2021 7:53 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated System
Replies: 16
Views: 53

Re: Isolated System

A vacuum is an isolated system, but an isolated system just refers to a system that cannot interact with the surroundings outside of the system.
by Justin Zhang_1A
Sun Jan 31, 2021 7:51 pm
Forum: Phase Changes & Related Calculations
Topic: Vapor vs gas
Replies: 96
Views: 261

Re: Vapor vs gas

A vapor and a gas are the same thing
by Justin Zhang_1A
Sun Jan 24, 2021 8:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: approximating
Replies: 10
Views: 45

Re: approximating

X is very small but not quite 0. You can take it out of the denominator because it is so small that it won't affect the original concentration that much. You cannot ignore it in the numerator however or else the K constant would be equal to 0.
by Justin Zhang_1A
Sun Jan 24, 2021 8:07 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: pH of weak acid
Replies: 9
Views: 46

Re: pH of weak acid

You can assume x is insignificant usually when Ka is less than 10^-4, because the subtraction of that amount will hardly impact the concentration.
by Justin Zhang_1A
Sun Jan 24, 2021 6:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: X Approximations
Replies: 23
Views: 106

Re: X Approximations

If Ka or Kb is less than 10^-4, then you can approximate and ignore the -x.
by Justin Zhang_1A
Sun Jan 24, 2021 5:57 pm
Forum: Phase Changes & Related Calculations
Topic: H and q
Replies: 47
Views: 188

Re: H and q

q refers to heat while H is enthalpy.
by Justin Zhang_1A
Sun Jan 24, 2021 3:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: How to find the H+ from pH
Replies: 12
Views: 60

Re: How to find the H+ from pH

To get H+ concentration from pH, you would just do 10^(-pH).
by Justin Zhang_1A
Sun Jan 17, 2021 5:46 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Endothermic/exothermic reactions and K
Replies: 11
Views: 57

Re: Endothermic/exothermic reactions and K

If a reaction is endothermic and temperature is increased, K will increase. If the reaction is exothermic and temperature is increased, then K will decrease.
by Justin Zhang_1A
Sun Jan 17, 2021 5:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: shifts left or right
Replies: 23
Views: 95

Re: shifts left or right

A shift to the left or right determines whether reactants or products are favored, which tells you if there is more product or reactant formed.
by Justin Zhang_1A
Sun Jan 17, 2021 5:27 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature
Replies: 45
Views: 166

Re: Temperature

You'll need to know if the reaction is exothermic or endothermic, which depends on the delta H.
by Justin Zhang_1A
Sun Jan 17, 2021 5:25 pm
Forum: Ideal Gases
Topic: Inverse Kc [ENDORSED]
Replies: 41
Views: 130

Re: Inverse Kc [ENDORSED]

You'll use the inverse of Kc when you're finding the reverse reaction.
by Justin Zhang_1A
Sun Jan 17, 2021 5:24 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q > K, Q< K
Replies: 25
Views: 100

Re: Q > K, Q< K

If Q > K, then the forward reaction is favored and produces more products. If Q < K, then the reverse reaction is favored with more reactants.
by Justin Zhang_1A
Sun Jan 10, 2021 11:05 pm
Forum: Ideal Gases
Topic: Units of Temperature
Replies: 82
Views: 378

Re: Units of Temperature

Temperature would be in Kelvin.
by Justin Zhang_1A
Sun Jan 10, 2021 11:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K Favors Products or Reactants
Replies: 20
Views: 101

Re: K Favors Products or Reactants

A large K value is anything over 10^3 while a small K value is less than 10^-3, but if a K value is larger than 1, the products are favored, and if the K value is less than 1, the reactants are favored.
by Justin Zhang_1A
Sun Jan 10, 2021 10:46 pm
Forum: Ideal Gases
Topic: PV=nRT
Replies: 74
Views: 523

Re: PV=nRT

P is pressure, V is volume, n is the number of moles, R is the gas constant, and T is the temperature.
by Justin Zhang_1A
Sun Jan 10, 2021 10:45 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H2O
Replies: 44
Views: 334

Re: H2O

You only need to include H2O if it as a gas, but you can omit it when it is in a solid or liquid state.
by Justin Zhang_1A
Sun Jan 10, 2021 10:43 pm
Forum: Ideal Gases
Topic: Inert Gas
Replies: 20
Views: 101

Re: Inert Gas

An inert gas is one of the noble gases which are in group 18 of the periodic table. These gases don't react with other molecules because they already have a full shell of electrons.
by Justin Zhang_1A
Tue Dec 15, 2020 12:40 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Strength of acid
Replies: 12
Views: 112

Re: Strength of acid

Chlorine is more electronegative than iodine, so the anion is more stable, therefore it is more acidic.
by Justin Zhang_1A
Tue Dec 15, 2020 12:38 pm
Forum: Conjugate Acids & Bases
Topic: Oxyacids
Replies: 8
Views: 51

Re: Oxyacids

An oxyacid is an acid that contains an oxygen, where a hydrogen is bonded to an oxygen in the acid. The strength of the acid increases with the number of oxygen atoms are in it.
by Justin Zhang_1A
Tue Dec 15, 2020 12:36 pm
Forum: Naming
Topic: "ferrate"
Replies: 8
Views: 82

Re: "ferrate"

Ferrate would only be used in a coordination compound with iron if the overall compound has a negative charge.
by Justin Zhang_1A
Sat Dec 12, 2020 8:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs Angular
Replies: 20
Views: 143

Re: Bent vs Angular

Bent and angular have the same meaning in regards to shape.
by Justin Zhang_1A
Sun Dec 06, 2020 7:59 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 13
Views: 125

Re: Coordination Number

The coordination number is the number of bonds that are attached to the central metal atom in a complex, and it's important to know this because it helps us to figure out the name and shape of the coordination complex.
by Justin Zhang_1A
Sun Dec 06, 2020 7:47 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Sapling Question #2
Replies: 7
Views: 59

Re: Sapling Question #2

The overall charge of the compound is -1, and the charge of Cl is also -1. Since there are two chlorines, there is a -2 charge, so you would need an oxidation state of +1 for Cu to make the overall charge -1 for the compound.
by Justin Zhang_1A
Sun Dec 06, 2020 7:44 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Finding Coordination Number
Replies: 14
Views: 106

Re: Finding Coordination Number

The coordination number is the number of bonds that the central transition metal forms.
by Justin Zhang_1A
Sun Dec 06, 2020 7:34 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Why is HF not classified as a strong acid?
Replies: 19
Views: 160

Re: Why is HF not classified as a strong acid?

Since F is very electronegative, it is much harder for HF to dissociate into H+ ions, making it a weak acid.
by Justin Zhang_1A
Sun Dec 06, 2020 7:26 pm
Forum: Naming
Topic: -ate
Replies: 17
Views: 116

Re: -ate

-ate should be used when the compound has a negative charge.
by Justin Zhang_1A
Sun Nov 29, 2020 7:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 12
Views: 87

Re: Molecular Shape

The number of lone pairs definitely affect the shape of a molecule, as they change the bond angles. For example, a molecule with 4 regions of electron density with no lone pairs is tetrahedral, while having one lone pair would make it trigonal pyramidal.
by Justin Zhang_1A
Sun Nov 29, 2020 7:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining Molecular Shape
Replies: 9
Views: 52

Re: Determining Molecular Shape

No, the type of bond will not affect the molecular geometry. The molecular geometry can only be impacted by the number of lone pairs.
by Justin Zhang_1A
Sun Nov 29, 2020 7:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: non polar bonds/polar molecules
Replies: 6
Views: 23

Re: non polar bonds/polar molecules

Molecules need polar bonds in order to be polar.
by Justin Zhang_1A
Sun Nov 29, 2020 7:17 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: sapling #12
Replies: 13
Views: 135

Re: sapling #12

Carbon shouldn't exceed the octet rule here, and both C and O should be able to have 8 electrons. One of the hydrogens should be bonded to the oxygen, giving the carbon atom only 4 bonds.
by Justin Zhang_1A
Sun Nov 29, 2020 6:52 pm
Forum: Hybridization
Topic: Sapling #11
Replies: 19
Views: 134

Re: Sapling #11

Each phosphorous has three bonds to oxygen atoms, and one lone pair. Since there are 4 regions of electron density, the hybridization would be sp3.
by Justin Zhang_1A
Sun Nov 29, 2020 6:34 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: sigma vs pi bonds
Replies: 33
Views: 218

Re: sigma vs pi bonds

You can determine sigma and pi bonds depending on whether it is a single, double, or a triple bond. All single bonds only have sigma bonds, whereas a double bond has one sigma bond and one pi bond. Likewise, a triple bond has one sigma bond and two pi bonds. A single sigma bond is flexible, which ma...
by Justin Zhang_1A
Sun Nov 22, 2020 8:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: repulsion strength
Replies: 10
Views: 76

Re: repulsion strength

Lone pairs occupy a larger volume than bonds do, so they push down and exert more force on the other bonded pairs.
by Justin Zhang_1A
Sun Nov 22, 2020 8:36 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear Strucutres
Replies: 6
Views: 28

Re: Linear Strucutres

Linear structures should have bond angles of 180 degrees.
by Justin Zhang_1A
Sun Nov 22, 2020 8:33 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 21
Views: 128

Re: Bond Angles

Bond angles can't be calculated but you can approximate how they'll change based on electron repulsion.
by Justin Zhang_1A
Sun Nov 22, 2020 6:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling Week 7-8 #1
Replies: 8
Views: 30

Re: Sapling Week 7-8 #1

The shape would be trigonal pyramidal since the S has 3 oxygens bonded and one lone pair attached to it.
by Justin Zhang_1A
Sun Nov 22, 2020 6:17 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Character
Replies: 33
Views: 240

Re: Covalent Character

If the difference between the electronegativities is smaller, then the covalent character of the molecule is greater.
by Justin Zhang_1A
Sun Nov 15, 2020 5:21 pm
Forum: Lewis Structures
Topic: Nitrate Ion Lewis Structure
Replies: 6
Views: 27

Re: Nitrate Ion Lewis Structure

Nitrogen has two single bonds and one double bond, and cannot have an expanded octet, so there are no lone pairs. Since it has 5 valence electrons, you can calculate formal charge by doing 5 - (8/2), which gives you a formal charge of +1.
by Justin Zhang_1A
Sun Nov 15, 2020 5:14 pm
Forum: Resonance Structures
Topic: bond length
Replies: 37
Views: 197

Re: bond length

No, bond lengths will be given in problems if we need the exact length. You should still know the relationship between bond length and strength with single, double, and triple bonds though.
by Justin Zhang_1A
Sun Nov 15, 2020 4:58 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Sapling week 5 & 6 #5
Replies: 20
Views: 131

Re: Sapling week 5 & 6 #5

The formal charge for carbon should be -2, since it has 4 valence electrons, and 4 lone and 4 bonded electrons, so 4 - (4 + 4/2) = -2.
by Justin Zhang_1A
Sun Nov 15, 2020 3:36 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 9
Views: 85

Re: Electronegativity

As you go down the periodic table, n increases, which means there are more shells between the valence electrons and the nucleus. This reduces the nucleus's pull on the valence electrons, and makes the valence electrons easier to remove, which is why electronegativity decreases. As you move across th...
by Justin Zhang_1A
Sun Nov 15, 2020 2:57 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Question about Formal Charges
Replies: 5
Views: 20

Re: Question about Formal Charges

It's the sum of of all the formal charges in the molecule.
by Justin Zhang_1A
Sun Nov 08, 2020 5:23 pm
Forum: Formal Charge and Oxidation Numbers
Topic: What do we use formal charges for?
Replies: 15
Views: 52

Re: What do we use formal charges for?

Formal charges are used for determining which Lewis structure of a molecule is the most stable, with it being more stable the closer it is to 0.
by Justin Zhang_1A
Sun Nov 08, 2020 5:11 pm
Forum: Formal Charge and Oxidation Numbers
Topic: formal charge
Replies: 11
Views: 43

Re: formal charge

Yes, because to calculate formal charge, you need to use both the number of lone pair electrons and the number of bonded electrons.
by Justin Zhang_1A
Sun Nov 08, 2020 5:08 pm
Forum: Ionic & Covalent Bonds
Topic: Size of Bonds
Replies: 28
Views: 113

Re: Size of Bonds

Double bonds have more electrons than single bonds, so they exert a stronger force of attraction on the nuclei of the bonded atoms. This draws the atoms closer together and creates shorter bonds.
by Justin Zhang_1A
Sun Nov 08, 2020 5:05 pm
Forum: Trends in The Periodic Table
Topic: atomic and ionic radii
Replies: 3
Views: 32

Re: atomic and ionic radii

The atomic radius is the distance from the nucleus to the valence electron in a neutral atom, or an element in its normal form on the periodic table. The ionic radius is the distance from the nucleus to the valence electron in an ion, whether it is a positive cation that has lost electrons or a nega...
by Justin Zhang_1A
Sun Nov 08, 2020 3:46 pm
Forum: Electronegativity
Topic: Electronegativity trend
Replies: 18
Views: 109

Re: Electronegativity trend

Electronegativity generally increases as it goes across a period from left to right, since there are more protons in the nucleus, which attract the electrons more and make them harder to remove. Electronegativity also decreases going down the group since there are more orbitals to shield the valence...
by Justin Zhang_1A
Sun Nov 01, 2020 4:55 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E.7
Replies: 6
Views: 22

Re: 1E.7

C is the answer, because the final electron should fill the 2s orbital before moving onto the 2p orbital. Since the electron is in the 2p orbital, that means that the atom is in an excited state.
by Justin Zhang_1A
Sun Nov 01, 2020 4:52 pm
Forum: Einstein Equation
Topic: E=hv vs E=hf
Replies: 15
Views: 124

Re: E=hv vs E=hf

V stands for velocity, and the symbol for frequency is the Greek letter nu, which is like an italicized v, so sometimes f is used to avoid confusion.
by Justin Zhang_1A
Sun Nov 01, 2020 4:46 pm
Forum: Quantum Numbers and The H-Atom
Topic: Sapling question 21
Replies: 11
Views: 71

Re: Sapling question 21

So because n = 2, the question is referring to elements in the second row. It's referring to the last electron of the atom, and since there are 8 elements in the row, there can be 8 electrons with n=2.
by Justin Zhang_1A
Sun Nov 01, 2020 4:41 pm
Forum: Properties of Light
Topic: Relationship between wavelength and frequency
Replies: 10
Views: 94

Re: Relationship between wavelength and frequency

Wavelength and frequency are inversely proportional, since they should always equal the speed of light when you multiply them together, so if one increases, then the other should decrease.
by Justin Zhang_1A
Sun Nov 01, 2020 4:39 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Sapling HW Q17
Replies: 18
Views: 149

Re: Sapling HW Q17

Atomic radii of elements increases as you move down the group and decreases as you go across the period.
by Justin Zhang_1A
Sun Oct 25, 2020 8:21 pm
Forum: Properties of Electrons
Topic: rydberg equation
Replies: 8
Views: 64

Re: rydberg equation

So n1 refers to the final energy level the electron ends up at, while n2 is the initial energy level the electron starts at. It's a bit easier to think of it as n(final)-n(initial).
by Justin Zhang_1A
Sun Oct 25, 2020 4:30 pm
Forum: DeBroglie Equation
Topic: n1 and n2
Replies: 15
Views: 59

Re: n1 and n2

For that equation, n2 should be the shell that the electron originally starts at. It's easier to think of it as n(final) - n(initial).
by Justin Zhang_1A
Sun Oct 25, 2020 4:23 pm
Forum: Properties of Electrons
Topic: Experiments/conceptuals we need to know
Replies: 4
Views: 46

Re: Experiments/conceptuals we need to know

You probably shouldn't need to know super specific details of experiments, but just know the basic purposes and ideas behind them.
by Justin Zhang_1A
Thu Oct 22, 2020 10:54 am
Forum: Administrative Questions and Class Announcements
Topic: Scratch Paper for Midterm
Replies: 2
Views: 57

Re: Scratch Paper for Midterm

You should check with your TA specifically, but scratch paper and work won't be submitted, so you should be able to use extra blank sheets.
by Justin Zhang_1A
Thu Oct 22, 2020 10:44 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg Equation and its Fundamental Equation
Replies: 8
Views: 45

Re: Rydberg Equation and its Fundamental Equation

You can use either equation since the test will be multiple choice and your work won't be graded. However, Dr. Lavelle said there could be some questions where E=(-hR)/n^2 would work better.
by Justin Zhang_1A
Sun Oct 18, 2020 11:04 pm
Forum: General Science Questions
Topic: Sig Figs
Replies: 14
Views: 99

Re: Sig Figs

Normally, you should use the same amount of sig figs as the least number of sig figs given in the problem. You should also avoid rounding until the very last step to avoid rounding errors.
by Justin Zhang_1A
Sun Oct 18, 2020 5:00 pm
Forum: Properties of Light
Topic: Conversion Factor - m to nm
Replies: 6
Views: 59

Re: Conversion Factor - m to nm

To convert a meter to nanometers, you would multiply by 1 X 10^-9.
by Justin Zhang_1A
Sat Oct 17, 2020 6:01 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: delta E
Replies: 10
Views: 75

Re: delta E

Delta E is negative when electrons emit light because energy is being released as electromagnetic radiation, whereas a positive delta E would mean that energy is being absorbed.
by Justin Zhang_1A
Thu Oct 15, 2020 11:27 am
Forum: Photoelectric Effect
Topic: How to find kinetic energy from velocity
Replies: 6
Views: 88

Re: How to find kinetic energy from velocity

The formula to calculate kinetic energy with velocity is 1/2 * m * v^2.
by Justin Zhang_1A
Mon Oct 12, 2020 9:26 pm
Forum: Properties of Light
Topic: Photoelectric effect
Replies: 8
Views: 77

Re: Photoelectric effect

It was worded a bit confusingly, but it's basically saying that the energy of the photon must be equal to or greater than the energy required to remove an electron for the electron to be emitted. An electron won't be emitted if the energy of the photon is less than the energy required to remove an e...
by Justin Zhang_1A
Fri Oct 09, 2020 12:23 pm
Forum: Significant Figures
Topic: Scientific notation and significant figures
Replies: 3
Views: 50

Re: Scientific notation and significant figures

So for your examples, 8000.00 actually has 6 sig figs since trailing zeros in numbers with decimals are significant. 8000 would only have 1 sig fig, as trailing zeros without a decimal don't count, so only the 8 is significant.
by Justin Zhang_1A
Fri Oct 09, 2020 12:07 pm
Forum: SI Units, Unit Conversions
Topic: Mole notation
Replies: 7
Views: 96

Re: Mole notation

They are interchangeable and are both acceptable, so it comes down to personal preference.
by Justin Zhang_1A
Wed Oct 07, 2020 5:49 pm
Forum: Significant Figures
Topic: Sapling Question 2
Replies: 14
Views: 113

Re: Sapling Question 2

The 2 should be positive. You need to multiply 2.917 by 100 to get to 291.7, so it should be 10^2 instead of 10^-2
by Justin Zhang_1A
Wed Oct 07, 2020 4:33 pm
Forum: Limiting Reactant Calculations
Topic: Actual and Theoretical yields
Replies: 14
Views: 145

Re: Actual and Theoretical yields

It's highly unlikely that the actual yield would be the same as the theoretical yield, as there are various impurities or side reactions that prevent the reaction from producing the theoretical yield.
by Justin Zhang_1A
Wed Oct 07, 2020 4:07 pm
Forum: Significant Figures
Topic: Clarification on Significant Figures
Replies: 9
Views: 69

Re: Clarification on Significant Figures

So I think zeros to the left of the first non-zero digit are not significant, so 0.034 would only have two sig figs. Trailing zeros in the decimal portion are significant, so 0.340 would have 3 sig figs.

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