Search found 100 matches

by RasikaObla_4I
Sun Mar 15, 2020 9:30 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Glass Electrode
Replies: 5
Views: 75

Re: Glass Electrode

Glass electrodes are used to measure pH and Ecell measurements are converted to [H+] concentrations.
by RasikaObla_4I
Sun Mar 15, 2020 9:18 pm
Forum: General Rate Laws
Topic: Overall Order
Replies: 6
Views: 96

Re: Overall Order

The overall order is equal to all the exponents on the reactant concentrations added together.
by RasikaObla_4I
Sun Mar 15, 2020 9:06 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Seeing how many electrons transfer
Replies: 2
Views: 70

Re: Seeing how many electrons transfer

Both ways do work, but the easier method is generally to split up the half reactions and balance it that way depending on whether it is a basic or acidic solution.
by RasikaObla_4I
Sun Mar 15, 2020 9:05 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Doing work vs work done
Replies: 8
Views: 126

Re: Doing work vs work done

Work is positive when it is being done on the system (eg. compression) while work is negative the system is doing work on the system (eg expansion).
by RasikaObla_4I
Sun Mar 15, 2020 9:00 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: catalyst
Replies: 4
Views: 81

Re: catalyst

catalysts are used up and then reformed so they start in the reactants of one reaction and are reformed in the products of another reaction.
by RasikaObla_4I
Sun Mar 08, 2020 11:42 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: K’
Replies: 4
Views: 43

Re: K’

k' is the rate constant of the reverse reaction. So at equilibrium, k[A][B]=k'[C][D]
by RasikaObla_4I
Sun Mar 08, 2020 11:35 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: galvanic vs electrolytic
Replies: 12
Views: 84

Re: galvanic vs electrolytic

A galvanic cell have a positive standard Ecell while an electrolytic cell have a negative standard Ecell and it is not spontaneous.
by RasikaObla_4I
Sun Mar 08, 2020 11:08 pm
Forum: General Rate Laws
Topic: General Rate Laws
Replies: 7
Views: 78

Re: General Rate Laws

In the beginning of a reaction, there are no products present so we use the initial concentrations of the reactants because only the forward reaction occurs.
by RasikaObla_4I
Sun Mar 08, 2020 11:03 pm
Forum: General Rate Laws
Topic: Changing the mass of electrodes
Replies: 6
Views: 44

Re: Changing the mass of electrodes

Changing the mass would not affect the Ecell because in the Nernst equation, which is used to calculate the Ecell, the mass is not incorporated into the equation.
by RasikaObla_4I
Sun Mar 01, 2020 11:10 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: units
Replies: 11
Views: 129

Re: units

The units for the rate of a reaction are moles per liter per unit of time.
by RasikaObla_4I
Sun Mar 01, 2020 11:06 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell notation
Replies: 2
Views: 34

Re: Cell notation

The pt(s) is an inert metal inserted as an electrode because the other elements are not solids, so it should not be included in the balanced equation. The other elements in the cell diagram should be included in the balanced equation.
by RasikaObla_4I
Sun Mar 01, 2020 9:26 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: first order
Replies: 8
Views: 109

Re: first order

The graph of ln(reactant) and time is a straight line and the slope is linear.
by RasikaObla_4I
Sun Mar 01, 2020 9:22 pm
Forum: Balancing Redox Reactions
Topic: Cell Diagrams
Replies: 14
Views: 121

Re: Cell Diagrams

The cell diagram is written as the anode (oxidation reaction) first on the left side followed by the cathode (reduction reaction) similar to how a cell would be drawn.
by RasikaObla_4I
Sun Feb 23, 2020 9:03 pm
Forum: Balancing Redox Reactions
Topic: Half reactions
Replies: 17
Views: 194

Re: Half reactions

The half reactions are balanced when they have an equal number of e- charges on the reactant and product sides.
by RasikaObla_4I
Sun Feb 23, 2020 8:54 pm
Forum: Ideal Gases
Topic: Conjugate acid and bases
Replies: 7
Views: 167

Re: Conjugate acid and bases

A conjugate acid is the acid when it loses its H+ ion, so it should have a one less charge than the acid. A conjugate base is the base when it gains an H+ ion, so it should have one more charge than the base.
by RasikaObla_4I
Sun Feb 23, 2020 8:52 pm
Forum: Balancing Redox Reactions
Topic: Balancing in a Basic Solution
Replies: 3
Views: 36

Re: Balancing in a Basic Solution

A basic solution contains less H+ ions, so more OH- ions, so a basic solution should be balanced with the OH- ions.
by RasikaObla_4I
Sun Feb 23, 2020 8:50 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 7
Views: 104

Re: Van't Hoff Equation

The Van't Hoff equation is used to calculate K (equilibrium constant) at different temperatures if the change in enthalpy is known.
by RasikaObla_4I
Sun Feb 23, 2020 8:46 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gp=Gr
Replies: 3
Views: 70

Re: Gp=Gr

At equilibrium, the forward and reverse reactions occur at the same right which means that they are at their lowest energy states. As a result, the Gibbs free energy of the reactants and products has to be the same at equilibrium.
by RasikaObla_4I
Sun Feb 16, 2020 9:52 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibb's Free Energy
Replies: 7
Views: 78

Re: Gibb's Free Energy

Gibbs Free Energy is the amount of free energy available to do work. It is a state function, so only the initial and final amounts matter.
by RasikaObla_4I
Sun Feb 16, 2020 9:46 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Isochoric
Replies: 8
Views: 148

Re: Isochoric

iso means same and choric means volume, so isochoric means constant volume.
by RasikaObla_4I
Sun Feb 16, 2020 9:33 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Delta S
Replies: 8
Views: 182

Re: Delta S

Delta S is the entropy of the system. Delta S surroundings is the entropy of the surroundings. Delta S total is the entropy of the surroundings and system combined.
by RasikaObla_4I
Sun Feb 16, 2020 9:31 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated versus closed
Replies: 7
Views: 162

Re: Isolated versus closed

An isolated system, like combustion in a bomb calorimeter, is when nothing changes with the surroundings. A closed system, like a sealed beaker, is when only energy can exchange with the surroundings.
by RasikaObla_4I
Sun Feb 16, 2020 9:28 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work
Replies: 14
Views: 271

Re: Work

when something is being compressed, work is done by the system, so it is positive. When something is expanding, work is done on a system, so it is negative.
by RasikaObla_4I
Sun Feb 09, 2020 9:02 pm
Forum: Ideal Gases
Topic: Change in pressure
Replies: 7
Views: 131

Re: Change in pressure

Increasing the pressure will shift the reaction to the side with fewer moles of gas and decreasing the pressure will shift the reaction to the side with more moles of gas. If there is an equal number of moles on the reactants and products, then there will be no change.
by RasikaObla_4I
Sun Feb 09, 2020 8:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Le Chatelier's Principle
Replies: 5
Views: 46

Re: Le Chatelier's Principle

When you are expanding a gaseous mixture, you are increasing the volume, so decreasing the pressure, so the reaction would proceed to the side with more moles of gas.
by RasikaObla_4I
Sun Feb 09, 2020 8:56 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: 4G1
Replies: 1
Views: 20

Re: 4G1

The formula for calculating W is (# of microstates)^#atoms/molecules. So for part a, if the nano structure is aligned in the same direction, the number of microstates is 1 and the number of molecules is 64, so W would be 1^64 which is one. For part b, the number of microstates is 4 and the number of...
by RasikaObla_4I
Sun Feb 09, 2020 8:53 pm
Forum: Calculating Work of Expansion
Topic: 4A.3
Replies: 4
Views: 50

Re: 4A.3

Because work is equal to -p delta V, to find the volume of the pump, you need to use the formula for calculating the volume of a cylinder which is pi (r)^2 X height, with the height being -20 because the pump is being compressed. Using the volume and the given pressure, you can plug the values into ...
by RasikaObla_4I
Sun Feb 09, 2020 8:50 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: 4G.1
Replies: 3
Views: 36

Re: 4G.1

If they are all aligned in the same direction, then the microstate would be one.
by RasikaObla_4I
Sun Feb 02, 2020 11:29 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: delta U
Replies: 9
Views: 78

Re: delta U

Change in internal energy is equal to q(heat)+w(work).
by RasikaObla_4I
Sun Feb 02, 2020 11:22 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Types of Systems
Replies: 7
Views: 114

Re: Types of Systems

In a closed system, energy can exchange with the surroundings. An example is a sealed beaker of water.
by RasikaObla_4I
Sun Feb 02, 2020 8:53 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature
Replies: 14
Views: 164

Re: Temperature

A negative delta H is exothermic because energy is released.
by RasikaObla_4I
Sun Feb 02, 2020 8:50 pm
Forum: Calculating Work of Expansion
Topic: Expansion
Replies: 4
Views: 41

Re: Expansion

work of expansion will be a negative value because the change in volume is positive, while work of compression will be a positive value because the change in volume is negative.
by RasikaObla_4I
Sun Feb 02, 2020 8:46 pm
Forum: Ideal Gases
Topic: PV=nRT
Replies: 12
Views: 161

Re: PV=nRT

P is pressure in atm, V is volume in liters, n is the number of moles, R is the gas constant 8.206 x 10-2 L·atm·K-1·mol-1, and T is the temperature in Kelvin.
by RasikaObla_4I
Sun Jan 26, 2020 9:29 pm
Forum: Ideal Gases
Topic: Determining N
Replies: 9
Views: 112

Re: Determining N

Only moles of gas are accounted for because it is the ideal gas law.
by RasikaObla_4I
Sun Jan 26, 2020 9:28 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy is said to be additive
Replies: 10
Views: 99

Re: Enthalpy is said to be additive

Because enthalpies of different reactions can be added together, it is said to be additive.
by RasikaObla_4I
Sun Jan 26, 2020 9:14 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy Calculations
Replies: 5
Views: 35

Re: Enthalpy Calculations

I think you should just know that the enthalpy is positive for all the phase changes.
by RasikaObla_4I
Sun Jan 26, 2020 9:13 pm
Forum: Calculating Work of Expansion
Topic: Work Units
Replies: 3
Views: 29

Re: Work Units

Since work is the energy required to do something, it is measured in joules.
by RasikaObla_4I
Sun Jan 26, 2020 9:04 pm
Forum: Phase Changes & Related Calculations
Topic: enthalpy of phase changes
Replies: 8
Views: 67

Re: enthalpy of phase changes

No because it requires heat energy to go from a solid to a liquid to vapor so the reactions would be endothermic.
by RasikaObla_4I
Sun Jan 26, 2020 9:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Exothermic and Endothermic
Replies: 11
Views: 414

Re: Exothermic and Endothermic

Because an exothermic reaction releases energy and the energy of the products is lower than the energy of the reactants, the enthalpy is negative. An endothermic reaction absorbs energy so the energy of the products is higher than the energy of the reactants, so the enthalpy is positive.
by RasikaObla_4I
Sun Jan 19, 2020 11:53 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H20 in the ICE table
Replies: 26
Views: 231

Re: H20 in the ICE table

Yes, you should leave out H2O because we assume that it is in excess so the concentration doesn't affect the reaction.
by RasikaObla_4I
Sun Jan 19, 2020 11:48 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw
Replies: 2
Views: 17

Re: Kw

The Kw value is a constant value of 1.0 X 10^-14 and it is used to either find the concentration of [OH-] or [H3O+] if either of the concentrations of the acid or base are given.
by RasikaObla_4I
Sun Jan 19, 2020 1:49 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Endothermic vs. exothermic
Replies: 5
Views: 43

Re: Endothermic vs. exothermic

When the temperature increases and the reaction is endothermic, the amount of reactants increases, so to balance out to equilibrium, the reaction will shift towards the products.
by RasikaObla_4I
Sun Jan 19, 2020 1:47 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure
Replies: 5
Views: 41

Re: Pressure

An increase in pressure will favor the side of the reaction with less moles of gas and an decrease in pressure will favor the side of the reaction with more moles of gas. However, if an inert gas is added to the system, there is no change in the reaction.
by RasikaObla_4I
Sun Jan 19, 2020 1:38 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Quadratic Equation
Replies: 8
Views: 77

Re: Quadratic Equation

When doing an ICE table, solving for x requires using a quadratic equation. However, if the K value given is less than 10^-3, then we can assume that the x value in the denominator is so close to zero that we can ignore it.
by RasikaObla_4I
Sun Jan 12, 2020 9:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Reaction Direction
Replies: 14
Views: 253

Re: Reaction Direction

If Q>K then the reaction moves to the left because the concentration of products is greater than the concentration of reactants so the reaction would move towards the side of the reactants to reach equilibrium. If Q<K, then the reaction moves to the right because the concentration of reactants is gr...
by RasikaObla_4I
Sun Jan 12, 2020 9:00 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Partial Pressure
Replies: 19
Views: 131

Re: Partial Pressure

Usually they should be given or you might have to convert from moles to pressure using the ideal gas equation.
by RasikaObla_4I
Sun Jan 12, 2020 8:50 pm
Forum: Ideal Gases
Topic: PV = nRT Confusion
Replies: 4
Views: 67

Re: PV = nRT Confusion

PV=nRT, the ideal gas equation, can be used to solve for any of the values in the equation if a question asks for it or converting between pressure and molarity.
by RasikaObla_4I
Sun Jan 12, 2020 8:42 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp vs Kc usage
Replies: 5
Views: 50

Re: Kp vs Kc usage

Kp is used when the products and reactants are in the gaseous phase. Kc is used when the products and reactants are in the aqueous phase, so they have a concentration.
by RasikaObla_4I
Sun Jan 12, 2020 8:38 pm
Forum: Ideal Gases
Topic: partial pressures
Replies: 7
Views: 69

Re: partial pressures

The ratio (PO2)^3/(PO3)^2 represents the equilibrium constant K so it stays the same. As a result changing the concentrations of the products and reactants would not change the constant.
by RasikaObla_4I
Sun Dec 08, 2019 10:35 pm
Forum: Biological Examples
Topic: Heme complex & O2
Replies: 5
Views: 131

Re: Heme complex & O2

Yes each heme complex binds to one O2- molecule which is why myoglobin only transports one oxygen molecule at a time.
by RasikaObla_4I
Sun Dec 08, 2019 10:32 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: pKa and pKb
Replies: 2
Views: 112

Re: pKa and pKb

It is the negative log of the Ka value. A lower pka indicates that an acid is stronger because it shows that the acid more fully dissociates.
by RasikaObla_4I
Sun Dec 08, 2019 10:31 pm
Forum: Naming
Topic: type of compound
Replies: 2
Views: 106

Re: type of compound

It is an amphoteric oxide because it falls under the amphoteric band on the periodic table.
by RasikaObla_4I
Sun Dec 08, 2019 10:27 pm
Forum: Identifying Acidic & Basic Salts
Topic: Types of Salts
Replies: 4
Views: 152

Re: Types of Salts

No, but you can differentiate between an acidic, normal, and basic salt. A salt formed from a strong acid and weak base is normally acidic and a salt formed from a strong base and a weak acid is normally basic.
by RasikaObla_4I
Sun Dec 08, 2019 10:21 pm
Forum: Naming
Topic: Types of Compounds
Replies: 2
Views: 100

Re: Types of Compounds

If the electronegativity difference between two atoms is greater than 2, then the bond is normally ionic and if the difference is less than 1.5 then the bond is normally covalent.
by RasikaObla_4I
Sun Dec 01, 2019 8:46 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Acid Strength
Replies: 3
Views: 65

Re: Acid Strength

In oxacids, increasing the number of oxygen atoms distributes the negative charge over more atoms so the proton is less attracted to only one oxygen so the acid becomes stronger.
by RasikaObla_4I
Sat Nov 30, 2019 3:18 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Relative Acidity
Replies: 4
Views: 67

Re: Relative Acidity

The more polarizable an anion, the more stable it is, so the more electronegative an atom, the more stable the anion.
by RasikaObla_4I
Sat Nov 30, 2019 3:13 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Ka constant
Replies: 5
Views: 87

Re: Ka constant

The Ka equilibrium constant represents the strength of an acid in a solution based on how well it can dissociate. Lavelle mentioned that if a Ka value is given, it usually indicates that the element is a weak acid because a strong acid that dissociates completely would have a Ka of close to 1.
by RasikaObla_4I
Sat Nov 30, 2019 3:09 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Weak Acids & Bases
Replies: 6
Views: 101

Re: Weak Acids & Bases

Some examples of a weak base are ammonia (NH3) and methylamine (CH3NH2) and examples are a weak acid are carbonic acid (H2CO3) and vinegar (C2H4O2).
by RasikaObla_4I
Fri Nov 29, 2019 7:18 pm
Forum: Bronsted Acids & Bases
Topic: Definition of Bronsted and Lewis
Replies: 1
Views: 30

Re: Definition of Bronsted and Lewis

Examples of a lewis acid, but not a bronsted acid are BF3, AlCl3, and metal cations like Mg2+, Li+, Na+ because they accept an electron pair, but don't necessarily donate a proton.
by RasikaObla_4I
Sun Nov 24, 2019 10:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawing molecules
Replies: 7
Views: 114

Re: Drawing molecules

Drawing the molecules based on its organic structure will not be covered in 14A, so I don't think you will need to know it for the final.
by RasikaObla_4I
Sun Nov 24, 2019 10:35 pm
Forum: Hybridization
Topic: Why does hybridization occur
Replies: 3
Views: 37

Re: Why does hybridization occur

Hybridization occurs when an atom creates a bond using electrons from both the s and p orbitals. As a result, there is an imbalance in the energy levels, so to equalize it, the s and p orbitals are combined to create hybrid orbitals.
by RasikaObla_4I
Sun Nov 24, 2019 10:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles
Replies: 7
Views: 87

Re: Bond angles

The bond angles are less than 120 degrees on the equatorial and less than 90 degrees on the axial.
by RasikaObla_4I
Sun Nov 24, 2019 10:29 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: bronsted acid
Replies: 5
Views: 58

Re: bronsted acid

A bronsted acid is a molecule that gives up a proton, or a hydrogen atom, to another molecule.
by RasikaObla_4I
Sun Nov 24, 2019 10:27 pm
Forum: Hybridization
Topic: sigma or pi?
Replies: 20
Views: 271

Re: sigma or pi?

A single bond is a sigma bond and any additional bonds after that connecting the same elements are pi bonds.
by RasikaObla_4I
Sun Nov 17, 2019 7:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Angles
Replies: 4
Views: 45

Re: VSEPR Angles

We should know the bond angles for the shapes that do not have lone pairs because the angles are constant. However, for the shapes with lone pairs, we need to know that the bond angles for trigonal pyramidal are less than 109.5 degrees.
by RasikaObla_4I
Sun Nov 17, 2019 6:43 pm
Forum: Electronegativity
Topic: Electron affinity
Replies: 2
Views: 131

Re: Electron affinity

Electronegativity is the ability of an atom to attract electrons to itself while electron affinity is the energy released when an electron is added to a neutral atom.
by RasikaObla_4I
Sun Nov 17, 2019 6:38 pm
Forum: Lewis Structures
Topic: Noble gases
Replies: 3
Views: 77

Re: Noble gases

Noble gases from the 3p orbital onwards are able to have an expanded octet because the electrons can expand into the d subshell. As a result, xenon is able to form a covalent bond because it can expand its octet.
by RasikaObla_4I
Sun Nov 17, 2019 6:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 5
Views: 80

Re: Lone Pairs

The ones we have gone over in lecture are bent, trigonal pyramidal, see-saw, and square planar.
by RasikaObla_4I
Sun Nov 17, 2019 6:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape of XeF4
Replies: 2
Views: 28

Re: Shape of XeF4

When you draw the lewis structure, you see that xenon has an expanded octet which means that there are six bonding regions including the two lone pairs on the xenon and the four bonding pairs to the fluoride. so the shape would be octahedral.
by RasikaObla_4I
Sun Nov 10, 2019 8:47 pm
Forum: Formal Charge and Oxidation Numbers
Topic: formal charge
Replies: 7
Views: 108

Re: formal charge

Usually, you only want to find formal charges if the question asks for it, but when drawing lewis structures with or without a charge, you want to calculate the formal charge of each atom and see if all the formal charges add up to the charge of the molecule.
by RasikaObla_4I
Sun Nov 10, 2019 7:21 pm
Forum: DeBroglie Equation
Topic: De Broglie Equation Derivation and Use
Replies: 7
Views: 258

Re: De Broglie Equation Derivation and Use

It is derived from the equations E=momentum * speed of light and E= hc/wavelength. Combining both of those, you get wavelength= h/momentum. You use the de Broglie equation for any particle with momentum and wavelength properties.
by RasikaObla_4I
Sun Nov 10, 2019 7:07 pm
Forum: Lewis Structures
Topic: expanded octet
Replies: 3
Views: 38

Re: expanded octet

The ones you probably need to know for this class would be sulfur, phosphorus, chlorine, and silicon because their electrons expand into the 3d orbital.
by RasikaObla_4I
Sun Nov 10, 2019 7:05 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization Energy
Replies: 5
Views: 230

Re: Ionization Energy

Ionization decreases down a group and increases across a period. The ionization energy decreases down a group because as the number of shells increases, the electrons are shielded from the nucleus, so it takes less energy to remove the last electron. The ionization energy increases across a period b...
by RasikaObla_4I
Sun Nov 10, 2019 6:59 pm
Forum: Octet Exceptions
Topic: electron number in octet
Replies: 8
Views: 205

Re: electron number in octet

Expanded octets usually occur for phosphorus, sulfur, chlorine, and silicon. The number of electrons that a molecule with an expanded octet usually depends on the total number of valence electrons present in the entire molecule and the overall charge of the molecule. An expanded octet usually occurs...
by RasikaObla_4I
Sun Nov 03, 2019 10:06 pm
Forum: Properties of Light
Topic: Solving for energy of a photon
Replies: 3
Views: 90

Re: Solving for energy of a photon

Yes, we did a problem like this in one of the review sessions, and we used the equation En=-hR/n^2 to solve for the change in energy.
by RasikaObla_4I
Sun Nov 03, 2019 9:59 pm
Forum: Trends in The Periodic Table
Topic: Ionization
Replies: 5
Views: 284

Re: Ionization

Oxygen has a lower ionization energy because when you add an electron, it is added to an already half full orbital while for nitrogen, only half the orbital is full. As a result, there is electron-electron repulsion which lowers the ionization energy for oxygen.
by RasikaObla_4I
Sun Nov 03, 2019 9:52 pm
Forum: Ionic & Covalent Bonds
Topic: Midterm
Replies: 2
Views: 35

Re: Midterm

Lavelle said in the lecture that only the information up to 2D exercises in the textbook will be covered.
by RasikaObla_4I
Sun Nov 03, 2019 9:51 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 3
Views: 44

Re: Formal Charge

You would only have to calculate it if it is specified, but you should calculate the formal charge of the structure to find out if the structure is in its most stable state.
by RasikaObla_4I
Sun Nov 03, 2019 9:49 pm
Forum: Photoelectric Effect
Topic: Threshold
Replies: 3
Views: 142

Re: Threshold

You will normally be given the threshold value, but it is not a constant value. Also, it is hvphoton= threshold +1/2mv^2.
by RasikaObla_4I
Sun Oct 27, 2019 9:02 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic VS. Covalent Bond
Replies: 8
Views: 120

Re: Ionic VS. Covalent Bond

Ionic bonds occur between a metal and a nonmetal and a covalent bond is between two nonmetals.
by RasikaObla_4I
Sun Oct 27, 2019 8:08 pm
Forum: Lewis Structures
Topic: Orbitals
Replies: 9
Views: 114

Re: Orbitals

Yes, I believe so because you remove electrons from the farthest orbital usually.
by RasikaObla_4I
Sun Oct 27, 2019 8:06 pm
Forum: Lewis Structures
Topic: Lone Pairs
Replies: 12
Views: 117

Re: Lone Pairs

You count the number of electrons that aren't shared in a bond between another molecule. For example in a C-O (single) bond, the oxygen has 3 lone pairs and Carbon has 3 lone pairs.
by RasikaObla_4I
Sun Oct 27, 2019 8:03 pm
Forum: Resonance Structures
Topic: Formal Charge
Replies: 5
Views: 79

Re: Formal Charge

No, I don't believe so because a formal charge is a charge assigned to an atom assuming that electrons are equally shared within a chemical bond.
by RasikaObla_4I
Sun Oct 27, 2019 7:55 pm
Forum: Lewis Structures
Topic: Choosing the central atom
Replies: 16
Views: 196

Choosing the central atom

Is there a rule for choosing the central atom? And are there some atoms that will always be the central atom?
by RasikaObla_4I
Sun Oct 20, 2019 11:10 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: spin
Replies: 3
Views: 46

Re: spin

According to the Pauli Exclusion Principle, if 2 electrons are in the same orbital, then the spin is paired which means they spin in the opposite direction. Usually the spin starts up.
by RasikaObla_4I
Sun Oct 20, 2019 10:55 pm
Forum: Quantum Numbers and The H-Atom
Topic: quantum numbers
Replies: 2
Views: 49

Re: quantum numbers

If you are given the value of one of the quantum numbers, you can figure out the specific value for the other quantum numbers. For example if you are given a value for n, you can find the possible values of l and ml.
by RasikaObla_4I
Sun Oct 20, 2019 10:47 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Stern and Gerlach Experiment: Electron Spin
Replies: 3
Views: 34

Re: Stern and Gerlach Experiment: Electron Spin

The Stern and Gerlach experiment revealed how electrons don't have the same spin which differed from the classical prediction. Since electrons can be spun up or down, we use a 4th quantum number, ms which is the spin magnetic number.
by RasikaObla_4I
Sun Oct 20, 2019 10:40 pm
Forum: Properties of Electrons
Topic: Mass of Proton, Electron and Neutron
Replies: 2
Views: 61

Re: Mass of Proton, Electron and Neutron

I believe the mass of the electron is given on the formula sheet. I don't think you will need to know the mass of a proton or a neutron, unless it is given in the problem.
by RasikaObla_4I
Sun Oct 20, 2019 6:44 pm
Forum: Properties of Light
Topic: Week 3 Homework
Replies: 9
Views: 166

Re: Week 3 Homework

I remember Lavelle telling us that the homework due for week 3 should only be on the quantum topics.
by RasikaObla_4I
Sun Oct 13, 2019 10:34 pm
Forum: DeBroglie Equation
Topic: DeBroglie Equation
Replies: 9
Views: 134

Re: DeBroglie Equation

The DeBroglie Equation is only used for any moving particles with momentum and has wavelike properties with wavelength. Light does not have any mass so it cannot be used to calculate momentum.
by RasikaObla_4I
Sun Oct 13, 2019 10:28 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: When to use the Bohr Frequency Condition?
Replies: 3
Views: 48

Re: When to use the Bohr Frequency Condition?

The Bohr Frequency Condition is used when a high energy electron drops to a lower energy level and the difference in energy is given off as a photon.
by RasikaObla_4I
Sun Oct 13, 2019 10:23 pm
Forum: Significant Figures
Topic: sig figs and periodic tables
Replies: 11
Views: 398

Re: sig figs and periodic tables

The periodic table given on the test was the one on his website, so I would use that one. I would also go to the last decimal place given on the periodic table and not round your final answer till the end.
by RasikaObla_4I
Sun Oct 13, 2019 10:20 pm
Forum: General Science Questions
Topic: Powerpoint Slides
Replies: 4
Views: 94

Re: Powerpoint Slides

I'm not sure if he posts power points of the slides, but I know he has modules for each of the quantum lessons on his website that you can take notes on.
by RasikaObla_4I
Sun Oct 13, 2019 10:17 pm
Forum: *Black Body Radiation
Topic: Black Body
Replies: 6
Views: 237

Re: Black Body

A black body is a physical body that absorbs all electromagnetic radiation regardless of frequency.
by RasikaObla_4I
Sun Oct 06, 2019 12:51 am
Forum: Molarity, Solutions, Dilutions
Topic: Which Volume to use for M1
Replies: 6
Views: 83

Re: Which Volume to use for M1

V1 is usually the initial volume that you use to create the second molarity, so if you are solving for V2, you use the smaller volume in the equation for M1.
by RasikaObla_4I
Sun Oct 06, 2019 12:45 am
Forum: Balancing Chemical Reactions
Topic: Strategies for Balancing Chemical Equations
Replies: 12
Views: 179

Re: Strategies for Balancing Chemical Equations

I balance the element that occurs the least in the equation. For example, if hydrogen occurs two times in the reaction and it is the least occurring element, I balance that first and then move on to the next element that occurs the least. If there's an odd number of moles of an element, you balance ...
by RasikaObla_4I
Sun Oct 06, 2019 12:33 am
Forum: Empirical & Molecular Formulas
Topic: Decimals to Whole Numbers
Replies: 6
Views: 272

Re: Decimals to Whole Numbers

usually you have a margin of error or plus or minus .1. it also depends on what you are using it for. FOr empirical/molecular you can round like 3.8 to 4 (from what I have been told)
by RasikaObla_4I
Sun Oct 06, 2019 12:29 am
Forum: Balancing Chemical Reactions
Topic: Strategies for Balancing Chemical Equations
Replies: 12
Views: 179

Re: Strategies for Balancing Chemical Equations

i start with the elements that are not carbon and then the rest before balancing hydrogen and oxygen
by RasikaObla_4I
Sun Oct 06, 2019 12:23 am
Forum: Empirical & Molecular Formulas
Topic: Chemical Formulas
Replies: 2
Views: 67

Re: Chemical Formulas

There is a formula sheet that will be given for the test, but on the safe side, you should memorize the list of polyatomic ions.
by RasikaObla_4I
Sun Oct 06, 2019 12:20 am
Forum: Empirical & Molecular Formulas
Topic: Limiting Reactants
Replies: 4
Views: 81

Re: Limiting Reactants

If the question asks for it, then you should subtract the grams of the amount of the excess reactant from the grams of the limiting reactant already calculated.

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