Search found 103 matches

by Ashley Nguyen 2L
Sun Mar 15, 2020 11:44 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Electrode size [ENDORSED]
Replies: 2
Views: 75

Re: Electrode size [ENDORSED]

The size of the electrode should not change the potential of the cell because it is solid and the reaction quotient does not take solids or liquids into consideration
by Ashley Nguyen 2L
Sun Mar 15, 2020 11:43 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Activation Energy
Replies: 4
Views: 56

Re: Activation Energy

Normally if the activation energy is higher, the reaction rate is slower because it requires more energy.
by Ashley Nguyen 2L
Sun Mar 15, 2020 11:42 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: ΔGionization
Replies: 8
Views: 174

Re: ΔGionization

I believe that deltaG ionization is calculated the same as normal standard gibbs free energy.
by Ashley Nguyen 2L
Sun Mar 15, 2020 11:40 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy Ionization
Replies: 2
Views: 66

Re: Gibbs Free Energy Ionization

I don't think so. I calculated Gibbs free energy ionization the same way as standard gibbs free energy.
by Ashley Nguyen 2L
Sun Mar 15, 2020 11:40 pm
Forum: Balancing Redox Reactions
Topic: Oxidation/Reduction
Replies: 17
Views: 219

Re: Oxidation/Reduction

You would consider one specific atom within a molecule
by Ashley Nguyen 2L
Sat Mar 14, 2020 7:04 pm
Forum: General Rate Laws
Topic: Rate Law
Replies: 2
Views: 96

Re: Rate Law

An integrated rate law gives the rate of reaction based on time, while a differential rate law gives the rate of reaction based on reactant concentration.
by Ashley Nguyen 2L
Sat Mar 14, 2020 7:02 pm
Forum: Balancing Redox Reactions
Topic: balancing h and o
Replies: 7
Views: 132

Re: balancing h and o

I usually balance the O first using H2O and then balance the H using H+ afterwards
by Ashley Nguyen 2L
Mon Mar 09, 2020 12:21 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cells
Replies: 3
Views: 54

Re: Concentration Cells

A concentration cell has the same anode and cathode, which means that electron transfer comes from differences in concentration. When the two electrodes are connected, electrons from the cell with the lower concentration (the anode) move to the cell with the higher concentration (cathode) to create ...
by Ashley Nguyen 2L
Mon Mar 09, 2020 12:17 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration
Replies: 9
Views: 68

Re: Concentration

If you are referring to a galvanic cell, you would use the Nernst Equation, which is Ecell = Enot - RT/nF lnQ, where Q = [products]/[reactants]. If you are given all other variables, you can solve for the concentration of the anode or cathode.
by Ashley Nguyen 2L
Mon Mar 09, 2020 12:16 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: E cell
Replies: 9
Views: 117

Re: E cell

E standard cell, which is sometimes called Enot, is the standard state cell potential at state conditions, which is 25C, 1 atm. Ecell is the cell potential at non standard state condition. This value can be found by using the Nernst Equation.
by Ashley Nguyen 2L
Mon Mar 09, 2020 12:14 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Anode concentration
Replies: 3
Views: 35

Re: Anode concentration

To find anode concentration, you should use the Nernst Equation, which is E = Enot - RT/nF lnQ, where Q = [products]/[reactants].
by Ashley Nguyen 2L
Mon Mar 09, 2020 12:11 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Concentration Cell
Replies: 5
Views: 71

Re: Concentration Cell

A concentration cell has the same compound as both anode and cathode. This makes the Enot equal to zero. This reaction is driven by the difference in concentrations of both the anode and cathode, with the anode being the side with the lower concentration
by Ashley Nguyen 2L
Sun Mar 01, 2020 10:33 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: electron flow
Replies: 4
Views: 31

Re: electron flow

The term voltage refers to the flow of electrons. If voltage is moving from left to right, then electrons is flowing from right to left. Because electricity refers to the presence and flow of electrons, they can be used interchangeably.
by Ashley Nguyen 2L
Sun Mar 01, 2020 10:30 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cell potential
Replies: 15
Views: 119

Re: cell potential

deltaG = -nFE, so if E is positive, deltaG would be negative, showing that the reaction is spontaneous. If E is negative, then deltaG is negative, showing that the reaction is not spontaneous.
by Ashley Nguyen 2L
Sun Mar 01, 2020 10:28 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: salt bridge
Replies: 9
Views: 82

Re: salt bridge

Some common salts used in a salt bridge are sodium chloride, potassium chloride, and potassium nitrate. The electrolyte chosen must easily dissociate and not react with any of the chemicals in the cell.
by Ashley Nguyen 2L
Sun Mar 01, 2020 10:25 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Test 2
Replies: 4
Views: 54

Re: Test 2

He will most likely give us a paper of the standard cell potentials.
by Ashley Nguyen 2L
Sun Mar 01, 2020 10:23 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagrams
Replies: 6
Views: 43

Re: Cell Diagrams

It shouldn't matter what order you write Fe2+ and Fe3+ in because they are in the same phase.
by Ashley Nguyen 2L
Sun Feb 23, 2020 4:58 pm
Forum: Balancing Redox Reactions
Topic: Oxidation number of H
Replies: 6
Views: 79

Re: Oxidation number of H

Generally, H has a charge of +1. This is true when it acts as a cation or when it is bound to a nonmetal. H will have a charge of -1 only when it is bonded to a cation/metal.
by Ashley Nguyen 2L
Sun Feb 23, 2020 4:55 pm
Forum: Balancing Redox Reactions
Topic: Figuring Out Electrons Transferred for a Problem Where Both Sides Have The Same Oxidation Number
Replies: 3
Views: 38

Re: Figuring Out Electrons Transferred for a Problem Where Both Sides Have The Same Oxidation Number

When solving the half reaction for O3 -> O2, both sides must be balanced by using H2O and H+. This would make the equation O3 + 2H+ -> O2 + H2O, but now the charges on each side are not balanced. So, you would add 2e- on the left side to make the charges of both sides equal to zero.
by Ashley Nguyen 2L
Sun Feb 23, 2020 4:52 pm
Forum: Balancing Redox Reactions
Topic: spontaneous
Replies: 15
Views: 142

Re: spontaneous

The standard reaction potential is positive when the reaction is spontaneous.
by Ashley Nguyen 2L
Sun Feb 23, 2020 4:51 pm
Forum: Balancing Redox Reactions
Topic: Adding H2O and OH- to Balance
Replies: 5
Views: 56

Re: Adding H2O and OH- to Balance

If you're using OH- to balance an equation, I'm going to assume the reaction is occurring under basic conditions. First, balance all elements except for hydrogen and oxygen. Then, add H2O to balance the oxygen on the opposing side. Then, balance the hydrogen by using H+, and then the charges by usin...
by Ashley Nguyen 2L
Sun Feb 23, 2020 4:44 pm
Forum: Balancing Redox Reactions
Topic: Basic and Acidic Conditions
Replies: 5
Views: 60

Re: Basic and Acidic Conditions

When balancing a reaction in an acidic solution, balance the equations by using H3O+ and H2O. If in a basic solution, balance by using OH- and H2O. Everything else will remain the same.
by Ashley Nguyen 2L
Sun Feb 16, 2020 5:19 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: q of ice and q of water
Replies: 8
Views: 136

Re: q of ice and q of water

If ice is placed in water, the system will attempt to equilibrate with heat flow from the water to the ice. Therefore, qWater = -qIce. This can also be derived from the fact that qWater + qIce = 0, since all heat is being exchanged between the 2 objects and nothing else.
by Ashley Nguyen 2L
Sun Feb 16, 2020 5:13 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs Irreversible
Replies: 13
Views: 244

Re: Reversible vs Irreversible

For irreversible reactions, pressure is held constant as temperature changes, while reversible reactions show the change in both temperature and pressure. For irreversible reactions, work = - PdeltaV. For reversible, work = - nRTln (V2/V1), which represents an integral. In addition, entropyTotal = 0...
by Ashley Nguyen 2L
Sun Feb 16, 2020 5:06 pm
Forum: Calculating Work of Expansion
Topic: work = 0
Replies: 14
Views: 234

Re: work = 0

Because work is equal to Pexternal*deltaV, in a vacuum there is no external pressure, making work = 0. The system is not doing work on the surroundings because the surroundings are not pushing back.
by Ashley Nguyen 2L
Sun Feb 16, 2020 5:04 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: delta h and constant temp and pressure
Replies: 4
Views: 118

Re: delta h and constant temp and pressure

DeltaH is simply q at constant temperature, so it is the same by default. At constant pressure, deltaH is for a phase change.
by Ashley Nguyen 2L
Sun Feb 16, 2020 5:01 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: isolated system
Replies: 7
Views: 166

Re: isolated system

Yes, an isolated system would have w = 0 and q = 0 because no work can be done on or by the system and no heat can be exchanged. This also means that deltaU would equal zero because interna energy = q + w.
by Ashley Nguyen 2L
Sun Feb 09, 2020 11:18 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Spontaneous vs Favorable
Replies: 8
Views: 85

Re: Spontaneous vs Favorable

Spontaneous and favorable refers to the same thing: the reaction will occur without external energy being added.
by Ashley Nguyen 2L
Sun Feb 09, 2020 11:17 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Delta U
Replies: 7
Views: 83

Re: Delta U

DeltaU = 0 when there is an isothermal expansion. Although work is used, and heat is consequently lost, heat flow from the surroundings replaces the heat lost, so temperature remains constant. If we know that deltaU = 0, and that deltaU = w + q, then q = -w. We can confirm that w is a negative value...
by Ashley Nguyen 2L
Sun Feb 09, 2020 11:12 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: m and n in heat capacity
Replies: 4
Views: 35

Re: m and n in heat capacity

Mass and moles in a problem usually refers to the same amount of a chemical because the two values can be converted into each other. When using mass, you calculate using the specific heat capacity, which gives joules per gram degree Celsius. When using moles, you calculate using molar heat capacity,...
by Ashley Nguyen 2L
Sun Feb 09, 2020 11:05 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: mCdeltaT
Replies: 3
Views: 33

Re: mCdeltaT

q = mCdeltaT should be used when temperature is changing. The delta shows that we take the final and initial temperatures into consideration, and all other variables are constant. When changing from one phase to another, the temperature does not change - just the phase. The q for the phase change ca...
by Ashley Nguyen 2L
Sun Feb 09, 2020 11:02 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: work on the system or by the system
Replies: 4
Views: 33

Re: work on the system or by the system

If work is done by the system, then w should be positive (system is gaining heat). If work is done on the system, then w should be negative (system is losing heat).
by Ashley Nguyen 2L
Sun Feb 02, 2020 10:58 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: work
Replies: 3
Views: 57

Re: work

Remember the equation used to calculate work: w = -P (deltaV). If volume were to decrease, then work would be positive, meaning that the surroundings did work on the system. If the volume increased, then work would be positive, meaning the system did work on the surroundings. The example Lavelle use...
by Ashley Nguyen 2L
Sun Feb 02, 2020 10:49 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: State Property
Replies: 5
Views: 49

Re: State Property

A state property is a value that does not depend on the path you take to get to a state, as long as you get to the final state. Enthalpy is a state property because this value only cares about the final and initial properties.
by Ashley Nguyen 2L
Sun Feb 02, 2020 10:45 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 4
Views: 43

Re: Hess's Law

I usually solve these problems by first lining up all the reactions so unnecessary reactants and products cancel out, flipping equations and multiplying by a coefficient when necessary. Keep in mind which equations you flip and change so you can also flip the sign or multiply the delta H. Then, you ...
by Ashley Nguyen 2L
Sun Feb 02, 2020 10:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: q vs H
Replies: 9
Views: 59

Re: q vs H

Heat transfer refers to q
by Ashley Nguyen 2L
Sun Feb 02, 2020 10:36 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond enthalpy calculations
Replies: 4
Views: 36

Re: Bond enthalpy calculations

At least for me, I think the best way to do these problems is to draw the lewis structures to figure out which bonds are formed and broken in the duration of the reaction
by Ashley Nguyen 2L
Sun Jan 26, 2020 11:35 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: 6C.13
Replies: 3
Views: 56

Re: 6C.13

Stronger bases form weaker conjugate acids. Higher pKa shows weaker conjugate acids because pKa is the negative log of Ka, which shows how much an acid would dissociate. To rank the compounds from weakest to strongest base, rank them in order of increasing pKa.
by Ashley Nguyen 2L
Sun Jan 26, 2020 11:33 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE BOX
Replies: 27
Views: 244

Re: ICE BOX

If the x is < 10^-3, then you can assume that the x has no effect on the denominator.
by Ashley Nguyen 2L
Sun Jan 26, 2020 11:29 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure & temperature in chemical equilibria
Replies: 3
Views: 29

Re: Pressure & temperature in chemical equilibria

When pressure increases, the reaction shift towards the side with less gas moles, and when pressure decreases, the reaction shifts towards the side with more gas moles. Shifts in temperatures depend if the chemical reaction is exothermic or endothermic. If endothermic and temperature increases, then...
by Ashley Nguyen 2L
Sun Jan 26, 2020 11:23 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Finding Ka from pH
Replies: 5
Views: 56

Re: Finding Ka from pH

You know that [H3O+] = 10^-pH and [OH-] = 10^-pOH. You can get the Ka or Kb values from using the [H3O+] and [OH-] respectively.
by Ashley Nguyen 2L
Sun Jan 26, 2020 11:22 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Negative Square Root solving an ICE box
Replies: 13
Views: 94

Re: Negative Square Root solving an ICE box

You should not receive a negative square root. You most likely did something wrong in the math and should check your work
by Ashley Nguyen 2L
Sun Jan 19, 2020 9:33 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pa and Pb
Replies: 4
Views: 45

Re: Pa and Pb

Pa is for acids and Pb is for bases. Depending on if you are solving for pH or pOH, use Pa to find pH and Pb to find pOH.
by Ashley Nguyen 2L
Sun Jan 19, 2020 9:29 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE Tables
Replies: 13
Views: 94

Re: ICE Tables

H2O is usually not included in its liquid form because it has a concentration of 1 at all times.
by Ashley Nguyen 2L
Sun Jan 19, 2020 9:28 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: exothermic/endothermic rxns
Replies: 4
Views: 41

Re: exothermic/endothermic rxns

In an endothermic or exothermic reaction, you can treat heat as a reactant or product depending on the reaction. In an endothermic reaction, heat is required, so heat would be considered a reactant. In an exothermic reaction, heat is released, so it would be considered a product. If you were to incr...
by Ashley Nguyen 2L
Sun Jan 19, 2020 9:25 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: H20 in the ICE table
Replies: 26
Views: 236

Re: H20 in the ICE table

When doing an ICE table, do not include water, liquids, or solids, as these do not have concentrations.
by Ashley Nguyen 2L
Sun Jan 19, 2020 9:24 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exo/Endo-thermic Rxns
Replies: 5
Views: 133

Re: Exo/Endo-thermic Rxns

If the reaction is endothermic (requires heat), pretend like heat is a reactant in the equation. [ A + B + heat -> C ] From here, you can treat an increase/decrease in temperature as an increase/decrease in reactant. If temperature increases in an endothermic reaction, then the reaction will shift r...
by Ashley Nguyen 2L
Sun Jan 12, 2020 11:37 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: solids and liquids
Replies: 5
Views: 42

Re: solids and liquids

Solids and liquids are not included in the K calculation because K is calculated using concentrations. Solids and liquids do not have concentrations, so they cannot affect the equilibrium.
by Ashley Nguyen 2L
Sun Jan 12, 2020 11:35 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K's
Replies: 3
Views: 39

Re: K's

Kc is the equilibrium constant using concentrations, while Kp is the equilibrium constant using partial pressures. Both are calculated the same way.
by Ashley Nguyen 2L
Sun Jan 12, 2020 11:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5G.9
Replies: 3
Views: 60

Re: 5G.9

D and E will remain the same. Both are equation used to find K of the reaction in the forward and reverse direction. This ratio is a fixed constant.
by Ashley Nguyen 2L
Sun Jan 12, 2020 11:32 pm
Forum: Ideal Gases
Topic: ICE Table
Replies: 9
Views: 100

Re: ICE Table

Change in molar concentration is usually positive on the product side because product are being created from the reactants. This means that the reactants must have a negative change in concentration.
by Ashley Nguyen 2L
Sun Jan 12, 2020 11:30 pm
Forum: Ideal Gases
Topic: K and Units
Replies: 7
Views: 42

Re: K and Units

K does not have any units because it is calculated using an approximation of a compound's chemical activity, which is unit-less.
by Ashley Nguyen 2L
Sat Dec 07, 2019 9:08 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 17.35 Chelating Compounds
Replies: 5
Views: 598

Re: 17.35 Chelating Compounds

How do you determine at what point the nitrogens are too far away to bond to the same metal atom? I think it's more of a common sense thing. If the nitrogens are on complete opposite sides of the benzene ring, it would be impossible for them to bond to the same metal atom. The ideal distance is nit...
by Ashley Nguyen 2L
Sat Dec 07, 2019 9:06 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: chelating ligands [ENDORSED]
Replies: 21
Views: 6231

Re: chelating ligands [ENDORSED]

Does anyone know what Dr. Lavelle means when he says: atom with lone pair --- spacer atom --- spacer atom --- atom with lone pair The only part i dont understand is spacer atom. What does spacer atom mean? Conceptually I see why C is the correct answer i am just unfamiliar with this terminology Spa...
by Ashley Nguyen 2L
Wed Nov 27, 2019 11:41 am
Forum: Naming
Topic: Naming Coordination Compound with Iron
Replies: 4
Views: 66

Re: Naming Coordination Compound with Iron

Iron is called ferrate because it is derived from its latin name ferrum. Because the periodic table refers to iron by its latin name (Fe), then we also take the latin root while naming.
by Ashley Nguyen 2L
Wed Nov 27, 2019 11:37 am
Forum: Naming
Topic: polydentate?
Replies: 7
Views: 91

Re: polydentate?

polydentate refers to the bonding of a ligand to more than one binding site of a central ion. This usually refers to lone pair donating sites on the central atom.
by Ashley Nguyen 2L
Wed Nov 27, 2019 11:36 am
Forum: Naming
Topic: 9C.1
Replies: 6
Views: 111

Re: 9C.1

a. hexacyanoferrate (II) - there are 6 cyanide groups, and 1 iron atom; iron becomes ferrate, and because the overall charge of the coordination compound is negative, it receives the -ate suffix. You can tell the iron has a +2 charge because each cyanide has a -1 charge (x6) and the overall charge i...
by Ashley Nguyen 2L
Wed Nov 27, 2019 11:29 am
Forum: Naming
Topic: Naming Convention of Metal Anions
Replies: 5
Views: 58

Re: Naming Convention of Metal Anions

The metal anion receives the -ate suffix when the coordination compound is negative overall
by Ashley Nguyen 2L
Wed Nov 27, 2019 11:27 am
Forum: Naming
Topic: Self-test 9C.1B
Replies: 2
Views: 43

Re: Self-test 9C.1B

a. The name should be pentamminebromidocobalt (III) sulfate. This is because there are 5 ammonia groups, 1 bromide atom, 1 cobalt with a +3 charge, and a sulfate.
b. The formula is [Cr(NH3)4(OH2)2] Br3
by Ashley Nguyen 2L
Wed Nov 20, 2019 4:01 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Is ICl2- Polar or Non-polar?
Replies: 2
Views: 47

Re: Is ICl2- Polar or Non-polar?

ICl2- would be nonpolar because dipoles are created only from bonded electrons. The 3 lone pairs do not have a strong enough force to create a dipole in this molecule.
by Ashley Nguyen 2L
Wed Nov 20, 2019 3:59 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Big Molecule
Replies: 2
Views: 34

Re: Big Molecule

I believe the best way would be to treat this molecule as a hydrocarbon chain with the nitrogen on the end. The nitrogen will most likely be double bonded to the end carbon, but be sure to check how many electrons the molecule should have and formal charges.
by Ashley Nguyen 2L
Wed Nov 20, 2019 3:57 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Can linear molecular shapes have lone pair?
Replies: 4
Views: 57

Re: Can linear molecular shapes have lone pair?

Many atoms with multiple electron density regions can create linear molecules with the right number of lone pairs. AX2, AX2E2, AX2E3, and AX2E4 are all linear with lone pairs.
by Ashley Nguyen 2L
Wed Nov 20, 2019 3:53 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Ionic Bonds
Replies: 4
Views: 44

Re: Ionic Bonds

Ionic bonds are normally formed between any metal and any nonmetal because of their difference in electronegativity, which allows one atom, the anion/metal, to "take" electrons away from the cation/nonmetal. Metals include both the alkali and alkali-earth metals, as well as some transition...
by Ashley Nguyen 2L
Wed Nov 20, 2019 3:50 am
Forum: Determining Molecular Shape (VSEPR)
Topic: N2O Lewis Structure/Pi and Sigma Bonds
Replies: 2
Views: 51

Re: N2O Lewis Structure/Pi and Sigma Bonds

N is the central atom because it is the least electronegative and because if formal charges are calculated, placing N as the central atom allows each atom to have the lowest FC. There are two sigma bonds and two pi bonds. The N-O single bond is a single sigma bond, while triple bond between N and N ...
by Ashley Nguyen 2L
Wed Nov 13, 2019 2:05 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: 3F19.c.
Replies: 2
Views: 46

Re: 3F19.c.

Although both molecules are composed of the same atoms, they have different structures which impacts the types of bonds they make. Both molecules create induced dipole-induced dipole bonds, but the strength of these forces differ because of the size of the molecules. Pentane is a smaller molecule so...
by Ashley Nguyen 2L
Wed Nov 13, 2019 1:55 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: 3F.5 (b)
Replies: 4
Views: 50

Re: 3F.5 (b)

Butanol has the strongest intermolecular bonds because of the -OH group that allows it to create hydrogen bonds between molecules. Diethyl ether has no OH group nor any strong partial positives/partial negatives, so the strongest bond it can make is a london dispersion force, which is the weakest of...
by Ashley Nguyen 2L
Wed Nov 13, 2019 1:51 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: 3F13
Replies: 6
Views: 194

Re: 3F13

For this problem, the choice showing dipole-dipole interactions between the molecules has the strongest attraction. In choice II, the partial positive H are nearest to the partial negative Cl, giving these molecules the strongest intermolecular interaction. In addition, you know that different molec...
by Ashley Nguyen 2L
Wed Nov 13, 2019 1:47 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: melting points
Replies: 5
Views: 43

Re: melting points

NaCl's ionic bonding is much stronger than the covalent bonds holding HCl together. Because the bond is stronger, more energy is needed to break the bond, resulting in a higher melting point.
by Ashley Nguyen 2L
Wed Nov 13, 2019 1:45 am
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: 3F3 HW Help
Replies: 1
Views: 27

Re: 3F3 HW Help

Dipole-dipole interactions are different than london dispersion forces. Dipole-dipole interactions occur between the partially positive charged atoms of one molecule and the partially negative charged atoms of another molecule. These partial positives occurs as a result of differences in electronega...
by Ashley Nguyen 2L
Sun Nov 10, 2019 10:34 pm
Forum: Lewis Structures
Topic: Lewis Dot Structures
Replies: 7
Views: 90

Re: Lewis Dot Structures

Because we have not discussed shape yet, which depends heavily on electron placement, it does not matter which side the lone electron goes on.
by Ashley Nguyen 2L
Sun Nov 10, 2019 10:32 pm
Forum: Dipole Moments
Topic: dipole moments
Replies: 2
Views: 37

Re: dipole moments

Dipole moments have many names, which include van der waals forces and london dispersion forces. Basically, the electron cloud around an atom can be influenced by the temporary positive attraction of another atom it is not bonded to. This temporary interaction creates a weak intermolecular bond betw...
by Ashley Nguyen 2L
Sun Nov 10, 2019 10:24 pm
Forum: Formal Charge and Oxidation Numbers
Topic: formal charge
Replies: 7
Views: 108

Re: formal charge

Formal charge is really mostly used to find the most stable resonance structure, so I would calculate it if a molecule has more than just single bonds
by Ashley Nguyen 2L
Tue Nov 05, 2019 11:51 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Midterm
Replies: 3
Views: 181

Re: Midterm

No, that will not be on the midterm
by Ashley Nguyen 2L
Tue Nov 05, 2019 11:32 pm
Forum: Properties of Light
Topic: Rydberg Equation
Replies: 5
Views: 221

Re: Rydberg Equation

I think we should just know the portion of the EM spectrum it corresponds to. I don't think there will be any in-depth questions on it
by Ashley Nguyen 2L
Wed Oct 30, 2019 3:10 am
Forum: Trends in The Periodic Table
Topic: Noble Gas
Replies: 4
Views: 63

Re: Noble Gas

The noble gases are included in all trends except electronegativity and electron affinity. This is because noble gases have a full valence shell of electrons, which means that they are in their most stable state. Because of this, they would not attempt to attract any electrons from another source, r...
by Ashley Nguyen 2L
Wed Oct 30, 2019 3:07 am
Forum: Trends in The Periodic Table
Topic: Ionization Energy
Replies: 5
Views: 63

Re: Ionization Energy

Ionization increases as you go up and to the right because, as you move to the right, the atoms have more protons in their nucleus, which exhibit a greater nuclear charge. This stronger positive charge attracts electrons more heavily, which makes it difficult for an electron to be pulled away. The e...
by Ashley Nguyen 2L
Wed Oct 30, 2019 3:04 am
Forum: Trends in The Periodic Table
Topic: Ionization Energy
Replies: 4
Views: 57

Re: Ionization Energy

The best way to tell which atom has the lowest ionization energy is by memorizing the periodic trends. Ionization energy increases as you go up and to the right. This is because ionization energy is defined as the amount of energy needed to remove an electron. As you move towards the right side of t...
by Ashley Nguyen 2L
Wed Oct 30, 2019 2:59 am
Forum: Trends in The Periodic Table
Topic: Summary of Periodic Trends [ENDORSED]
Replies: 2
Views: 48

Re: Summary of Periodic Trends [ENDORSED]

I'm not sure which ones we'd need to memorize for sure, but it's best to remember atomic radius, electron affinity, ionization energy, and electronegativity. Atomic radius increases towards the bottom left. Electron affinity increases towards the top right. Ionization energy and electronegativity in...
by Ashley Nguyen 2L
Wed Oct 30, 2019 2:41 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Question 1E 1
Replies: 3
Views: 71

Question 1E 1

Question 1E-1 states: w hich of the following increase when an electron in a lithium atom undergoes a transition from the 1s-orbital to a 2p-orbital? (a) Energy of the electron. (b) Value of n. (c) Value of l. (d) Radius of the atom. Which answers would be different for a hydrogen atom and in what w...
by Ashley Nguyen 2L
Wed Oct 23, 2019 1:34 am
Forum: Trends in The Periodic Table
Topic: Ionic Radius
Replies: 4
Views: 62

Re: Ionic Radius

For ground state atoms, the ionic radii changes from bigger to smaller across a period because as the number of protons increases, the effective nuclear charge also increases, which pulls the electrons closer to the nucleus. However, anions follow a different pattern because they are bigger than the...
by Ashley Nguyen 2L
Wed Oct 23, 2019 1:28 am
Forum: Quantum Numbers and The H-Atom
Topic: 1D.13
Replies: 3
Views: 72

Re: 1D.13

You know that a d subshell corresponds to l = 2, and the ml is given by -l to l. Therefore, there are 5 values of ml: -2, -1, 0, 1, 2. You can also use the equation ml = 2l + 1 to find the value of ml.
by Ashley Nguyen 2L
Wed Oct 23, 2019 1:26 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Energy of Electrons
Replies: 6
Views: 75

Re: Energy of Electrons

The energy of an electron increases when it moves up an energy level. This is because energy, in the form of a photon, can excite an electron to a higher state. Conversely, when an electron moves down an energy level, it loses energy.
by Ashley Nguyen 2L
Wed Oct 23, 2019 1:22 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Subshell vs. Orbital
Replies: 9
Views: 160

Re: Subshell vs. Orbital

Shells are divided into subshells, which are further divided into orbitals. The principle quantum number n gives the shell, while the angular momentum number l gives the subshell. The last main quantum number, ml, which is the magnetic quantum number, gives the orbital of the electron.
by Ashley Nguyen 2L
Wed Oct 23, 2019 1:17 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 1 B27
Replies: 5
Views: 255

Re: 1 B27

On this problem, you are given the mass and uncertainty in velocity. You can use these numbers to solve for the uncertainty in momentum using the equation p = mv. You can then use this calculated value of p in the Heisenberg Uncertainty Principle, which is defined as deltaP*deltaX >= h / (4pi). Rear...
by Ashley Nguyen 2L
Wed Oct 16, 2019 3:31 am
Forum: Properties of Electrons
Topic: Intensity vs. Energy
Replies: 10
Views: 124

Re: Intensity vs. Energy

In the photoelectric experiment, light was acting as a particle known as a photon. Increasing the intensity of the light changed only the number of photons being used and nothing else. This is why increasing intensity did not affect the electrons being emitted. A single photon must have enough energ...
by Ashley Nguyen 2L
Wed Oct 16, 2019 3:28 am
Forum: Properties of Electrons
Topic: 1B.5
Replies: 2
Views: 44

Re: 1B.5

An eV is an electron volt, so a keV is a kilo-electron volt. To convert this unit to Joules, first multiply by 1000 eV/1keV to get the number in normal eV units. Use the conversion factor 1 eV = 1.602 x 10^-19J to get joules. Once you have joules, use the equation E = (hc)/(wavelength) to receive wa...
by Ashley Nguyen 2L
Wed Oct 16, 2019 3:23 am
Forum: Properties of Light
Topic: Relationships
Replies: 2
Views: 41

Re: Relationships

Yup, you're right. In the equation c= (frequency)(wavelength), frequency and wavelength are inversely proportional because their product is a constant, the speed of light. If frequency were to increase, then wavelength would have to decrease. In the next equation E = hv, energy is equal to frequency...
by Ashley Nguyen 2L
Wed Oct 16, 2019 3:20 am
Forum: Properties of Light
Topic: Question 1A.5
Replies: 4
Views: 71

Re: Question 1A.5

Yup, that would mean the least to greatest amount of energy. In terms of wavelengths and frequencies, the photons with the least amount of energy would have the longest wavelengths/lowest frequency. The photons with the greatest amount of energy would have the shortest wavelength/highest frequency b...
by Ashley Nguyen 2L
Wed Oct 16, 2019 3:16 am
Forum: Properties of Light
Topic: Electromagnetic Radiation
Replies: 3
Views: 41

Re: Electromagnetic Radiation

Following the EM spectrum, the photons would be ordered microwaves, visible light, ultraviolet radiation, x-rays, gamma rays from lowest to highest energy. This is because microwaves has the lowest frequency/longest wavelengths, which corresponds to lower energy. The higher the frequency/shorter the...
by Ashley Nguyen 2L
Wed Oct 16, 2019 3:13 am
Forum: Properties of Light
Topic: 1A.11
Replies: 2
Views: 39

Re: 1A.11

The Balmer and Lyman series are grouped the way they are because of how they were discovered. The Balmer series corresponds to the emission lines emitted when a hydrogen atom returns to the energy level with principle quantum number 2. The Lyman series corresponds to the lower energy level with prin...
by Ashley Nguyen 2L
Mon Oct 14, 2019 12:21 pm
Forum: Properties of Electrons
Topic: Calculating amount of energy needed to remove an electron
Replies: 1
Views: 49

Calculating amount of energy needed to remove an electron

How much energy is required to remove an electron from one sodium atom, given that light hits a sodium metal surface and the velocity of the ejected electron is 6.61 x 105 m.s-1. The work function for sodium is 150.6 kJ.mol-1. Would I just use the conversion 1 mol = 6.02x10^23 atoms to convert the w...
by Ashley Nguyen 2L
Wed Oct 09, 2019 2:02 am
Forum: Empirical & Molecular Formulas
Topic: Molecular formula
Replies: 6
Views: 697

Re: Molecular formula

If you were given the total molecular mass and the mass percentage composition of each element, you can assume that you have 100. g of the substance and convert each percentage to its respective mass (ie converting 45.6% carbon to 45.6 g of carbon). Next, you would find the moles of each element by ...
by Ashley Nguyen 2L
Wed Oct 09, 2019 1:55 am
Forum: Properties of Light
Topic: Light and our Skin
Replies: 2
Views: 62

Re: Light and our Skin

I don't believe UV radiation is harmful to our skin because of its potential to eject electrons. Because our skin is not made of metal and we are not in a vacuum, the concept of the photoelectric effect does not apply to our skin. UV radiation is harmful to us because the rays have enough energy to ...
by Ashley Nguyen 2L
Wed Oct 09, 2019 1:50 am
Forum: Properties of Light
Topic: Hw Question 1A.9
Replies: 5
Views: 78

Re: Hw Question 1A.9

To find the wavelength and frequency of the photon in this question, it is best to start from what you know. You know the energy of the photon, so the only equation we can use in this instance would be E(photon) = vh, where v is the frequency in Hertz and h is Planck's constant. Rearrange the equati...
by Ashley Nguyen 2L
Wed Oct 09, 2019 1:43 am
Forum: Properties of Light
Topic: Question 1A.5
Replies: 3
Views: 72

Re: Question 1A.5

You are correct. Shorter wavelength/higher frequency corresponds to higher energy, while longer wavelength/lower frequency corresponds to lower energy. This is because a particle is able to complete more oscillations in a 1 second interval.
by Ashley Nguyen 2L
Wed Oct 09, 2019 1:35 am
Forum: Properties of Light
Topic: Light intensity
Replies: 6
Views: 96

Re: Light intensity

If light is at a higher intensity, the amplitude of the wave is simply higher. The frequency and wavelength remains the same. One way you could achieve a higher intensity light is by increasing the number of photons. However, this change did not impact the photoelectric experiment because one single...
by Ashley Nguyen 2L
Wed Oct 09, 2019 1:32 am
Forum: Properties of Light
Topic: Question 1A.3 c
Replies: 5
Views: 126

Re: Question 1A.3 c

According to the equation c = λv, where c is a constant representing the speed of light in a vacuum, λ (wavelength) and v (frequency) are indirectly proportional. If frequency were to increase, wavelength must decrease. In this question, the frequency decreases, so wavelength must therefore increase...
by Ashley Nguyen 2L
Tue Oct 01, 2019 1:09 pm
Forum: Empirical & Molecular Formulas
Topic: Homework Problem E.9c
Replies: 5
Views: 88

Re: Homework Problem E.9c

How do you find the formula for magnesium sulfate heptahydrate? To find the formula for magnesium sulfate hydrate, you must know the ions that magnesium and sulfate form. Magnesium always forms Mg2+ and sulfate is (SO4)2-. Therefore, magnesium sulfate is MgSO4. Hepta- is a prefix meaning 7, so ther...
by Ashley Nguyen 2L
Tue Oct 01, 2019 1:05 pm
Forum: Empirical & Molecular Formulas
Topic: Percentage Yield
Replies: 3
Views: 54

Re: Homework Problem M.1

The percentage yield is the actual yield, which is the 25.2g of hydrazine, divided by the theoretical yield, which is the maximum product that can be produced, then multiplied by 100 to obtain a percent. To find the theoretical yield, you would need to convert the grams of reactant, ammonia, to mole...
by Ashley Nguyen 2L
Tue Oct 01, 2019 12:58 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding [ENDORSED]
Replies: 12
Views: 284

Re: Rounding [ENDORSED]

Rounding in chemistry usually occurs at the very end of your calculations in order to prevent rounding differences from accumulating.

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