Search found 86 matches

by Charysa Santos 4G
Sun Feb 16, 2020 3:41 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Delta S
Replies: 7
Views: 25

Re: Delta S

Delta S of the system is the entropy of the system, Delta S of the surroundings is the entropy of the surroundings (usually just the opposite/negative of Delta S), and the Delta S (total) is 0 for isothermal reversible reactions and is usually equal to Delta S (sys) for irreversible reactions.
by Charysa Santos 4G
Sun Feb 16, 2020 3:37 pm
Forum: Phase Changes & Related Calculations
Topic: Heating curve
Replies: 5
Views: 32

Re: Heating curve

Phase changes correlate to the plateau of a heating curve, and there, you can use q = mΔh if you are given mass or q = nΔh if you are given moles. If you are calculating the diagonal/rise in temperature, you will use q = mCΔT or q = nCΔT.
by Charysa Santos 4G
Sun Feb 16, 2020 3:16 pm
Forum: Ideal Gases
Topic: pv=nrt
Replies: 13
Views: 39

Re: pv=nrt

PV = nRT can be used at STP if you plug in 273.15 Kelvin for the temperature (T) and 1 atm for pressure (P)
by Charysa Santos 4G
Sun Feb 16, 2020 3:10 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Why are exothermic reactions generally spontaneous?
Replies: 15
Views: 72

Re: Why are exothermic reactions generally spontaneous?

Exothermic reactions are generally spontaneous, because unlike endothermic reactions, they do not require heat input
by Charysa Santos 4G
Sun Feb 16, 2020 2:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: endo/exo and temp
Replies: 8
Views: 26

Re: endo/exo and temp

Think of energy/heat being a reactant in endothermic reactions (heat must be supplied), and as a product in exothermic reactions (heat is being released). So when you increase temperature in an endothermic reaction, you are increasing the amount of reactants so the reaction will favor the products, ...
by Charysa Santos 4G
Sun Feb 09, 2020 8:35 pm
Forum: Ideal Gases
Topic: reversing reactions
Replies: 9
Views: 27

Re: reversing reactions

The K of a reverse reaction is just the inverse of K (or 1/K)
by Charysa Santos 4G
Sun Feb 09, 2020 8:33 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: spontaneity
Replies: 18
Views: 36

Re: spontaneity

You can tell that a reaction is spontaneous when Gibbs free energy (delta G) is negative, which means that it is releasing free energy.
by Charysa Santos 4G
Sun Feb 09, 2020 8:29 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Enthalpy versus heat
Replies: 11
Views: 41

Re: Enthalpy versus heat

Delta H is equal to q + w, so when there is no work being done on or by the system (or when w = 0), then delta H = q
by Charysa Santos 4G
Sun Feb 09, 2020 8:27 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: difference between molar entropies?
Replies: 6
Views: 16

Re: difference between molar entropies?

For each mole of lead, there are more protons, electrons, and neutrons than in carbon, so on a sub-atomic level, there is more entropy because these particles' movements contribute to the atom's overall entropy.
by Charysa Santos 4G
Sun Feb 09, 2020 8:24 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies
Replies: 6
Views: 17

Re: Bond Enthalpies

Bond enthalpy questions usually give you the reaction (A + B --> C) and then you just look at each molecule that is in the reaction and look up their bond enthalpy values. Bonds broken are usually correlated to those of the reactants and bonds formed correlate to those of the products.
by Charysa Santos 4G
Sun Feb 02, 2020 8:31 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Positive or negative work?
Replies: 8
Views: 29

Re: Positive or negative work?

Positive work = the surroundings are doing work on the system (i.e. positive delta H when heat (energy) is being added to a system)
Negative work = the system is doing work to its surroundings (i.e. negative delta H when heat (energy) is leaving a system)
by Charysa Santos 4G
Sun Feb 02, 2020 8:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1 #6
Replies: 6
Views: 34

Re: Test 1 #6

HF is not a strong acid, therefore it does not completely ionize (100%)
by Charysa Santos 4G
Sun Feb 02, 2020 8:25 pm
Forum: Ideal Gases
Topic: PV=nRT
Replies: 10
Views: 27

Re: PV=nRT

P = Pressure, V = Volume, n = number of moles, R = gas constant, and T = Temperature
by Charysa Santos 4G
Sun Feb 02, 2020 8:24 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Temperature
Replies: 14
Views: 36

Re: Temperature

A negative delta H is exothermic because that means that energy is leaving (-) the system.
by Charysa Santos 4G
Sun Feb 02, 2020 8:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1
Replies: 6
Views: 24

Re: Test 1

If Q is less than K, that means that the ratio of products to reactants is lower than at equilibrium, so the reaction will favor the products. If the Q is greater than K, then the ratio of products to reactants is higher than at equilibrium, so the reaction will favor the reactants.
by Charysa Santos 4G
Sun Jan 26, 2020 10:07 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Gas Constant
Replies: 13
Views: 29

Re: Gas Constant

The gas constant (R) depends on what other units are given to you when calculating PV = nRT. The units are included on the formula/equation sheet.
by Charysa Santos 4G
Sun Jan 26, 2020 10:03 pm
Forum: Ideal Gases
Topic: Determining N
Replies: 9
Views: 34

Re: Determining N

PV = nRT is the Ideal Gas Constant, so it applies to gases, not aqueous solutions.
by Charysa Santos 4G
Sun Jan 26, 2020 10:02 pm
Forum: Ideal Gases
Topic: R Constant
Replies: 18
Views: 70

Re: R Constant

The R depends on what other units you are working with in your PV = nRT calculation.
by Charysa Santos 4G
Sun Jan 26, 2020 10:01 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE BOX
Replies: 27
Views: 72

Re: ICE BOX

If your K is less than 10^-3, you can approximate the denominator.
by Charysa Santos 4G
Sun Jan 26, 2020 10:00 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: pH
Replies: 7
Views: 34

Re: pH

If they give you the pKa, they would likely also have given the concentration of either [OH-] or [H3O+] or you would have to solve for them, and then you could use that value to do -log([H3O+]/[OH-]) and find the pH/pOH.
by Charysa Santos 4G
Sun Jan 19, 2020 7:20 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: X was ignored
Replies: 27
Views: 80

Re: X was ignored

If the given K is less than 10^-3, then you can use approximation, meaning that you can disregard the X because it is small enough that it would not profoundly impact your equilibrium expression.
by Charysa Santos 4G
Sun Jan 19, 2020 7:18 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pH and pOH
Replies: 5
Views: 7

Re: pH and pOH

If you know the pH, for example pH = 6, then according to the equation pH + pOH = 14 (derived from pKw = pH + pOH) then you would just set pOH = 14 - pH (6) so your pOH would equal 8.
by Charysa Santos 4G
Sun Jan 19, 2020 7:16 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Approximation
Replies: 6
Views: 22

Re: Approximation

It's just a general rule to check whether or not your approximation is valid because the amount (X) should be small enough that it wouldn't profoundly impact your equilibrium expression.
by Charysa Santos 4G
Sun Jan 19, 2020 7:09 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5% rule
Replies: 10
Views: 40

Re: 5% rule

The 5% rule is for checking whether or not your approximation is valid. This is usually if the K is less than 10^-3 and you take out the X from the denominator of your equilibrium expression.
by Charysa Santos 4G
Sun Jan 19, 2020 7:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: ice boc
Replies: 7
Views: 22

Re: ice boc

You can only take out the X in the denominator if the K is less than 10^-3. The ice box helps to visualize and take inventory of what you start with and what is changing at the equilibrium.
by Charysa Santos 4G
Fri Jan 10, 2020 12:41 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K for Heterogeneous Equilibria
Replies: 4
Views: 18

Re: K for Heterogeneous Equilibria

Kp is more particular to gases, and Kc applies to when concentrations are being used, so it would probably be safer to use Kc or just to leave K as is. I’m not completely sure, though...
by Charysa Santos 4G
Fri Jan 10, 2020 12:36 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: using Kp vs Kc
Replies: 13
Views: 34

Re: using Kp vs Kc

*Kc can be used for when concentrations are being used, while Kp is more particular to partial pressures and is more specific to gases.
by Charysa Santos 4G
Fri Jan 10, 2020 12:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: using Kp vs Kc
Replies: 13
Views: 34

Re: using Kp vs Kc

If all of the reactants and products are in the gas phase, then you must use Kp if only the partial pressures are given. Kc* is used for concentrations, and is thus used when the reactants and products are in the aqueous phase. I think it depends on what you are given.
by Charysa Santos 4G
Fri Jan 10, 2020 12:30 pm
Forum: Ideal Gases
Topic: Solving for K (coefficients)
Replies: 11
Views: 38

Re: Solving for K (coefficients)

The coefficients are attached to the particular reactant/product as you balance the equation. This coefficient becomes the exponent to the same reactant/product when calculating Q or K.
by Charysa Santos 4G
Fri Jan 10, 2020 12:24 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Do solids and liquids count in Q?
Replies: 5
Views: 26

Re: Do solids and liquids count in Q?

As the others have said, because Q is calculated in the same manner as K, solids and pure liquids are not included in the expression.
by Charysa Santos 4G
Sat Dec 07, 2019 12:38 pm
Forum: Air Pollution & Acid Rain
Topic: Acid Rain & Solutions
Replies: 4
Views: 66

Re: Acid Rain & Solutions

Some solutions to reducing the acidity of the rain could include producing less excess carbon dioxide or sulfur dioxide in the atmosphere so that these gases do not react with the H2O to form acids. I'm not sure if that answers your question about "lessening the acidity," though.
by Charysa Santos 4G
Sat Dec 07, 2019 12:34 pm
Forum: Ionic & Covalent Bonds
Topic: Boiling point
Replies: 3
Views: 25

Re: Boiling point

Yes, hydrogen bonding would result in a higher boiling point because compared to the PH3, Nitrogen has far greater electronegativity, which means that it is able to form much stronger (hydrogen) bonds which require more energy to break (as in boiling).
by Charysa Santos 4G
Sat Dec 07, 2019 12:30 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentates and Chelates
Replies: 4
Views: 24

Re: Polydentates and Chelates

Yes, because the polydentates have multiple binding sites, they are able to form a "claw" or loop around the metal cation.
by Charysa Santos 4G
Thu Dec 05, 2019 6:16 pm
Forum: Calculating the pH of Salt Solutions
Topic: HW 6D.11
Replies: 1
Views: 24

Re: HW 6D.11

Also, as a follow-up, how can we tell whether the metal -- in conjunction with the fact that it is attached to a conjugate base from a strong acid -- will produce either a basic or acidic pH in solution?
by Charysa Santos 4G
Thu Dec 05, 2019 6:09 pm
Forum: Calculating the pH of Salt Solutions
Topic: HW 6D.11
Replies: 1
Views: 24

HW 6D.11

For parts (e) and (f), I get that they're acidic because the conjugate bases come from strong acids (HCl and HNO3, respectively), but how would you be able to tell that the cation would have to be analyzed rather than the anion?
by Charysa Santos 4G
Thu Dec 05, 2019 12:28 am
Forum: Polyprotic Acids & Bases
Topic: HW 6C.17 Which is the stronger base?
Replies: 4
Views: 61

HW 6C.17 Which is the stronger base?

How do we find out which base is stronger -- either BrO- or C17H19O3N -- without knowing the pKb value?
by Charysa Santos 4G
Sun Dec 01, 2019 5:28 pm
Forum: Lewis Acids & Bases
Topic: acid v. base?
Replies: 16
Views: 73

Re: acid v. base?

Lewis bases usually have a lone pair so that it has electrons to donate while Lewis acids usually have a positive charge attached to them, meaning that they will likely accept an electron pair.
by Charysa Santos 4G
Sun Dec 01, 2019 5:24 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Test Grades
Replies: 6
Views: 50

Re: Test Grades

My test 2 grade is also a 0/50, as well... I believe that the TA's should input these at a later time, though. I'm not sure why, but my homework category is also a 0/50 even though my TA hasn't technically collected all of our homework yet.
by Charysa Santos 4G
Sun Dec 01, 2019 5:22 pm
Forum: Naming
Topic: How to Know the Charge of Ions
Replies: 7
Views: 46

Re: How to Know the Charge of Ions

If you want to calculate the charges using your knowledge of the periodic table and elemental charges that occur from it, you could do that, but it is time consuming and tedious. Like the person above mentioned, it would be in your best interest to just memorize these charges in order to conserve ti...
by Charysa Santos 4G
Sun Dec 01, 2019 5:18 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: structure of water
Replies: 4
Views: 26

Re: structure of water

Due to a water molecule's orbital geometry, only one of its lone pairs can be correctly oriented to 'bond' while the other lone pair will point away from the central atom.
by Charysa Santos 4G
Sun Dec 01, 2019 5:15 pm
Forum: Lewis Acids & Bases
Topic: bronsted vs lewis
Replies: 9
Views: 43

Re: bronsted vs lewis

The difference is that Bronsted acids and bases focus on the exchange of H+ ions (protons) while Lewis acids and bases deal with the exchange of electrons.
by Charysa Santos 4G
Sun Nov 24, 2019 6:10 pm
Forum: Hybridization
Topic: Strength of sigma vs pi bonds
Replies: 6
Views: 29

Strength of sigma vs pi bonds

Which is stronger: a sigma or a pi bond, and why?
by Charysa Santos 4G
Sun Nov 24, 2019 4:50 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: square planar vs tetrahedral
Replies: 5
Views: 32

Re: square planar vs tetrahedral

Using the VSEPR formula, AX4 is tetrahedral because it has no lone pairs (E). However, if it is AX4E2, the shape is square planar because the two lone pairs of electrons cause the bonded electrons to be arranged in a square shape, which allows them to be farthest from one another.
by Charysa Santos 4G
Sun Nov 24, 2019 4:46 pm
Forum: Hybridization
Topic: Sigma and Pi bonds
Replies: 13
Views: 57

Re: Sigma and Pi bonds

You must also indicate that there is a sigma bond present, in addition to the pi bond.
by Charysa Santos 4G
Sun Nov 24, 2019 4:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent Shape
Replies: 29
Views: 186

Re: Bent Shape

If the molecule has 3 regions of electron density, but one is a lone pair, then it can be bent (< 120 degrees). However, if the molecule has 4 regions of electron density, and two of them are lone pairs, then it can also be bent (< 109.5 degrees).
by Charysa Santos 4G
Sun Nov 24, 2019 4:42 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: pi and sigma bonds
Replies: 4
Views: 35

Re: pi and sigma bonds

Sigma bonds overlap end to end while pi bonds overlap side by side, with one nodal plane containing the internuclear axis.
by Charysa Santos 4G
Fri Nov 22, 2019 1:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bent v. angular
Replies: 20
Views: 107

Re: bent v. angular

Bent and angular refer to the same type of shape. Either works when naming AX2E and AX2E2 molecules.
by Charysa Santos 4G
Wed Nov 13, 2019 8:56 pm
Forum: Ionic & Covalent Bonds
Topic: HW 2D #9
Replies: 2
Views: 26

Re: HW 2D #9

Because smaller, highly charged cations (which, due to their lower electronegativity, have lose electrons) have smaller radii, the force of their positively-charged nucleus can better attract electrons, causing their polarizing power to be larger.
by Charysa Santos 4G
Wed Nov 13, 2019 8:46 pm
Forum: Ionic & Covalent Bonds
Topic: HW 2D #3
Replies: 2
Views: 23

Re: HW 2D #3

Essentially, if we go by periodic trends, Ba has the biggest electronegativity difference with Br compared to B and Be, making it the most ionic bond (ionic bond strength increases as the electronegativity difference increases between to atoms).
by Charysa Santos 4G
Wed Nov 13, 2019 8:38 pm
Forum: Dipole Moments
Topic: HW Question 3F1
Replies: 5
Views: 41

Re: HW Question 3F1

Because there is an uneven charge distribution (of electrons) between S and O (oxygen is more electronegative), there are dipole moments that form between them, creating dipole interactions.
by Charysa Santos 4G
Wed Nov 13, 2019 8:32 pm
Forum: Dipole Moments
Topic: Hydrogen bonds
Replies: 17
Views: 88

Re: Hydrogen bonds

No, only hydrogen atoms that are bonded to nitrogen, oxygen, and fluorine are able to form hydrogen bonds.
by Charysa Santos 4G
Wed Nov 13, 2019 8:29 pm
Forum: Dipole Moments
Topic: Do lone pairs repel more?
Replies: 5
Views: 35

Re: Do lone pairs repel more?

A lone electron pair will repel its surroundings more than a bonded electron would because its negative charge isn't being distributed/shared unlike the bonded pair, thus its negative charge and repulsion is more concentrated/stronger.
by Charysa Santos 4G
Tue Nov 12, 2019 7:21 pm
Forum: Bond Lengths & Energies
Topic: Van Der Waals BP
Replies: 6
Views: 40

Re: Van Der Waals BP

Ionic bonds are the strongest because the electrons are actually being donated to the more electronegative atom, and thus it would be hardest to pull these apart because it would take a relatively large amount of energy to remove electron(s) from such pairings
by Charysa Santos 4G
Tue Nov 12, 2019 7:16 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Help of 3F.11
Replies: 5
Views: 35

Re: Help of 3F.11

In order for a molecule to form hydrogen bonds, at least one hydrogen atom in the molecule must be bonded to either a oxygen, nitrogen, or fluorine atom.
by Charysa Santos 4G
Thu Nov 07, 2019 11:52 am
Forum: Bond Lengths & Energies
Topic: Resonance structure bond lengths?
Replies: 3
Views: 38

Re: Resonance structure bond lengths?

I think that the bond lengths are more of an arbitrary approximation to gauge which atoms share how many electrons between their electron clouds. The more electrons that they share in close proximity (i.e. how many bonds they have between each other), the closer the electrons will be between those a...
by Charysa Santos 4G
Thu Nov 07, 2019 11:47 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: D Subshell
Replies: 7
Views: 65

Re: D Subshell

The angular momentum quantum number for the d subshell is l=2, and its corresponding magnetic quantum numbers can have the values -2, -1, 0, 1,& 2 (5 in total). In each of these, there can be 2 electrons, which means that there are a total of 10 electrons that can be placed in the d subshell.
by Charysa Santos 4G
Thu Nov 07, 2019 11:44 am
Forum: Trends in The Periodic Table
Topic: ionic radii
Replies: 4
Views: 36

Re: ionic radii

An anion has a larger radius than its neutral atom because when you add an electron, the repulsive forces between the electrons is relatively greater than the pull of the positively-charged nucleus, thus causing the electrons to further apart, making the anion's radius larger.
by Charysa Santos 4G
Thu Nov 07, 2019 11:38 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Bohr Frequency
Replies: 6
Views: 46

Re: Bohr Frequency

When energy is absorbed by an atom, it is receiving energy, so the change in energy is positive, causing an electron to become excited and move from a lower energy level (let's say, n=1) to a higher energy level (i.e. n=2).
by Charysa Santos 4G
Tue Nov 05, 2019 4:04 pm
Forum: Ionic & Covalent Bonds
Topic: HW 2A.9 part (a)
Replies: 3
Views: 17

Re: HW 2A.9 part (a)

Ah, so because it's asking for a +2 metal, the ion's electron configuration for the d orbital is still the same as the neutral atom's because you're taking the 2 electrons from the s orbital... Understood!
by Charysa Santos 4G
Tue Nov 05, 2019 3:57 pm
Forum: Ionic & Covalent Bonds
Topic: HW 2A.9 part (a)
Replies: 3
Views: 17

Re: HW 2A.9 part (a)

And also, can someone explain why this also applies to part (b), and why it is Fe^2+?
by Charysa Santos 4G
Tue Nov 05, 2019 3:54 pm
Forum: Ionic & Covalent Bonds
Topic: HW 2A.9 part (a)
Replies: 3
Views: 17

HW 2A.9 part (a)

Why would the M^2+ metal for [Ar]3d^7 be Co^2+? Shouldn't it be Cu^2+ since the metal in question supposedly lost 2 electrons and now has the electron configuration [Ar]3d^7?
by Charysa Santos 4G
Fri Nov 01, 2019 1:33 pm
Forum: Trends in The Periodic Table
Topic: Noble Gases
Replies: 10
Views: 32

Re: Noble Gases

No, the noble gases do not follow the periodic trends (i.e. electronegativity, electron affinity, etc.) the way that the Group 1, 2, and so on elements do. They each have a complete valence shell, so they do not usually attract electrons.
by Charysa Santos 4G
Fri Nov 01, 2019 1:28 pm
Forum: Bond Lengths & Energies
Topic: bond lengths
Replies: 10
Views: 74

Re: bond lengths

The bond length is determined by how many bonded electrons there are. The more electrons are bonded (i.e. a triple bond in which 6 electrons are bonded), the shorter the bond length. That means that a triple bond has the shortest length (and has the most attraction/energy bringing the two atoms toge...
by Charysa Santos 4G
Fri Nov 01, 2019 1:24 pm
Forum: Bond Lengths & Energies
Topic: Lone electron pairs weakening bonds
Replies: 4
Views: 21

Re: Lone electron pairs weakening bonds

The lone pairs of the electrons found on neighboring atoms weaken these bonds due to electron repulsion. The neighboring atoms in a molecule that have lone pair electrons are not bonded as tightly because the lone pair electrons of both atoms repel one another.
by Charysa Santos 4G
Fri Nov 01, 2019 1:13 pm
Forum: Trends in The Periodic Table
Topic: Electron Affinity
Replies: 8
Views: 29

Re: Electron Affinity

Electron affinity increases rightwards across a row, and then decreases downward, down a group/column.
by Charysa Santos 4G
Fri Nov 01, 2019 1:11 pm
Forum: Ionic & Covalent Bonds
Topic: Anions and Cations
Replies: 9
Views: 50

Re: Anions and Cations

Anions are generally larger than its corresponding neutral atom because adding electrons increases the number of electron-electron repulsion interactions that take place. Cations are smaller than the corresponding neutral atoms, since the valence electrons, which are furthest away from the nucleus, ...
by Charysa Santos 4G
Sun Oct 27, 2019 9:29 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy
Replies: 9
Views: 27

Re: Ionization Energy

Just think of it as having to insert energy (+) in order to take out the electron because the electron is being held to the atom by the positive charge of the nucleus.
by Charysa Santos 4G
Sun Oct 27, 2019 9:22 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 4
Views: 38

Re: Resonance Structures

If there are multiple places where the center atom can bond with the outer atoms and these bonds are interchangeable, I believe that you just have to count/take account of all of these different forms to get the number of resonance structures.
by Charysa Santos 4G
Sun Oct 27, 2019 9:20 pm
Forum: Trends in The Periodic Table
Topic: Electron affinity.
Replies: 8
Views: 28

Re: Electron affinity.

Electron affinity is simply the potential of an atom to accept an electron (or more than one) based on its size (how many shells does it have/how far is its valence shell from its nucleus) and whether or not it almost has a full valence shell (lefthand side of the periodic table of elements tend to ...
by Charysa Santos 4G
Sun Oct 27, 2019 9:16 pm
Forum: Electronegativity
Topic: Electronegativity
Replies: 6
Views: 36

Re: Electronegativity

Fluorine is the most electronegative element because it almost has a full valence shell, and since its atomic radius is relatively smaller than the other elements in its column/group, the positively-charged nucleus has a higher chance of attracting the last negatively charged electron to fill this s...
by Charysa Santos 4G
Sun Oct 27, 2019 9:12 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic VS. Covalent Bond
Replies: 8
Views: 36

Re: Ionic VS. Covalent Bond

An ionic bond is usually between a cation and an anion, and there is a transfer of electrons between the two. However, with covalent bonds, the electrons are merely shared between the two atoms.
by Charysa Santos 4G
Fri Oct 18, 2019 1:27 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect
Replies: 6
Views: 33

Re: Photoelectric Effect

I believe that it is only momentarily "removed" from the metal, but the only possible way for it to "leave" the metal is if there is excess energy (if the photon's energy is greater than the energy to remove the electron) and in that situation, the electron is ejected from the me...
by Charysa Santos 4G
Fri Oct 18, 2019 1:23 pm
Forum: *Shrodinger Equation
Topic: Schrodinger and De Broglie's Equation
Replies: 3
Views: 28

Re: Schrodinger and De Broglie's Equation

I forgot to add that you can also use De Broglie's if you are given the wavelength and you need to find either mass or velocity (λ = h/mv).
by Charysa Santos 4G
Fri Oct 18, 2019 1:19 pm
Forum: *Shrodinger Equation
Topic: Schrodinger and De Broglie's Equation
Replies: 3
Views: 28

Re: Schrodinger and De Broglie's Equation

If you're dealing with quantum numbers and atomic orbitals in a question, you will most likely use Schrodinger's wave function equation. De Broglie's would be to find the wavelength (for instance, if you are given the mass and/or velocity of an object, then you would use De Broglie's equation).
by Charysa Santos 4G
Thu Oct 17, 2019 8:25 pm
Forum: Properties of Electrons
Topic: HW Question Topic 1B #1B.5
Replies: 2
Views: 24

Re: HW Question Topic 1B #1B.5

Oh, I see, I didn't realize at first that it was a constant. Thank you!
by Charysa Santos 4G
Thu Oct 17, 2019 5:55 pm
Forum: Properties of Electrons
Topic: HW Question Topic 1B #1B.5
Replies: 2
Views: 24

HW Question Topic 1B #1B.5

In the solutions manual, can someone explain where the 1.6022x10^-19 J*Ev^-1 comes from when converting the given value in the problem to Joules?
by Charysa Santos 4G
Fri Oct 11, 2019 1:13 pm
Forum: Limiting Reactant Calculations
Topic: percent yield
Replies: 10
Views: 157

Re: percent yield

It depends on what you are given. They will usually ask for it, or if they give you the experimental data for something like a problem where you have to find the empirical formula, then you should calculate it to help you with the final answer.
by Charysa Santos 4G
Fri Oct 11, 2019 1:08 pm
Forum: Balancing Chemical Reactions
Topic: Fractions
Replies: 20
Views: 190

Re: Fractions

I remember Prof. Lavelle suggesting that we should convert the fractional stoichiometric coefficients into whole integers.
by Charysa Santos 4G
Fri Oct 11, 2019 1:06 pm
Forum: SI Units, Unit Conversions
Topic: Showing work/ rearranging equations
Replies: 8
Views: 100

Re: Showing work/ rearranging equations

My TA said that to be safe and secure partial credit in the case that your final answer is somehow incorrect, you should show as many steps as possible/necessary to indicate each step of a problem. It is totally up to you, though.
by Charysa Santos 4G
Fri Oct 11, 2019 10:07 am
Forum: Limiting Reactant Calculations
Topic: Fundamentals M Homework Problem M.11
Replies: 3
Views: 83

Re: Fundamentals M Homework Problem M.11

Oh okay, fair enough. I was just confused because the solution shows that there is an excess of oxygen (for example, for the first reaction it shows: excess O2 = 5.77g - 4.47g = 1.30g O2). But now I think I understand why O2 is still the limiting reactant.
by Charysa Santos 4G
Thu Oct 10, 2019 10:02 pm
Forum: Limiting Reactant Calculations
Topic: Fundamentals M Homework Problem M.11
Replies: 3
Views: 83

Fundamentals M Homework Problem M.11

Is there another way to find the limiting reactant aside from converting the grams of P into the grams of O2? I don't understand how converting the grams into O2 would tell you that it is the limiting reactant. Can anyone clarify?
by Charysa Santos 4G
Fri Oct 04, 2019 10:16 am
Forum: Empirical & Molecular Formulas
Topic: Test Materials
Replies: 13
Views: 123

Re: Test Materials

Does anyone know if we need to memorize all of the SI unit conversions?
by Charysa Santos 4G
Fri Oct 04, 2019 10:13 am
Forum: SI Units, Unit Conversions
Topic: SI
Replies: 5
Views: 36

Re: SI

I believe that he said that most of the SI unit conversions would be given on the test (don't quote me on this), but it would also be good to have them memorized anyways to make working through homework problems easier. Feel free to correct me if I'm wrong though, I'm not 100% sure.
by Charysa Santos 4G
Fri Oct 04, 2019 9:56 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Formula Units
Replies: 4
Views: 64

Re: Formula Units

Formula units just refer to an ionic compound's empirical formula, right? In any case, you would just multiply by Avogadro's constant (6.022 × 10^23 mol-1) to find the formula units.
by Charysa Santos 4G
Fri Oct 04, 2019 9:44 am
Forum: Limiting Reactant Calculations
Topic: 2A + 1B ---> 3C
Replies: 2
Views: 30

Re: 2A + 1B ---> 3C

If 1 mole of A reacted with 1 mole of B, but the reaction requires *2* moles of A to react with every 1 mole of B, then there is a limited amount of A present and that limits the amount of product that can be formed. The reaction would still proceed, with 1 mole of A reacting with 0.5 mole of B (the...
by Charysa Santos 4G
Thu Oct 03, 2019 2:38 pm
Forum: Administrative Questions and Class Announcements
Topic: Chemistry Community Posts due date?
Replies: 3
Views: 62

Re: Chemistry Community Posts due date?

The TA for my section never specified, but to be safe, I would post by tomorrow. That's when the homework is going to be due for this week, anyways

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