Search found 44 matches

by Briana Lopez 4K
Sun Mar 17, 2019 9:46 am
Forum: Second Order Reactions
Topic: Plotting second order reactions
Replies: 3
Views: 12

Re: Plotting second order reactions

The equation for the second order integrated rate law is
kt + 1/[A]o = 1/[A]
where k is a positive slope in the straight line graph
by Briana Lopez 4K
Sun Mar 17, 2019 9:45 am
Forum: General Rate Laws
Topic: fast step before slow step
Replies: 2
Views: 14

Re: fast step before slow step

The slow step requires more energy for the reaction to achieve, and in turn, more time which is why it is the rate-determining step
by Briana Lopez 4K
Sun Mar 17, 2019 9:43 am
Forum: Zero Order Reactions
Topic: Zero order reaction
Replies: 8
Views: 16

Re: Zero order reaction

For instance, a liquid or solid would not affect the rate
by Briana Lopez 4K
Sun Mar 17, 2019 9:41 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pKa and pKb
Replies: 4
Views: 14

Re: pKa and pKb

when given pKa and asked for ph, solve for Ka with pKa= -logKa which would mean 10^(-pKa)= Ka Then, if the reaction is acidic, find the Ka equilibrium equation for the reaction Usually, an initial Molarity will be given for the Reactant Once the Ka equation is written, set it equal to the Ka value c...
by Briana Lopez 4K
Sun Mar 17, 2019 9:36 am
Forum: Phase Changes & Related Calculations
Topic: heating curves
Replies: 3
Views: 22

Re: heating curves

That heating curve is specific to water. Other molecules would have different heating curves and heat capacities.
by Briana Lopez 4K
Sun Mar 17, 2019 9:33 am
Forum: Second Order Reactions
Topic: rate
Replies: 1
Views: 9

Re: rate

The integrated rate law for a second-order reaction is
kt + 1/[A]o = 1/[A}

The graph has a positive k, straight line slope which means that over time concentration of A is increasing

For the general rate law, the units for K would be 1/(M * s)
by Briana Lopez 4K
Sun Mar 17, 2019 9:28 am
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: zero order reaction
Replies: 2
Views: 14

Re: zero order reaction

The slope is -k because the integrated rate law for zero order is
-kt + [A]o = [A]

similar to the straight line y= mx + b

[A] = -kt + [A]o
by Briana Lopez 4K
Sun Mar 17, 2019 9:24 am
Forum: Balancing Redox Reactions
Topic: Balancing alkaline solutions
Replies: 1
Views: 7

Re: Balancing alkaline solutions

This is because OH- is used specifically for alkaline or basic solutions. Whereas H+ is associated with acidic solutions
by Briana Lopez 4K
Sun Mar 17, 2019 9:23 am
Forum: General Rate Laws
Topic: mmol units
Replies: 2
Views: 13

Re: mmol units

For mmols you would need to divide by 1000 because 1000 mmols equals 1 mol. As long as they all have the same units, then the problem should be fine
by Briana Lopez 4K
Sun Mar 17, 2019 9:21 am
Forum: General Rate Laws
Topic: Slow elementary step
Replies: 2
Views: 12

Re: Slow elementary step

Also, the slowest step is the one that requires the most energy to overcome such as the Activation Energy
by Briana Lopez 4K
Sun Mar 17, 2019 9:20 am
Forum: Balancing Redox Reactions
Topic: How to balance half reaction
Replies: 5
Views: 17

Re: How to balance half reaction

In an alkaline solution OH- is used to balance the number of oxygen and hydrogen atoms on both sides. Then electrons are used to balance the charge
by Briana Lopez 4K
Thu Jan 17, 2019 4:08 pm
Forum: Ideal Gases
Topic: 5% rule
Replies: 12
Views: 159

5% rule

How do you use the 5% rule if there is more than one reactant? In the example in class it was CH3COOH-> H30+ + CH3COO- and the percentage is calculated by dividing (1.3 x 10^-3)/(0.10) * 100% which equals 1.3% but how would you do it if it were this for instance?? 2N2 + O2 —> 2N2O and our x= 7.15 x ...
by Briana Lopez 4K
Fri Jan 11, 2019 11:29 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: equilibrium
Replies: 3
Views: 38

Re: equilibrium

Also, when a reaction is said to be at equilibrium, it means that the products and reactants are being produced at the same rate. A chemical reaction at equilibrium represents a fixed P/R=K ratio. K is independent of concentration which means it will not change when there is more of one product or r...
by Briana Lopez 4K
Fri Jan 11, 2019 11:16 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp
Replies: 9
Views: 68

Re: Kp

Additionally, when using Kp, partial pressure has to be calculated where when Kc is used, the concentrations have to be calculated
by Briana Lopez 4K
Sun Jun 10, 2018 8:52 pm
Forum: Dipole Moments
Topic: Non-polar molecules
Replies: 4
Views: 157

Re: Non-polar molecules

A molecule as a whole can be Non-polar with polar bonds as long as they cancel out mmhm. Having one dipole movement makes it polar molecule if there is nothing to cancel out with it. so
C-Cl is polar bc of EN diff
but Cl-C-Cl is nonpolar because two dipole movements cancel out
by Briana Lopez 4K
Sun Jun 10, 2018 8:46 pm
Forum: Dipole Moments
Topic: Dipole Moment understanding
Replies: 5
Views: 231

Re: Dipole Moment understanding

Additionally, it is also when there is a difference in electronegativity great enough for it to be a polar bond. Nonpolar molecules have no dipole movements because the electrons are shared equally, so there are no partial charges. Polar bonds have partial charges because there is an unequal sharing...
by Briana Lopez 4K
Sun Jun 10, 2018 8:36 pm
Forum: Lewis Acids & Bases
Topic: CH3COOH vs CH3OH Acid Strength
Replies: 2
Views: 426

CH3COOH vs CH3OH Acid Strength

Why is CH3COOH a stronger acid than CH3OH?
by Briana Lopez 4K
Fri Jun 08, 2018 2:40 pm
Forum: Identifying Acidic & Basic Salts
Topic: salt in water
Replies: 2
Views: 122

salt in water

Dr. Lavelle said in the lecture today that salts do not affect the pH of water. Why is this? And how is related to not affecting the boiling point as well?
by Briana Lopez 4K
Fri Jun 08, 2018 1:52 am
Forum: Bronsted Acids & Bases
Topic: H3O vs H2O
Replies: 5
Views: 191

Re: H3O vs H2O

Also, since acids donate hydrogen ions, if the product has less hydrogen than the one in the reactant side, then it is easier to determine the acid.
by Briana Lopez 4K
Fri Jun 08, 2018 1:22 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Relative acidity
Replies: 2
Views: 156

Re: Relative acidity

Also, the bonds for a strong acid are very easy to break when they are dissociated in water. This means that the H+ ions will lose an electron and it will go to the other element, the weak conjugate base. EX: HCL -> H+ + Cl- Strong Acid -> H+ + Weak Conjug Base ->this WCB is stable and unreactive be...
by Briana Lopez 4K
Thu Jun 07, 2018 4:28 pm
Forum: Dipole Moments
Topic: dipole moments
Replies: 9
Views: 249

Re: dipole moments

Yeah, he larger the difference in Electronegativity, the more powerful the dipole moment. Also, if there is a strong dipole moment and there is a very unfair sharing of electrons, then the bond is weaker. This is why polar bonds are weaker than nonpolar bonds. Equal sharing = stronger bond= nonpolar...
by Briana Lopez 4K
Thu Jun 07, 2018 4:23 pm
Forum: Hybridization
Topic: Hybrid Orbitals
Replies: 3
Views: 147

Re: Hybrid Orbitals

In class, he said something about how it is written differently, but the more clear way is sp3d
by Briana Lopez 4K
Wed Jun 06, 2018 2:39 pm
Forum: Lewis Acids & Bases
Topic: Ka
Replies: 5
Views: 196

Ka

What does Ka represent and why is it significant?
by Briana Lopez 4K
Tue May 29, 2018 6:07 pm
Forum: Ionic & Covalent Bonds
Topic: Double/Triple Bonds
Replies: 8
Views: 221

Re: Double/Triple Bonds

It will also form double or triple bonds to become more stable
by Briana Lopez 4K
Tue May 29, 2018 5:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pairs
Replies: 2
Views: 49

Re: Lone Pairs

Vsepr.jpg A lone pair of electrons repels more than a bonded pair of electrons because LPE are less stable and have more energy. An electron bond and a lone pair are both considered regions of electron density, and regions of e- density repel. The LPE repel more which means that the bond angles wil...
by Briana Lopez 4K
Tue May 29, 2018 5:04 pm
Forum: Bond Lengths & Energies
Topic: HW question 4.1
Replies: 5
Views: 180

Re: HW question 4.1

The lone pairs are not shown, but if it were, then one would most likely be on top and the VSEPR would be AX2E1. The bond angle would be less than 120, but all of the angles would be about that much.
by Briana Lopez 4K
Mon May 28, 2018 4:42 pm
Forum: Dipole Moments
Topic: London Forces
Replies: 7
Views: 205

Re: London Forces

London forces are AKA Dispersion forces, Induced Dipole-Induced Dipole, and Van der Waals forces. They occur when there is an uneven distribution of electrons causing a temporary dipole moment and temporary partial charge. This temporary dipole creates another dipole called a temporary induced dipol...
by Briana Lopez 4K
Mon May 28, 2018 4:08 pm
Forum: Dipole Moments
Topic: Dipole
Replies: 4
Views: 129

Re: Dipole

Yes, the arrow would go towards the more EN atom.
an example would be H2O, since O is more EN than H the arrow will point towards O
by Briana Lopez 4K
Mon May 28, 2018 2:28 pm
Forum: Ionic & Covalent Bonds
Topic: Partial charge or full charge
Replies: 4
Views: 136

Re: Partial charge or full charge

A nonpolar molecule will have no charge and a polar molecule will have partial charges. A partial negative would go on the more EN side and a partial positive would go on the less EN side of the molecule because the electron concentration goes more towards the more EN element.
by Briana Lopez 4K
Mon May 28, 2018 1:23 pm
Forum: Resonance Structures
Topic: Radicals importance
Replies: 3
Views: 145

Re: Radicals importance

The way to identify a radical would be if the molecule has an uneven number of electrons and at least one unpaired electron
by Briana Lopez 4K
Sun May 06, 2018 5:33 pm
Forum: Trends in The Periodic Table
Topic: Stability of Cl vs Cl-
Replies: 6
Views: 162

Stability of Cl vs Cl-

Since Cl has 7 valence electrons and only needs 1 more to complete its octet, once it obtains an electron to become Cl-, is it more stable as this ion? And does stability mean that it is less reactive?
by Briana Lopez 4K
Mon Apr 30, 2018 1:47 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: f orbitals
Replies: 3
Views: 79

Re: f orbitals

Yeah we don't have to worry about those for now. The other 3 are though (s, p, d) (sphere, propeller, daisy)
by Briana Lopez 4K
Mon Apr 30, 2018 1:42 am
Forum: Properties of Electrons
Topic: ejecting electrons
Replies: 4
Views: 139

Re: ejecting electrons

Amplitude relates to the intensity of the light. If there is a higher wavelength, then there are more photons and a brighter light.
by Briana Lopez 4K
Mon Apr 30, 2018 1:39 am
Forum: DeBroglie Equation
Topic: work threshold
Replies: 1
Views: 93

Re: work threshold

is this for the energy per photon equation?
E= ch/λ?
by Briana Lopez 4K
Mon Apr 30, 2018 1:37 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Difference between orbitals
Replies: 4
Views: 81

Re: Difference between orbitals

The shapes are... s is a "sphere", p is a "propeller", d is a "daisy" and f is irrelevant right now
by Briana Lopez 4K
Mon Apr 30, 2018 1:31 am
Forum: Einstein Equation
Topic: p=mv [ENDORSED]
Replies: 3
Views: 195

Re: p=mv [ENDORSED]

Yeah I believe the equation for power is force x velocity
by Briana Lopez 4K
Mon Apr 30, 2018 1:24 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: E=R(1/n-1/n)?
Replies: 7
Views: 245

Re: E=R(1/n-1/n)?

ΔE=Ef-Ei
En= -hR/n^2

ΔE= -hR/nf^2 - (-hR/ni^2)
ΔE= hR/ni^2 - hR/nf^2

V=R(1/ni^2 - 1/nf^2)
ΔE/h= R(1/ni^2 - 1/nf^2)
ΔE=hR(1/ni^2 - 1/nf^2)
ΔE=hR/ni^2 - hR/nf^2
by Briana Lopez 4K
Mon Apr 30, 2018 1:05 am
Forum: Einstein Equation
Topic: Kinetic Energy vs Power
Replies: 2
Views: 88

Re: Kinetic Energy vs Power

The P in p=mv stands for momentum. The equation for Power is Force x Velocity. In a case where we are only given momentum, I think we can solve for Kinetic energy ( E=threshhold+KE ) if we substitute other equations for E and get it in terms of p=mv E = threshold + KE hv = threshold + KE KE = hv - t...
by Briana Lopez 4K
Sun Apr 29, 2018 11:43 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: test 2 #4
Replies: 4
Views: 141

Re: test 2 #4

I had trouble with that one too for the same reason. I assumed it was from n=1 to n=2, but wasn't sure.
The formula I used was the En= -hR/n^2 which I believe is the same as the V= R((1/n1^2)-(1/n2^2))
by Briana Lopez 4K
Sun Apr 22, 2018 11:59 pm
Forum: DeBroglie Equation
Topic: Wavelength= (h/p) [ENDORSED]
Replies: 7
Views: 269

Re: Wavelength= (h/p) [ENDORSED]

Thank you this is helpful., also i think the mass of an electron is 9.10938356 × 10-31 kilograms
by Briana Lopez 4K
Sun Apr 22, 2018 11:57 pm
Forum: Properties of Light
Topic: amplitude and intensity
Replies: 11
Views: 253

Re: amplitude and intensity

It is important to just keep in mind that increasing the intensity of light does not cause electrons to be ejected
by Briana Lopez 4K
Sun Apr 22, 2018 7:39 pm
Forum: General Science Questions
Topic: Tools for remembering equations
Replies: 5
Views: 448

Re: Tools for remembering equations

I don't know a good song, but PLF said a way to help memorize the v= c/λ is
"Hey what's new? :D....speed of light over lambda" Haha I'd say it's pretty cute
by Briana Lopez 4K
Thu Apr 12, 2018 11:42 am
Forum: SI Units, Unit Conversions
Topic: Sig Figs
Replies: 9
Views: 300

Re: Sig Figs

Also, this may come in handy when we start using them more, but it was mentioned in class how the final answer should have the least amount of significant figures. If one part of the problem has 3 sig figs and the other part has 6 sig figs, then I think your final answer should be rounded to 3 sig f...
by Briana Lopez 4K
Thu Apr 12, 2018 11:32 am
Forum: SI Units, Unit Conversions
Topic: Moles mols mol? [ENDORSED]
Replies: 18
Views: 565

Re: Moles mols mol? [ENDORSED]

Mole/s is the spelled out version of the abbreviations "mols" and "mol".
For example, Millimeter would be abbreviated as "mm"
In problems, usually abbreviations are used, so the "mol"

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