Search found 59 matches

by Hannah Yates 1K
Mon Mar 11, 2019 2:24 pm
Forum: Zero Order Reactions
Topic: Half-life
Replies: 6
Views: 83

Re: Half-life

It’s just the amount of time it takes for the reactant to become half its original concentration. What’s interesting with half life is that this time never changes no matter the amount of concentration you start with.
by Hannah Yates 1K
Mon Mar 11, 2019 2:21 pm
Forum: First Order Reactions
Topic: Integration
Replies: 3
Views: 45

Re: Integration

Lavelle just showed us how to do it becasue it will help you understand how the two equations are related, but you will most likely not be asked to integrate a rate law on a test. I believe that the integrated rate laws are all on the equation sheet.
by Hannah Yates 1K
Mon Mar 11, 2019 2:19 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: how is kinetics different?
Replies: 17
Views: 230

Re: how is kinetics different?

Even if someone is thermodynamically favored, the reaction may not occur becasue of the rate of reaction. For example, Graphite is more Thermodynamically favored than diamond, but the activation energy for that reaction is extremely high for some reason so Diamond will never spontaneously turn into ...
by Hannah Yates 1K
Mon Mar 11, 2019 2:16 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Melting of ice
Replies: 9
Views: 165

Re: Melting of ice

The melting of ice on a hot summers day would be spontaneous, so delta g would be negative
by Hannah Yates 1K
Sun Mar 03, 2019 3:29 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Recharging Batteries [ENDORSED]
Replies: 8
Views: 209

Re: Recharging Batteries [ENDORSED]

IsabelLight2H wrote:I think it's because the battery is absorbing energy. A favorable reaction releases energy.


Exactly. For example, we supply energy to our phone battery by plugging it in.
by Hannah Yates 1K
Sun Mar 03, 2019 3:23 pm
Forum: Balancing Redox Reactions
Topic: Acidic vs basic solutions
Replies: 10
Views: 138

Acidic vs basic solutions

What’s the difference between balancing is acid and base?
by Hannah Yates 1K
Thu Feb 21, 2019 9:24 am
Forum: Balancing Redox Reactions
Topic: Helpful acronym for Redox Rxns
Replies: 2
Views: 51

Helpful acronym for Redox Rxns

Hello, as I was studying Redox reactions, I found an acronym that I found very helpful when thinking about the movement of electrons!
It’s OIL RIG!
Oxidation is Loss (of electrons)
Reduction is Gain (of electrons)
Hope this helps everyone!!!
by Hannah Yates 1K
Thu Feb 21, 2019 9:15 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 912307

Re: Post All Chemistry Jokes Here

Hello, while I was procrastinating my studies, I drew Lavelle! Thought I would share this with all of you!! Thanks for being a great professor !
by Hannah Yates 1K
Thu Feb 21, 2019 9:09 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7348
Views: 912307

Re: Post All Chemistry Jokes Here

@ the midterm thissss yearrrrrr
by Hannah Yates 1K
Tue Feb 12, 2019 3:31 pm
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Replies: 179
Views: 6739

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

Should number 4 on the midterm review be when delta T = 0?
by Hannah Yates 1K
Tue Feb 12, 2019 3:19 pm
Forum: Administrative Questions and Class Announcements
Topic: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)
Replies: 179
Views: 6739

Re: DOWNLOAD SESSION WORKSHEETS HERE - Sun 7-9PM (Karen)

For #6, how do we know that work is equal to 0? I was wondering the same thing. What I came up with was that is you use pv=nrt to find deltaV then you can see that since pressure, temperature, and R are constant the change in volume will depend on the change in moles. The equation has a 1:1 ratio f...
by Hannah Yates 1K
Sun Feb 10, 2019 4:22 pm
Forum: Phase Changes & Related Calculations
Topic: Trouton's Rule
Replies: 2
Views: 51

Re: Trouton's Rule

I believe that Troutons rule is just stating that many liquids have about the same enthalpy of vaporization. Which means that they all take about the same amount of energy to vaporize.
by Hannah Yates 1K
Sun Feb 10, 2019 4:18 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: methods
Replies: 8
Views: 142

Re: methods

If you are given (or took to look up) the bond enthalpies, you then just have to use the equation that someone put above.
by Hannah Yates 1K
Sun Feb 10, 2019 4:15 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Q of reaction and Q of calorimeter
Replies: 1
Views: 37

Q of reaction and Q of calorimeter

I keep seeing the equation -qcal = qrxn. Can someone explain what this means.
by Hannah Yates 1K
Sun Feb 03, 2019 10:23 pm
Forum: Calculating Work of Expansion
Topic: Work sign changes
Replies: 3
Views: 71

Re: Work sign changes

I think work is negative when the system is doing work, and positive when the system is getting work done to it. So when a system expands, work is negative, and when a system is compressed, work is positive.
I might be wrong though
by Hannah Yates 1K
Sun Feb 03, 2019 10:21 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated systems
Replies: 2
Views: 45

Isolated systems

What is the importance of an isolated system? It seems like they dont really do anything?
by Hannah Yates 1K
Sun Feb 03, 2019 10:20 pm
Forum: Phase Changes & Related Calculations
Topic: State Function
Replies: 10
Views: 102

Re: State Function

What isn’t a state function? Can someone give an example?
by Hannah Yates 1K
Thu Jan 24, 2019 11:27 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: endothermic vs exothermic
Replies: 6
Views: 111

endothermic vs exothermic

What is the difference between endothermic and exothermic?
Also, since we just started discussing this on Wednesday, will we need to understand how it applies to Le Chatelier’s Principle?
by Hannah Yates 1K
Thu Jan 24, 2019 11:24 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Calculating Q
Replies: 11
Views: 153

Calculating Q

When do you calculate Q? I am having some trouble understanding why you would need this and when to use it.
by Hannah Yates 1K
Thu Jan 24, 2019 11:23 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Neutral solutions
Replies: 2
Views: 52

Neutral solutions

I have written in my notes “ if [h3o+] is less than 10^-7, then the solution is considered neutral”.
Can some one explain what this means, and why it is neutral?
by Hannah Yates 1K
Sat Jan 19, 2019 2:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solving weak acid/base dissociations
Replies: 4
Views: 55

Re: Solving weak acid/base dissociations

Depends. The reason you use the quadratic is because that is the values that the ice table gives you, but is the Ka is less than 10^-3, you can assume that when you are subtracting x from the initial concentration of the weak acid, that x is negligible because it is so small. This assumptions gets r...
by Hannah Yates 1K
Sat Jan 19, 2019 1:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Determining when k is small or big
Replies: 2
Views: 44

Determining when k is small or big

K is big when it is greater than 10^3 and small when it is less than K^-3, but what is it when the K value is in between 10^3 and 10^-3
by Hannah Yates 1K
Sat Jan 19, 2019 1:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K - small verses big
Replies: 4
Views: 66

K - small verses big

What does a small Ka mean verses a large kb?
by Hannah Yates 1K
Thu Jan 10, 2019 5:31 pm
Forum: Ideal Gases
Topic: Value of K
Replies: 6
Views: 89

Re: Value of K

When K is Larger than 1, the forward reaction is favored and more products are being produced.
When K is smaller than 1, the reverse reaction is favored and more reactants are being produced.
by Hannah Yates 1K
Thu Jan 10, 2019 5:24 pm
Forum: Ideal Gases
Topic: Q and K [ENDORSED]
Replies: 35
Views: 1075

Re: Q and K [ENDORSED]

No difference in the way you calculate Q and K, but there is a major difference in what they mean. Q means the ratio of Products and reactants at any given point of the reaction, but K is the ratio of Products and Reactants at equalibrium. When comparing Q and K, it can tell us which reaction rate i...
by Hannah Yates 1K
Thu Jan 10, 2019 5:17 pm
Forum: Ideal Gases
Topic: Units
Replies: 19
Views: 224

Re: Units

Use Kelvin. In most equations with temperature, you always use Kelvin
by Hannah Yates 1K
Fri Dec 07, 2018 8:18 pm
Forum: Conjugate Acids & Bases
Topic: Chemical Equations
Replies: 6
Views: 170

Re: Chemical Equations

In the reactions HCL + H20 -> Cl- + H30+
HCl- is the acid with the conjugate base of Cl-
H20 is the base with the conjugate acid of H3O+
by Hannah Yates 1K
Fri Dec 07, 2018 8:15 pm
Forum: Polyprotic Acids & Bases
Topic: Significance of Polyprotic Acids & Bases
Replies: 6
Views: 186

Re: Significance of Polyprotic Acids & Bases

A lot of these polyprotic substances are things that have an ion in them that he went over in class when discussing Lewis structures. It’s important to note that these ions are stabilized with resonance so they are good acids
by Hannah Yates 1K
Fri Dec 07, 2018 8:11 pm
Forum: Amphoteric Compounds
Topic: Difference between amphoteric and amphiprotic?
Replies: 4
Views: 98

Re: Difference between amphoteric and amphiprotic?

An example of something that is amphoteric is Water
An example of something that is amphiprotic is HSO4-
by Hannah Yates 1K
Fri Nov 30, 2018 6:15 pm
Forum: Amphoteric Compounds
Topic: Amphoteric Oxides
Replies: 4
Views: 254

Re: Amphoteric Oxides

I do believe we have to memorize them. It will probably be useful to know them so that you understand why a reaction with them may act a certian way
by Hannah Yates 1K
Fri Nov 30, 2018 6:12 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Transition Metals
Replies: 4
Views: 65

Re: Transition Metals

Transition metals are good for electron transfer because they have multiple oxidation states.
by Hannah Yates 1K
Fri Nov 30, 2018 6:11 pm
Forum: Naming
Topic: Coordination number
Replies: 10
Views: 348

Re: Coordination number

Can the term coordination number apply to all molecules? or only some? I’m pretty sure a coordination number can only apple to coordination compound, which is the product of a Lewis acid-base reaction in which neutral molecules or anions (called ligands) bond to a central metal atom (or ion) by coo...
by Hannah Yates 1K
Thu Nov 22, 2018 8:30 pm
Forum: Hybridization
Topic: Sixth Edition, Example 4.6
Replies: 2
Views: 53

Re: Sixth Edition, Example 4.6

The numbers are just something extra he wrote out on the board, but they aren’t really talked about in the textbook. I would still recommend putting it on the test if asked.
by Hannah Yates 1K
Thu Nov 22, 2018 8:27 pm
Forum: Hybridization
Topic: unhybridized pi bonds
Replies: 2
Views: 102

Re: unhybridized pi bonds

I am also not too sure on my answer, but I am pretty sure that a sigma bond has just hybridized orbitals, but the reason a pi bond can form is because of an extra (not hybridized) p orbital. This allows for a double and triple bond to form.
by Hannah Yates 1K
Thu Nov 22, 2018 8:23 pm
Forum: Hybridization
Topic: Help with Confusion
Replies: 6
Views: 118

Re: Help with Confusion

I think the most important thing to know is to understand what makes something a sigma bond and what makes something a pi bond. I don’t think he would directly ask us to draw how they are bonded, more like ask us to explain how they are bonded. In order to explain, it could help to draw a picture.
by Hannah Yates 1K
Fri Nov 16, 2018 2:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Distance from Central Atom
Replies: 8
Views: 92

Re: Distance from Central Atom

The completely dark wedge represents the atom coming towards you, and the dashed wedge represents the atom going away. I’m not quite sure why, but I also don’t think it matters that much as long as you know that they are on a diferent plane.
by Hannah Yates 1K
Fri Nov 16, 2018 2:26 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Tetrahedral shape
Replies: 5
Views: 103

Re: Tetrahedral shape

A molecule can always be slightly distorted. This can happen because of what atoms are attached to central atom. If all 4 of the attached atoms are the same, then you will have a normal tetrahedral shape, but the second that one of the atoms are different, there will be a slight distortion to the mo...
by Hannah Yates 1K
Fri Nov 16, 2018 2:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Octahedral Shape
Replies: 4
Views: 80

Re: Octahedral Shape

There are 6 areas of electron density, but only 4 bonding regions. This is because there are two electron pairs. The molecular geometry of the molecule is only dependent on the bonding regions. While the number of areas of electron density says thats the shape is octahedral, the actual shape is squa...
by Hannah Yates 1K
Fri Nov 09, 2018 3:43 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: Boiling point
Replies: 12
Views: 238

Re: Boiling point

Rod and spherical shaped were just an example of two possible shapes. He then used pentane and 2,2-dimethylpropane as two examples of those shapes. Pentane is rod shaped and 2,2-dimethylpropane is spherical. Pentane has a higher boiling point because the intermolecular forces are stronger because th...
by Hannah Yates 1K
Fri Nov 09, 2018 3:35 pm
Forum: Lewis Structures
Topic: Formal charge question
Replies: 9
Views: 189

Re: Formal charge question

Formal charge is usually what I check last. It’s a good way to check that you didn’t do something completely wrong because if you had a formal charge of like -4 somewhere, thats a big clue that there is a big mistake. If the formal charges all make sense and are where they should be (negative on mos...
by Hannah Yates 1K
Fri Nov 09, 2018 3:30 pm
Forum: Dipole Moments
Topic: Dipole - Dipole vs. Hydrogen Bonding
Replies: 4
Views: 83

Re: Dipole - Dipole vs. Hydrogen Bonding

H-Bonding isn’t actually a type of bond. A lot of people get this confused because of the word bonding in it. H-Bonding is another type of Intermolecular force (or interaction). Compared to Ionic and Covalent bonds, H-bonding is very weak, but it is definitely stronger than Dipole-Dipole.
by Hannah Yates 1K
Sun Nov 04, 2018 6:12 pm
Forum: Lewis Structures
Topic: Exceptions to the Octet Rule
Replies: 4
Views: 57

Re: Exceptions to the Octet Rule

Any atom in the 3 orbital or lower can have an expanded octet. It is very common to see it on S, P, and Cl. A good example is PCl5. Phosphorus has an expanded octet with all 5 chlorine’s bonded to it.
by Hannah Yates 1K
Sun Nov 04, 2018 5:59 pm
Forum: Quantum Numbers and The H-Atom
Topic: Spin Magnetic Quantum Number
Replies: 6
Views: 330

Re: Spin Magnetic Quantum Number

505168807 wrote:Is there a possible way to determine whether the spin is +1/2 or -1/2?


No, I dont think that there is any way determine this, and if there is, we haven’t learned it.
by Hannah Yates 1K
Sun Nov 04, 2018 5:57 pm
Forum: Trends in The Periodic Table
Topic: Effective Nuclear Charge
Replies: 5
Views: 120

Re: Effective Nuclear Charge

Effective Nuclear Charge increases when the number of protons increases, and the number of protons increases as you go across a table
by Hannah Yates 1K
Sun Oct 28, 2018 4:05 pm
Forum: Administrative Questions and Class Announcements
Topic: Grading
Replies: 3
Views: 116

Grading

I had a few questions about the grading of this course. 1) how do I check my grade? 2) Is their any curve applied to the Tests? And 3) Is their any way to make up points lost on Tests?
by Hannah Yates 1K
Sun Oct 28, 2018 4:02 pm
Forum: Quantum Numbers and The H-Atom
Topic: The values of L and ML
Replies: 3
Views: 112

Re: The values of L and ML

L just refers to what sub shell the electron is in. The point of L=n-1 is to show the max value of L that it could be. So the value of L is not always going to be n-1.
by Hannah Yates 1K
Sun Oct 28, 2018 3:50 pm
Forum: Trends in The Periodic Table
Topic: Transition metal question
Replies: 3
Views: 84

Re: Transition metal question

there’s no rule that I know of, but I do know that when we do nomenclature of molecules, the name gives the number of valence electrons that the atom is loosing. For example, Copper (II) Oxide is the nomenclature for CuO. The nomenclature gives that Copper looses 2 electron.
by Hannah Yates 1K
Sat Oct 20, 2018 1:54 pm
Forum: Properties of Light
Topic: Grades
Replies: 7
Views: 141

Grades

This question isn’t related to properties of light but I didn’t know where to put it. Does anyone know where to go to check our grades in the class?
by Hannah Yates 1K
Sat Oct 20, 2018 1:49 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: H bar
Replies: 5
Views: 90

Re: H bar

H bar will not be given, which just means you need to do one more step when using Heisenberg indeterminacy equation. But, h will definitely be given.
by Hannah Yates 1K
Sat Oct 20, 2018 1:47 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: energy emission
Replies: 1
Views: 47

Re: energy emission

When electromagnetic radiation is emitted from an atom, I believe it means that the electron is dropping from a high energy level, to a low energy level. This means that the statement is false because when an electron does make that drop, energy is being emitted from the atom, therefor it is loosing...
by Hannah Yates 1K
Sat Oct 20, 2018 1:32 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Shielding [ENDORSED]
Replies: 14
Views: 548

Re: Shielding [ENDORSED]

Technically the 2s and 2p are the same orbital, but they have different suborbital. S is the closest suborbital to the nucleus, then P, then D, and so on.
by Hannah Yates 1K
Sun Oct 14, 2018 2:55 pm
Forum: DeBroglie Equation
Topic: "Wave-like Properties" of Matter
Replies: 6
Views: 79

Re: "Wave-like Properties" of Matter

The reason he gave us something with an unmeasurable wavelike property is so that we could understand that no matter what the velocity of that object is, if the mass is too big, it wont act like a wave. Like he said, a baseball, no matter how fast it is traveling, will never act like a wave. Only sm...
by Hannah Yates 1K
Sun Oct 14, 2018 2:48 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 4
Views: 68

Re: Work Function

In order to find the velocity, you would need the Energy of the ejected election. That means that you would either need the given the energy of the ejected electron or have a way to calculate it with the given information using the equation E(photon) - Threshold energy = E(electron).
by Hannah Yates 1K
Sun Oct 14, 2018 2:43 pm
Forum: Properties of Light
Topic: Rydberg Equation
Replies: 3
Views: 45

Re: Rydberg Equation

He basically said that it could be used but he doesn’t recommend it. I learned it in high school and it always confused me (even thought it is just plugging numbers into an equation). I didnt get it because I didnt get the basic understanding of what was happening. The way Levelle teaches this secti...
by Hannah Yates 1K
Sun Oct 07, 2018 6:23 pm
Forum: Balancing Chemical Reactions
Topic: States of Matter
Replies: 11
Views: 221

Re: States of Matter

I have always struggled on knowing the state of a given molecule so I am hoping that they will be given until we go over it in class.

As far as if it affects calculations, it doesn’t. All it does is help us visualize the reaction.
by Hannah Yates 1K
Sun Oct 07, 2018 6:20 pm
Forum: Balancing Chemical Reactions
Topic: Balancing reactions tips
Replies: 29
Views: 787

Re: Balancing reactions tips

I don’t know if this will help anyone, but every time I balance a combustion reaction, I am always thinking in even numbers. The reason for this is that if there is an odd number of oxygen on the product side of the reaction, the coefficient will end up being a number and a half. If I am always thin...
by Hannah Yates 1K
Sun Oct 07, 2018 6:12 pm
Forum: Significant Figures
Topic: Rounding numbers ending in 5
Replies: 9
Views: 131

Re: Rounding numbers ending in 5

I have once been told that if the number were something like 2.652 and I had to round to the 1st decimal place, it would be rounded to 2.6, but I have never really payed attention to that rule. Typically, I would still round to 2.7.

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