## Search found 103 matches

Fri Mar 13, 2020 7:45 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: what does it mean when kinetics rather than thermodynamics is controlling a reaction
Replies: 2
Views: 74

### Re: what does it mean when kinetics rather than thermodynamics is controlling a reaction

Thermodynamics typically deals with state functions whereas kinetics deals with different pathways that control the speed of the reaction. This especially comes into play when dealing with activation energies
Fri Mar 13, 2020 6:28 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Arrhenius Equation
Replies: 8
Views: 120

### Re: Arrhenius Equation

k=A*e^-Ea/RT This formula helps determine the temperature dependence of reaction rates. k is the reaction rate of the reaction. A is a pre-exponential factor and has to do with the collision of the molecule (and if it is properly oriented when it collides in order to react) Ea is the activation ene...
Fri Mar 13, 2020 6:20 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Test 2
Replies: 4
Views: 111

### Re: Test 2

Is the mailroom open on saturdays?
Fri Mar 13, 2020 6:12 pm
Forum: Ideal Gases
Topic: When to use equation
Replies: 9
Views: 199

### Re: When to use equation

If you need a value for an letter that is in the law, you can almost always use the law
Fri Mar 13, 2020 3:40 pm
Forum: Second Order Reactions
Topic: second order relation to second order integrated law
Replies: 4
Views: 92

### Re: second order relation to second order integrated law

If the second order rate is integrated, you end up with the second order rate law using a little calculus and algebra. The +C usually associated with an indefinite integral is represented in the integrated rate law by the initial concentration.
Fri Mar 13, 2020 3:35 pm
Forum: Biological Examples
Topic: ATP example
Replies: 6
Views: 778

### Re: ATP example

ATP happens to be a very unstable molecule due to its phosphate groups being next to each other (these phosphates all have negative charges) Thus when hydrolysis occurs, the products are at a lower energy state because they are more stable apart than together.
Fri Mar 13, 2020 3:32 pm
Forum: Experimental Details
Topic: Collision Theory
Replies: 8
Views: 533

### Re: Collision Theory

You should probably know that collisions need to have the appropriate amount of energy to break a bond and also be correctly oriented in order for a new molecule to form.
Fri Mar 13, 2020 3:31 pm
Forum: Environment, Ozone, CFCs
Topic: stoichiometric coefficients
Replies: 9
Views: 125

### Re: stoichiometric coefficients

Using a fraction is useful if you only want the product to have 1 mol in your equations.
Fri Mar 13, 2020 3:19 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure Rule
Replies: 4
Views: 90

### Re: Pressure Rule

Only pay attention to gases because they can be compressed.
Fri Mar 13, 2020 3:13 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: applications
Replies: 1
Views: 92

### applications

How are the Gibbs free energy equations used in biology?
Fri Mar 13, 2020 3:09 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Identification
Replies: 4
Views: 112

### Identification

How can you identify the pure form of an element?
Fri Mar 13, 2020 3:06 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: U vs H
Replies: 15
Views: 315

### Re: U vs H

delta U is change in internal energy whereas delta H is change in enthalpy.
Fri Mar 13, 2020 2:58 pm
Forum: Van't Hoff Equation
Topic: When to use
Replies: 5
Views: 140

### Re: When to use

You can use it when you can assume that delta H and delta S are the same at both temps.
Fri Mar 13, 2020 2:54 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed Systems
Replies: 14
Views: 236

### Re: Closed Systems

A closed system means that the system is closed off from exchanging mass with its surroundings but it can exchange energy. An isolated system cannot exchange either. Energy can be introduced into a closed system either through heat or work (increasing pressure).
Fri Mar 13, 2020 2:43 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Midterm question Q3B
Replies: 3
Views: 142

### Re: Midterm question Q3B

I think since B had the least amount of water, it was able to heat up the most since it didn't have to heat a larger amount of water (which has a high heat capacity)
Fri Mar 13, 2020 2:21 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: real world application?
Replies: 1
Views: 23

### real world application?

Are there any real world applications of the Nernst Equation not mentioned in class?
Fri Mar 13, 2020 2:19 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: electrode
Replies: 2
Views: 40

### electrode

What impact does the mass of an electrode have on the cell potential?
Fri Mar 13, 2020 2:15 pm
Forum: Zero Order Reactions
Topic: catalyst
Replies: 5
Views: 105

### Re: catalyst

Selena Yu 1H wrote:No, not all zero order reactions is dependent on a catalyst. A zero order reaction could also occur with an enzyme or a surface. It's just that most commonly you would find a catalyst with a zero order reaction.

Aren't enzymes just biological catalysts?
Fri Mar 13, 2020 2:10 pm
Forum: First Order Reactions
Topic: size
Replies: 6
Views: 143

### size

Does the size of the reactant influence the rate? I.E. is a bigger molecule consumed at a faster rate than say a hydrogen atom?
Fri Mar 13, 2020 1:57 pm
Forum: Zero Order Reactions
Topic: catalyst
Replies: 5
Views: 105

### catalyst

Are all zero order reactions dependent on a catalyst?
Fri Mar 13, 2020 1:51 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Slow step
Replies: 7
Views: 125

### Slow step

How slow does the slowest step need to be in order to be considered the slowest step? In other words is there a real time value?
Fri Mar 13, 2020 1:28 pm
Forum: General Rate Laws
Topic: Determining a rate law graphically
Replies: 1
Views: 31

### Determining a rate law graphically

Is it possible to determine a rate law from a tangent line or a secant line of a graph of time in seconds vs concentrations?
Fri Mar 13, 2020 1:21 pm
Forum: Administrative Questions and Class Announcements
Topic: Excellence in Chemistry Award!
Replies: 27
Views: 6840

### Re: Excellence in Chemistry Award!

Congrats!
Tue Mar 03, 2020 9:37 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Metal as solute
Replies: 2
Views: 81

### Metal as solute

How can you predict if a metal will dissolve in solution? Is it solely dependent on potential?
Sun Feb 16, 2020 10:59 pm
Forum: Van't Hoff Equation
Topic: Equilibrium Constant
Replies: 4
Views: 75

### Re: Equilibrium Constant

At equilibrium, delta g is zero, so that means we can use algebra to move it to the other side.
Sun Feb 16, 2020 10:49 pm
Forum: Van't Hoff Equation
Topic: Assumptions
Replies: 3
Views: 55

### Assumptions

When can we assume that delta entropy would be the same for different temperatures. Do the temperatures have to be close together?
Sun Feb 09, 2020 9:48 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Difference between Cv and Cp?
Replies: 8
Views: 87

### Re: Difference between Cv and Cp?

For ideal gases, Cp = Cv + R. The actual value of Cv will differ depending on whether it is monoatomic, linear (diatomic), and nonlinear.
Sun Feb 09, 2020 9:31 pm
Forum: Calculating Work of Expansion
Topic: Vacuum
Replies: 3
Views: 43

### Vacuum

What keywords will be given to indicate that the a system has no external pressure acting on it such as in a vacuum?
Sun Feb 09, 2020 9:21 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Law of Conservation Energy
Replies: 5
Views: 39

### Re: Law of Conservation Energy

This law is applied to isolated systems, but since the universe is basically an isolated system, it applies to the whole universe as well.
Sun Feb 09, 2020 9:11 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: ∆S for summation
Replies: 3
Views: 42

### Re: ∆S for summation

∆S for the products and reactants can be ignored because the function: ∆Sºrxn=∑Sºm(products)-∑Sºm(reactants) is only dependent on the actual values of the molar entropies not changes in the molar entropies.
Sun Feb 09, 2020 9:06 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 5
Views: 61

### Re: Gibbs Free Energy

905289082 wrote:When calculating Gibbs free energy, do you use the same method as you would for Hess's law?

The method shown in Hess's Law can really be extrapolated to all state functions.
Sun Feb 02, 2020 8:39 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Three Methods
Replies: 3
Views: 67

### Re: Three Methods

If a problem explicitly tells you the reaction enthalpies you'll probably use method 1 to find net rxn enthalpy. If you have a table of bond enthalpies you'll probably use method 2. If you have standard reaction enthalpies you'll use method 2 or 3. You might even use some sort of combination of thes...
Sun Feb 02, 2020 8:18 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Constant pressure
Replies: 2
Views: 36

### Re: Constant pressure

certain key phrases give away that a system is under constant pressure such as "open beaker". This is because you can assume that an open beaker has the external pressure of the atmosphere as a constant acting on it.
Sun Feb 02, 2020 8:15 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Method 2
Replies: 2
Views: 58

### Re: Method 2

You can assume all bonds are broken and reformed from the reactants to the products stage to be on the safe side since they cancel out if you do the calculations right. However if you know which bonds are broken and formed, it can save you some time and effort when doing your calculations.
Sun Feb 02, 2020 7:54 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: deltaU and deltaH
Replies: 4
Views: 45

### Re: deltaU and deltaH

delta H corresponds to gases more because solids and liquids do not change a significant enough amount in volume.
Sun Feb 02, 2020 7:46 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: using mass in calorimeter
Replies: 3
Views: 49

### Re: using mass in calorimeter

mass is used directly for specific heat capacities and can be used indirectly for molar heat capacities
Sun Jan 26, 2020 8:41 pm
Forum: Phase Changes & Related Calculations
Topic: Why does steam cause burns?
Replies: 29
Views: 272

### Re: Why does steam cause burns?

Steam is worse than water even at the same temperature when coming into contact with your skin. This is because the steam has much higher enthalpy than the water, even if they are at the same temperature. Once the steam comes into contact with your skin, it condenses and this phase change releases m...
Sun Jan 26, 2020 8:27 pm
Forum: Phase Changes & Related Calculations
Topic: phase changes
Replies: 2
Views: 48

### Re: phase changes

If you're trying to incorporate a phase change into your calculation, you must take into which phase change it is. The increase in enthalpy needed to melt ice, is different from the increase in enthalpy needed to boil water. Once you know what kind of phase change you're dealing with, include it in ...
Sun Jan 26, 2020 8:21 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy is said to be additive
Replies: 10
Views: 114

### Re: Enthalpy is said to be additive

Because Enthalpy is a state function, only the state matters. In other words, what matters is the state, not the way that those states were obtained or the path that led them there. This is what allows enthalpy to be additive.
Sun Jan 26, 2020 6:53 pm
Forum: Phase Changes & Related Calculations
Topic: State function
Replies: 4
Views: 33

### State function

Why isn't heat a state function but enthalpy is?
Sun Jan 26, 2020 4:45 pm
Forum: Phase Changes & Related Calculations
Topic: phase changes
Replies: 6
Views: 58

### Re: phase changes

since phase changes can be either exothermic or endothermic, they should be taken into account when calculating changes in enthalpy.
Sun Jan 19, 2020 7:26 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pH vs. pOH
Replies: 13
Views: 142

### Re: pH vs. pOH

To calculate pOH it is simply =-log[OH-] , and to find pH it is -log[H+] or -log[H30+]. pOH is used to calculate the strength of bases, while pH is used to calculate the strength of acids. To find one if the other is given the equation is pH+pOH=14.
Sun Jan 19, 2020 7:07 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: 5% rule
Replies: 10
Views: 125

### Re: 5% rule

The 5% rule is sort of like checking your work. If you approximated by ignoring x, if the percent ionization was less than 5%, then the approximation was fine.
Sun Jan 19, 2020 6:26 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: X was ignored
Replies: 27
Views: 226

### Re: X was ignored

If you are unsure about the cutoff for ignoring X, you can generally ignore if K is less than 10^-3 but you can always ignore if less than 10^-5.
Sun Jan 19, 2020 6:18 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Temperature
Replies: 5
Views: 46

### Re: Temperature

If a reaction is exothermic, increasing the temperature will shift the reaction towards the reactants. If a reaction is endothermic, increasing the temperature will shift the reaction towards the products. Decreasing the temperature will shift the reaction towards exothermic products.
Sun Jan 19, 2020 6:10 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Endo vs. Exothermic
Replies: 5
Views: 44

### Re: Endo vs. Exothermic

If a reaction is exothermic, it releases energy. If a reaction is endothermic, it absorbs energy.
Sun Jan 12, 2020 10:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentration affecting equilibrium
Replies: 5
Views: 60

### Re: Concentration affecting equilibrium

Changing the concentrations does not change the K value. However, in the short term it will change the value of Q. Adding more products will make the value of Q larger and if Q>K then the system will favor the formation of reactants and vice versa.
Sun Jan 12, 2020 10:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q
Replies: 10
Views: 112

### Re: Q

Its useful to predict the direction of a reaction since you can find Q even if the system is not at equilibrium. If K is known, and you can measure Q, then you determine which side a reaction will favor until it reaches equilibrium. If Q<K, then the reaction will favor products until K is reached. I...
Sun Jan 12, 2020 10:02 pm
Forum: Ideal Gases
Topic: partial pressures
Replies: 7
Views: 76

### Re: partial pressures

A change to concentrations does not change the equilibrium constant. That is why K remains the same even when concentrations increase or decrease. What should be noted is that K is only for reactions at equilibrium, what that means is that if you add or take away products or reactants and therefore ...
Sun Jan 12, 2020 9:43 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K (eq constant) vs k (rate constant)?
Replies: 3
Views: 38

### Re: K (eq constant) vs k (rate constant)?

At equilibrium, the rate of product formation and the rate of reactant formation cancel out but do not necessarily stop. This is what is meant by the saying "all chemical equilibria are dynamic" . K is a ratio of activity that is why pressure and concentration can both be used.
Sun Jan 12, 2020 9:27 pm
Forum: Ideal Gases
Topic: Ideal gas law exceptions
Replies: 3
Views: 38

### Re: Ideal gas law exceptions

For the most part, noble gases conform to the ideal gas law but the law is an approximation so make sure to keep that in mind when using it for all gases.
Fri Dec 06, 2019 12:55 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B1
Replies: 2
Views: 53

### Re: 6B1

Find the pH of the first value, then subtract it from the second pH value. To find the second pH value simply multiply the first concentration by (V1/V2) inside the -log.
Fri Dec 06, 2019 12:46 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strong vs. weak acids and bases
Replies: 3
Views: 49

### Re: Strong vs. weak acids and bases

for a given period, the strength of an acid (specifically of an element only bonded to hydrogen) increases as you go from left to right e.g. nitrogen to oxygen to fluorine. As you go down a group, the strength of an acid increases e.g. the halogens. HI>HBr>HCl>HF
Fri Dec 06, 2019 12:41 am
Forum: Amphoteric Compounds
Topic: As2O3
Replies: 3
Views: 128

### Re: As2O3

Arsenic forms salts with both acids and bases and that contributes to its amphoteric properties.
Thu Dec 05, 2019 11:33 pm
Forum: Bronsted Acids & Bases
Topic: Formic acid strength
Replies: 2
Views: 49

### Formic acid strength

Why is acetic acid weaker than formic acid?
Thu Dec 05, 2019 9:30 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: 6B.3 (b)
Replies: 3
Views: 80

### Re: 6B.3 (b)

For part b, is there a formula that tells us we can plug in the (200 x 0.025)/250 to the -log, or are we just doing the conversion to molarity using M1V1=M2V2 inside the pH=-log[H3O+] formula? I used the method of (200 x 0.025)/250 in the -log and received the correct answer. This is functionally t...
Sun Dec 01, 2019 9:07 pm
Forum: Bronsted Acids & Bases
Topic: Water as an acid and base
Replies: 7
Views: 112

### Re: Water as an acid and base

Water is amphoteric meaning it can react as an acid or base. While acting as a base it accepts a proton from an acid and becomes a hydronium ion. While acting as an acid, it donates a proton and then becomes a hydroxide ion.
Sun Dec 01, 2019 8:57 pm
Forum: Bronsted Acids & Bases
Topic: Lewis vs. Bronsted
Replies: 3
Views: 58

### Re: Lewis vs. Bronsted

A Lewis acid is defined as accepting an electron pair while a bronsted acid is defined as donating a proton. A lewis base is defined as donating an electron pair while a bronsted base is deifned as accepting a proton. Note that in water, the "proton" defers to a hydronium ion such as in th...
Sun Dec 01, 2019 7:19 pm
Forum: Bronsted Acids & Bases
Topic: Conjugate acids and bases
Replies: 5
Views: 101

### Re: Conjugate acids and bases

Sidenote: conjugate acids/bases will generally be weaker than their original, strong corresponding acids/bases
Sun Dec 01, 2019 7:15 pm
Forum: Bronsted Acids & Bases
Topic: Difference between Arrhenius, Bronsted, and Lewis Acids/Bases
Replies: 2
Views: 59

### Re: Difference between Arrhenius, Bronsted, and Lewis Acids/Bases

Arrhenius is a little more specified towards aqueous solutions, which is why the bronsted definition is used more generally.
Sun Nov 24, 2019 2:37 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Identifying Polydentate Ligands
Replies: 5
Views: 49

### Re: Identifying Polydentate Ligands

typically, a polydentate will only a polyatomic sepcies since a single atom or ion would be too small to take more than one "bite"
Sun Nov 24, 2019 2:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 9C. 7
Replies: 2
Views: 55

### Re: 9C. 7

Only b can form a chelating compound because only there are the NH2 groups close enough to bind to the same atom
Sun Nov 24, 2019 1:59 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 2
Views: 43

### Re: Coordination Number

coordination number is determined by the number of bonds to the metal atom
Sun Nov 24, 2019 1:36 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Transition Metals
Replies: 3
Views: 54

### Re: Transition Metals

Transition are also favored for coordination compounds because they often appear as cations.
Sun Nov 24, 2019 1:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxidation states
Replies: 6
Views: 68

### Re: Oxidation states

oxidation state is more related to the cation before it bonded whereas formal charge is determined in bonds.
Sat Nov 23, 2019 9:30 pm
Forum: Naming
Topic: Naming order
Replies: 2
Views: 51

### Re: Naming order

IIRC he said something about naming the ligands alphabetically but ignoring the greek prefixes
Sun Nov 17, 2019 10:29 pm
Forum: Electronegativity
Topic: Atom size
Replies: 22
Views: 717

### Re: Atom size

On the periodic table, the further you go down and to the left, the larger the size of the atom. In terms of periods, size decreases from left to right. In terms of groups, size increases as you go down.
Sun Nov 17, 2019 10:15 pm
Forum: Lewis Structures
Topic: Why can Xenon break the octet rule?
Replies: 8
Views: 580

### Re: Why can Xenon break the octet rule?

In the typical example of xenon tetrafluoride, Xenon has 4 bonds and two lone pairs. This is possible since xenon is a large atom with valence electrons far away from its nucleus (relative to the noble gases that precede it) and fluorine is electronegative enough to pull away Xenons valence electron...
Sun Nov 17, 2019 8:52 pm
Forum: Electronegativity
Topic: More electronegative?
Replies: 3
Views: 135

### Re: More electronegative?

IIRC Oxygen is the second most electronegative element, second only to Fluorine. When both of these elements fill their valence they have the very stable configuration of neon. While Chlorine is closer to filling its octet than oxygen is, its valence electrons are also farther from its nucleus than ...
Sun Nov 17, 2019 8:28 pm
Forum: Sigma & Pi Bonds
Topic: Sigma vs Pi
Replies: 11
Views: 226

### Re: Sigma vs Pi

All single covalent bonds are sigma bonds. Double bonds include one sigma and one pi bond. Triple bonds include one sigma bond and two pi bonds.
Sun Nov 17, 2019 8:08 pm
Forum: Ionic & Covalent Bonds
Topic: Strength and Length
Replies: 18
Views: 237

### Re: Strength and Length

Put simply, the shorter a bond is, the stronger it is, and vice versa. To understand why this happens you need to consider the electron clouds of atoms. If the electron clouds of two atoms overlap, the bond will be stronger and also shorter. More overlapping is associated with stronger bonds and sho...
Sun Nov 10, 2019 8:07 pm
Forum: Dipole Moments
Topic: Identifying dipoles
Replies: 3
Views: 50

### Identifying dipoles

Can you identify a dipole moment by analyzing its Lewis structure and formal charge or must you also consider electronegativity
Tue Nov 05, 2019 11:35 pm
Forum: Properties of Light
Topic: Wavelength and Type of Light
Replies: 3
Views: 120

### Re: Wavelength and Type of Light

You should know the range in nm for visible light (700-400) and also the colors associated with each end of the spectrum (red for values closer to 700nm and violet for values closer to 400nm). As for the other ranges on the electromagnetic spectrum, you should generally know the order of EM radiatio...
Tue Nov 05, 2019 11:28 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: +- vs Uncertainty
Replies: 3
Views: 161

### Re: +- vs Uncertainty

For a value like "32+-0.25 meters" you multiply the +- value by two to represent the total range in uncertainty of the value. The same logic applies if you are given the radius as a possible range of position for an electron to occupy. Since you want to represent the total range of uncerta...
Tue Nov 05, 2019 11:21 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect vs. De Broglie
Replies: 8
Views: 304

### Re: Photoelectric Effect vs. De Broglie

The speed of light equation can only be used for Electromagnetic radiation since that equation, c=vλ is based on the propagation wave speed formula for values specific to light. The De Broglie equation is used for particles with momentum which means it is used for particles with mass, e.g. electrons...
Tue Nov 05, 2019 11:08 pm
Forum: Einstein Equation
Topic: e=hv used for particles?
Replies: 9
Views: 216

### Re: e=hv used for particles?

E=hv can only be used for Electromagnetic radiation (light). To find the energy for other particles, use the kinetic energy equation: KE=(1/2)mv^2 since other particles have mass. If you want to find the wavelength for light, use λ=c/v; for particles with mass use the De Broglie equation: λ=h/p
Tue Nov 05, 2019 10:54 pm
Forum: DeBroglie Equation
Topic: Do neutrons have diffraction patterns?
Replies: 2
Views: 132

### Re: Do neutrons have diffraction patterns?

Neutrons do have diffraction patterns; the De Broglie equation can be used for any object with momentum but observable wavelengths are only really present when a particle has very small mass such as electrons, neutrons, and protons. Objects on the scale of paperclips and cars have masses so great th...
Sat Nov 02, 2019 9:53 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8200
Views: 1432130

### Re: Post All Chemistry Jokes Here

nice joke,
Helium Helium Helium
Sat Nov 02, 2019 9:23 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: isoelectronic definition
Replies: 7
Views: 99

### isoelectronic definition

Does being isoelectronic mean having the same number of electrons or having the same electron configuration?
Sat Nov 02, 2019 8:42 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: using indeterminancy
Replies: 3
Views: 81

### using indeterminancy

If a speed is given such as 58 +-3 m/s is stated as the speed for a particle, does 3 need to always be multiplied by 2 in order to find the indeterminacy of a delta?
Sat Nov 02, 2019 8:15 pm
Forum: Properties of Light
Topic: Hz vs. frequency
Replies: 7
Views: 241

### Re: Hz vs. frequency

When dealing with frequency, the unit needed for equations is Hz(s^-1), also the name of the greek letter is nu, not "v" since that would be confused too easily with velocity
Sat Nov 02, 2019 8:05 pm
Forum: Molarity, Solutions, Dilutions
Topic: initial and final variables
Replies: 4
Views: 199

### initial and final variables

Is there an easy way to identify which volumes and molarities are first and second, or is it just a matter of reading the question very carefully?
Sat Nov 02, 2019 7:58 pm
Forum: Octet Exceptions
Topic: p-block elements
Replies: 2
Views: 47

### Re: p-block elements

is the limit of valence electrons the same for all these 3rd period nonmetals or does it vary atom by atom?
Sat Nov 02, 2019 7:56 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Cu and Cr
Replies: 11
Views: 103

### Re: Cu and Cr

So this means that this trend would also apply to silver as it applies to copper?
Sat Nov 02, 2019 7:52 pm
Forum: Bond Lengths & Energies
Topic: bond length
Replies: 6
Views: 90

### bond length

Is it possible to find the length of a bond based on its strength or vice versa?
Sat Nov 02, 2019 7:43 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: periodic trends
Replies: 2
Views: 67

### periodic trends

Is there a periodic trend for polarizing power?
Sat Nov 02, 2019 7:38 pm
Forum: Octet Exceptions
Topic: p-block elements
Replies: 2
Views: 47

### p-block elements

Why are the p-block nonmetals in the 3rd period exceptions to the octet rule but the p-block nonmetals in the 2nd period are not?
Sat Nov 02, 2019 7:34 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal charge equation
Replies: 3
Views: 47

### Formal charge equation

Can the equation for formal charge be rewritten as Valence electrons - (dots + lines)= formal charge?
Sun Oct 20, 2019 10:26 pm
Forum: Quantum Numbers and The H-Atom
Topic: electron spin
Replies: 4
Views: 89

### electron spin

How can spin be visualized when thinking of electrons as waves and particles?
Sun Oct 20, 2019 10:02 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8200
Views: 1432130

### Re: Post All Chemistry Jokes Here

Using E=hv to find the frequency?

Nah bro, just Einstein checking your vibes
Sun Oct 20, 2019 7:57 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Advice for studying
Replies: 92
Views: 1929

### Re: Advice for studying

The video modules on the Chem 14A website are excellent resource for initially learning, but to solidify information for long-term recall, forming a study group to do practice problems/tests is a really solid strategy.
Sun Oct 20, 2019 7:46 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: h bar formula [ENDORSED]
Replies: 4
Views: 94

### Re: h bar formula[ENDORSED]

Since h bar is equal to (h/2π) it's very useful as shorthand where this value is used often like in Heisenberg indeterminacy equation and the Schrodinger equation. In the Heisenberg equation, the (h-bar/2) is equal to (h/4π) in case you come across the equation using h-bar.
Sun Oct 20, 2019 7:30 pm
Forum: *Shrodinger Equation
Topic: Schrodinger for exam
Replies: 20
Views: 436

### Re: Schrodinger for exam

Understanding the equation at conceptual level is important but understanding the finer details of the equation is not as important for this level of chemistry
Sun Oct 13, 2019 2:08 pm
Forum: Properties of Light
Topic: Light intensity and Kinetic Energy
Replies: 7
Views: 119

### Re: Light intensity and Kinetic Energy

When thinking about the energy of light, it's more useful to think about light as photons instead of waves. Intensity in terms of photons just refers to the amount of photons present. A higher intensity means more photons. The equations relating to the energy of light, E=hv, is specifically for one ...
Sun Oct 13, 2019 1:38 pm
Forum: Properties of Light
Topic: 1A3
Replies: 5
Views: 67

### Re: 1A3

the speed of light, 3.0x10^8 m/s, remains the same for all EM radiation no matter the frequency or wavelength.
Sun Oct 13, 2019 1:21 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Rydberg equation [ENDORSED]
Replies: 73
Views: 3939

### Re: Rydberg equation[ENDORSED]

The rydberg constant is 3.29x10^15 hz when solving for frequency while in other equations it appears as 1.097x10^-7m in other equations. It's important to use the right version of the constant depending on what you are solving for.
Sun Oct 13, 2019 12:54 pm
Forum: Limiting Reactant Calculations
Topic: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
Replies: 68
Views: 3970

### Re: Showing Work for Limiting Reactant Calculations on Tests[ENDORSED]

When showing work it's important to include the right units in your work.
Sun Oct 13, 2019 12:39 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Test 1 [ENDORSED]
Replies: 107
Views: 5192

### Re: Test 1[ENDORSED]

Test 1 and 2 are both 50 points each and both have 50 minute time limits.
Thu Oct 03, 2019 8:21 pm
Forum: Einstein Equation
Topic: de brogile equation
Replies: 6
Views: 745

### Re: de brogile equation

When dealing with Electromagnetic radiation (light) its useful to use the light equations : E=hν and c=λν, but keep in mind that these equations are specific to EM radiation. This is where De broglie's equation comes into play when dealing with the other particles (that have mass). De broglie's equa...
Thu Oct 03, 2019 7:44 pm
Forum: Properties of Light
Topic: EM Spectrum
Replies: 4
Views: 90

### Re: EM Spectrum

You will most likely need to understand the relationship between each wavelength range (radio, microwave, infrared, visible light, UV, X-ray, and gamma) and their respective frequencies as it relates to the energy of each segment of the spectrum.

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