## Search found 60 matches

Fri Mar 15, 2019 9:34 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Effects of Temperature on Rate Constant
Replies: 1
Views: 139

### Effects of Temperature on Rate Constant

Why does raising the temperature increases the rate constant of reactions with higher activation barriers more than it does the rate constant of reactions with lower activation barriers?
Fri Mar 15, 2019 9:34 pm
Forum: Second Order Reactions
Topic: Non-integer orders
Replies: 7
Views: 420

### Non-integer orders

Will we ever be expected to know/find non-integer (like 1.5) reactant orders?
Fri Mar 15, 2019 9:33 pm
Forum: Second Order Reactions
Topic: Half-life of Second-Order
Replies: 4
Views: 327

### Half-life of Second-Order

In the textbook, at the end of section 15.6, it gives a table detailing all the components of each order of a reaction. For the half-life of a second-order reaction, it writes that the equation is t1/2=. However, underneath that, it says "(not used)." Does anyone know what this means/why t...
Sun Mar 10, 2019 4:59 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Steady State or Pre-Equilibrium approach
Replies: 1
Views: 92

### Steady State or Pre-Equilibrium approach

Do we have to learn the steady state approach in the book or should we just study pre-equilibrium one he taught us in lecture?
Sun Mar 10, 2019 4:59 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Rate Determining Step
Replies: 1
Views: 102

### Rate Determining Step

Will the problems always state which step is fast and slow so that we could determine the rate determining step or do we have to some how figure it out based on the context given?
Sun Mar 10, 2019 4:58 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Reaction Profiles
Replies: 2
Views: 135

### Reaction Profiles

How can we tell from a reaction profile whether a reaction is spontaneous? I understand that it must be energetically favorable, but at what point is the activation energy low enough? Do we just assume that it is low enough when the hump is relatively low?
Sun Mar 03, 2019 10:05 pm
Forum: General Rate Laws
Topic: 2nd order Integrated Rate Law Graph
Replies: 1
Views: 83

### 2nd order Integrated Rate Law Graph

What are the axises for the 2nd order Integrated Rate Law Graph? I know that the first order rate law graph is ln[A] vs. time.
Sun Mar 03, 2019 10:04 pm
Forum: General Rate Laws
Topic: General Rate Law Orders
Replies: 3
Views: 159

### General Rate Law Orders

How does one know whether a reaction is first order or second order using the graph?
Sun Mar 03, 2019 10:04 pm
Forum: General Rate Laws
Topic: Unique Average Rate versus Average Rate
Replies: 1
Views: 103

### Unique Average Rate versus Average Rate

When we're asked to find the rate of consumption or rate of formation of a molecule in a reaction, when is it necessary to divide (change in concentration)/(change in time) by the number of moles of that molecule?]
Sat Feb 23, 2019 3:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Order of species in cell diagram
Replies: 1
Views: 100

### Order of species in cell diagram

I understand that for a cell diagram, the anode is on the left, the cathode is on the right, and the electrodes are at the ends... but within the anode or cathode, does it matter what order you write the species in?
Sat Feb 23, 2019 3:35 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 2
Views: 116

### Salt Bridge

How does a salt bridge work? The textbook says that its to prevent contact between the two aqueous solutions because when different ions mingle they can affect the cell potential but its function is described as "allowing the flow of ions" wouldn't this mean its letting them meet?
Sat Feb 23, 2019 3:34 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Potential Calculation
Replies: 1
Views: 77

### Cell Potential Calculation

Why do we subtract anode from cathode from in order to calculate the cell potential?
Sun Feb 17, 2019 9:13 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Two Gibbs Free Energy Formulas
Replies: 2
Views: 124

### Two Gibbs Free Energy Formulas

While the two Gibbs Free Energy formulas are both applicable, how do we distinguish when to use which? For example, if given the concentrations of the products and the reactants, will we then use the deltaG=-RTlnK?
Sun Feb 17, 2019 9:12 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free energy and spontaneity
Replies: 2
Views: 83

### Gibbs Free energy and spontaneity

Why is it that when Gibbs free energy of the system is negative then the process is spontaneous and the delta S universal is positive? How does delta G being negative make the process spontaneous?
Sun Feb 17, 2019 9:12 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Determining Spontaneity
Replies: 1
Views: 102

### Determining Spontaneity

A system is spontaneous when Delta G is negative and also when Delta S total is positive. Why can't we tell the spontaneity of a system by looking at Delta H?
Sat Feb 09, 2019 10:34 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Units
Replies: 1
Views: 88

### Units

When calculating standard reaction enthalpy, entropy, and Gibbs free energy from formation values, why do the answers have units with /mol? Shouldn't /mol cancel out since you multiply by the coefficient in the calculation?
Sat Feb 09, 2019 10:32 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Changes in Entropy
Replies: 2
Views: 124

### Changes in Entropy

Is there a preferred way to describe a change in entropy of a system? Rather than just saying the amount of disorder within the system has increased or decreased how can we be more specific in this description?
Sat Feb 09, 2019 10:30 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Spontaneity
Replies: 2
Views: 112

### Spontaneity

If deltaH is positive and deltaS is negative, what is the spontaneity?
Sat Feb 02, 2019 9:09 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Reversible v irreversible
Replies: 4
Views: 190

### Reversible v irreversible

For entropy, which equations do you use for isothermal reversible vs. irreversible free expansion? What does free expansion mean?
Sat Feb 02, 2019 9:09 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy in Reversible Process
Replies: 2
Views: 118

### Entropy in Reversible Process

Why is the total entropy in the universe 0 (Entropy system = Entropy surroundings) for reversible processes?
Sat Feb 02, 2019 9:08 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy Equation Specific Heat Capacity
Replies: 2
Views: 124

### Entropy Equation Specific Heat Capacity

How do you know when to use 3/2 R instead of the specific heat capacity provided on the cover sheet?
Thu Jan 24, 2019 1:17 pm
Forum: Phase Changes & Related Calculations
Topic: Elements in different states
Replies: 2
Views: 126

### Elements in different states

Can all elements be converted into solid, liquid, or gas states given that the right amount of energy and pressure is applied?
Thu Jan 24, 2019 1:16 pm
Forum: Phase Changes & Related Calculations
Topic: Reversible and Irreversible Processes
Replies: 1
Views: 98

### Reversible and Irreversible Processes

Reversible and irreversible processes have different equations but what exactly is the difference between the processes? How can the differences be logically explained?
Thu Jan 24, 2019 1:14 pm
Forum: Phase Changes & Related Calculations
Topic: Temperature vs. heat vs. energy
Replies: 4
Views: 194

### Temperature vs. heat vs. energy

I get that temperature and heat are different things but how they are related. For example, does an increase in temperature always lead to an increase in heat content (or the other way around). Also is energy just another term for heat content?
Sat Jan 19, 2019 9:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Molar Concentration
Replies: 3
Views: 90

### Molar Concentration

If you are given a molar concentration for a molecule with a stoichiometric coefficient does that concentration need to be multiplied by the stoichiometric coefficient to find the concentration of the single molecule?
Sat Jan 19, 2019 9:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: X Value
Replies: 3
Views: 125

### X Value

I know that 10^-5 or lower is when we can disregard the x but if something is 10^-4, can we still disregard and just check that the x value divided by the initial concentration is less than 5%
Sat Jan 19, 2019 9:12 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentrations Effect on K
Replies: 8
Views: 221

### Concentrations Effect on K

If the concentration of each reactant and product increased by the same amount, would K also increase or would it stay the same since it is a ratio?
Sat Jan 12, 2019 6:15 pm
Forum: Ideal Gases
Topic: K and Q
Replies: 7
Views: 312

### K and Q

If Q and K both have the same formula why are they not equal to each other?
Sat Jan 12, 2019 6:13 pm
Forum: Ideal Gases
Topic: Concentration or Partial Pressure
Replies: 13
Views: 380

### Concentration or Partial Pressure

When do we use concentration to find the equilibrium constant and when do we use partial pressure to find equilibrium constant? Will the question ask for one of the two specifically?
Sat Jan 12, 2019 6:11 pm
Forum: Ideal Gases
Topic: bar or atm
Replies: 8
Views: 310

### bar or atm

In the textbook the units are in bars but in Lavelle's slides he uses atm. Would we need to know how convert between the two during tests or will the question give us the units?
Wed Dec 05, 2018 3:53 pm
Forum: Naming
Topic: Writing chemical formulas
Replies: 2
Views: 119

### Writing chemical formulas

When writing the chemical formula for water, would it matter if we use "H2O" or "OH2"?
Wed Dec 05, 2018 3:50 pm
Forum: Naming
Topic: Poly v Mono
Replies: 2
Views: 50

### Poly v Mono

What does it mean to have a poly- versus a mono-dentate compound and does it affect the naming of the compound?
Wed Dec 05, 2018 3:41 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pOH from pH
Replies: 2
Views: 163

### Re: pOH from pH

Yes. The pH + pOH = 14. The two expressions are opposites expressions. As the pH increases the pOH decreases and vice versa. Both values equal 14.
Sun Dec 02, 2018 2:51 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Final pH
Replies: 3
Views: 122

### Final pH

why do we subtract the pOH from 14 to find the final pH?
Sun Dec 02, 2018 2:48 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Negative pH?
Replies: 5
Views: 206

### Negative pH?

is it ever possible to get a negative pH? if so could someone explain how this could happen?
Sun Dec 02, 2018 2:45 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Sig Figs for pH and pOH calculations
Replies: 1
Views: 98

### Sig Figs for pH and pOH calculations

when we calculate the pH and pOH do we still take into account sig figs in the final answer?
Tue Nov 20, 2018 10:32 am
Forum: Hybridization
Topic: Bond Angles
Replies: 4
Views: 196

### Bond Angles

Is drawing the molecular shape of a molecule the only way to determine bond angles?
Tue Nov 20, 2018 10:30 am
Forum: Hybridization
Topic: d Orbital
Replies: 6
Views: 202

### d Orbital

Will we need to know how to draw d orbitals and know their shapes? I know that we need to know this for the s and p orbitals but I was wondering what exactly we need to focus on for the d orbitals.
Tue Nov 20, 2018 10:25 am
Forum: Hybridization
Topic: Pi and Sigma Bonds
Replies: 4
Views: 201

### Pi and Sigma Bonds

Whats the difference between pi and sigma bonds? And why can there be two pi bonds but not two sigma bonds?
Sat Nov 17, 2018 2:45 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Square Planar Angles
Replies: 3
Views: 168

### Square Planar Angles

In a molecule with a square planar structure will the angles between the remaining 4 bonded atoms remain 90 degrees? Or will the repulsion push them closer together?
Sat Nov 17, 2018 2:38 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Double and Triple Bonds
Replies: 2
Views: 109

### Double and Triple Bonds

In a double or triple bond why is the region of electron density equal one instead of two or three?
Sat Nov 17, 2018 2:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Chart
Replies: 3
Views: 173

### VSEPR Chart

I came across a VSEPR chart and thought I'd share it.
Sat Nov 10, 2018 9:50 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lewis Structures and VSEPR
Replies: 1
Views: 37

### Lewis Structures and VSEPR

Do we need to draw lewis structures in a way that reflects the molecular shape? Also for future tests would it matter where we draw the lone pair in lewis structures?
Sat Nov 10, 2018 9:43 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle
Replies: 2
Views: 46

### Bond Angle

If a trigonal pyramidal forms a coordinate covalent bond with its lone pair and its shape becomes a tetrahedral, would the bond angle become 109.5 degrees?
Sat Nov 10, 2018 9:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Two Central Atoms [ENDORSED]
Replies: 1
Views: 176

### Two Central Atoms[ENDORSED]

When there are two central atoms how would you name the lewis structure and use VSEPR to classify its shape?
Tue Oct 30, 2018 10:53 pm
Forum: Octet Exceptions
Topic: FC and Octet Exceptions
Replies: 1
Views: 111

### FC and Octet Exceptions

For different exceptions of the octet does the FC need to be fixed to zero or do the rules that the octet had overrule?
Tue Oct 30, 2018 10:51 pm
Forum: Formal Charge and Oxidation Numbers
Topic: FC in relation to Bonds
Replies: 2
Views: 93

### FC in relation to Bonds

How do single, double, and triple bonds affect formal charge?
Tue Oct 30, 2018 10:48 pm
Forum: Lewis Structures
Topic: Stable Lewis Structures
Replies: 4
Views: 132

### Stable Lewis Structures

When making Lewis Structures and deciding where to use double bonds how can we determine which version is more stable?
Thu Oct 25, 2018 7:45 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbital Shape for Larger Quantum Numbers
Replies: 3
Views: 155

### Orbital Shape for Larger Quantum Numbers

Does orbital f correspond to all values of n greater than or equal to four and all values of l greater than or equal to 3?
Thu Oct 25, 2018 7:38 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Ground state vs. excited state
Replies: 5
Views: 257

### Ground state vs. excited state

What does it mean for an electron configuration to represent a ground or excited state of an atom? Is it talking about the same/opposite spin?
Thu Oct 25, 2018 7:22 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Quantum Numbers n, l, and m
Replies: 5
Views: 187

### Quantum Numbers n, l, and m

Can the relationship between n, l, and m be described as shell, sub-shell, and orbital within a sub-shell, respectively? And does the value of l tell you the highest possible sub-shell of that particular energy level?
Wed Oct 17, 2018 7:37 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Px Py Pz
Replies: 1
Views: 44

### Px Py Pz

For exams how should we label electron configuration? For example, 2px^1 2py^2 2pz^3 is the same thing as 2p^3 so which format would be preferred on exams.
Wed Oct 17, 2018 7:25 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Shells, subshells, and orbital
Replies: 1
Views: 36

### Shells, subshells, and orbital

Whats the difference between shell, subshell, and an orbital? I've seen those terms being referred to in problems but I wasn't sure what the difference was between the three.
Wed Oct 17, 2018 7:18 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbitals
Replies: 1
Views: 42

### Orbitals

When writing the ground state of an element would it still be okay to order it as 4s2, 3d10 instead of 3d10, 4s2 even though 4s2 is filled in first. The answers to these problems are sometimes switched.
Sat Oct 13, 2018 6:26 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8475
Views: 1467036

### Re: Post All Chemistry Jokes Here

because all the good ones Argon.
Sat Oct 13, 2018 6:25 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8475
Views: 1467036

### Re: Post All Chemistry Jokes Here

Do you know any jokes about sodium hypobromite?

NaBrO.
Sat Oct 13, 2018 6:24 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8475
Views: 1467036

### Re: Post All Chemistry Jokes Here

What do you do with a sick chemist?

If you can't helium and you can't curium then you might as well barium!
Thu Oct 04, 2018 4:33 pm
Forum: Significant Figures
Topic: Sig Figs... when to round?
Replies: 7
Views: 335

### Re: Sig Figs... when to round?

For some of the homework problems I got answers that are off by a few numbers because of sig figs and rounding. Would my answers still be correct and what is the accepted range for the answers?
Thu Oct 04, 2018 3:06 pm
Forum: Significant Figures
Topic: All students read this sig fig post [ENDORSED]
Replies: 133
Views: 17918

### Re: All students read this sig fig post[ENDORSED]

When finding the molar mass in the periodic table how many sig figs do we use?
Thu Oct 04, 2018 2:59 pm
Forum: SI Units, Unit Conversions
Topic: How does grading for discussion posts work?
Replies: 80
Views: 4090

### Re: How does grading for discussion posts work?

Riley Dean 1D wrote:Does anyone know when the cutoff for week one's discussion period is? Like how long we have to post for week one and when week two starts?

I think the cutoff is on Fridays. So basically three posts by Friday week one, three posts by Friday week two, etc.