## Search found 56 matches

Mon Mar 11, 2019 4:05 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Large Ea
Replies: 2
Views: 80

### Large Ea

Is there ever an activation energy that is so large that the reaction can't proceed? What causes this/can this occur suddenly because of something in the reaction?
Mon Mar 11, 2019 4:03 pm
Forum: *Free Energy of Activation vs Activation Energy
Topic: Factors
Replies: 1
Views: 473

### Factors

What factors alter how large or small the activation energy of a reaction is?
Mon Mar 04, 2019 4:40 pm
Forum: General Rate Laws
Topic: Rate Law Formula
Replies: 2
Views: 120

### Rate Law Formula

Do these general rate laws work for every order of reaction? Are there any exceptions?
Mon Mar 04, 2019 4:37 pm
Forum: General Rate Laws
Topic: K
Replies: 3
Views: 136

### K

What factors of a reaction affect its K value?
Mon Mar 04, 2019 4:35 pm
Forum: Zero Order Reactions
Topic: Different Orders
Replies: 5
Views: 172

### Different Orders

Do we only have to know how to do 0-2nd order reaction calculations? And are the calculations similar or are they derived differently?
Mon Feb 25, 2019 4:07 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Standard Cell Potential [ENDORSED]
Replies: 1
Views: 65

### Standard Cell Potential[ENDORSED]

Are there any special rules or types of chemicals that aren't included when calculating the standard cell potential?
Mon Feb 25, 2019 4:04 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Max Potential [ENDORSED]
Replies: 1
Views: 89

### Max Potential[ENDORSED]

Why is max potential when very little current flows instead of when max current flows through the cell?
Mon Feb 25, 2019 4:03 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic Cells [ENDORSED]
Replies: 1
Views: 83

### Galvanic Cells[ENDORSED]

Is there ever a galvanic cell reaction that creates electrical energy without making a physical difference on the anode/cathode?
Tue Feb 19, 2019 8:07 pm
Forum: Van't Hoff Equation
Topic: Non-consistant enthalpy
Replies: 3
Views: 162

### Non-consistant enthalpy

What do you do if delta H isn't consistent? Can you still use this formula?
Tue Feb 19, 2019 8:02 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Factors
Replies: 2
Views: 106

### Factors

What factors influence the value of delta G in a reaction? Is it mainly influenced by what's present in the reaction or what is produced/given off?
Tue Feb 19, 2019 7:59 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Indications
Replies: 3
Views: 119

### Indications

Are there any characteristics of a reaction that would hint at the value of delta G being positive/negative or larger/smaller?
Mon Feb 04, 2019 1:26 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Examples of Open Closed Isolated
Replies: 5
Views: 169

### Re: Examples of Open Closed Isolated

An open system is any that has openings where matter and heat can be transferred into/out of, such as an open top cup. A closed system is one that doesn't have any physical openings, but can transfer heat through its walls, such as a closed box. And an isolated system is one that doesn't have any ph...
Mon Feb 04, 2019 1:15 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Closed and Isolated
Replies: 10
Views: 245

### Re: Closed and Isolated

If it's closed then matter can't be added or taken away from the system, such as a closed box, but heat can still transfer into and out of it. If the system is isolated, then it's like a highly insulated box where matter and heat both can't be transferred into or out of the system.
Mon Feb 04, 2019 1:12 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Outside Factors
Replies: 1
Views: 86

### Outside Factors

Is there ever a situation where the change in internal energy is affected by factors other than heat and work?
Mon Jan 28, 2019 7:35 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Extensive Vs Intensive Properties
Replies: 1
Views: 81

### Extensive Vs Intensive Properties

What's the difference between extensive and intensive properties (heat capacity vs specific heat capacity) and does it change how/when we use those things?
Mon Jan 28, 2019 7:27 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity
Replies: 5
Views: 178

### Heat Capacity

Since heat capacity and specific heat capacity are one calculation apart, when asked about heat capacity in a question should we assume they're asking about specific heat capacity? Will normal heat capacity ever be asked about?
Mon Jan 28, 2019 7:16 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimetry
Replies: 5
Views: 237

### Calorimetry

What's the difference between normal calorimetry and bomb calorimetry? Does normal just have constant pressure but anything else can change and bomb is the same idea but only volume can change?
Mon Jan 21, 2019 7:15 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Salt Solution
Replies: 5
Views: 365

### Salt Solution

When you're calculating the pH of a salt solution do you always ignore the ions that don't take part in the reaction and dissolve away?
Mon Jan 21, 2019 7:13 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Ionized vs Deprotonated
Replies: 2
Views: 102

### Ionized vs Deprotonated

What's the difference between % ionized vs % deprotonated? Are there different names that mean the same calculation?
Mon Jan 21, 2019 7:11 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Percent Protonation
Replies: 6
Views: 199

### Percent Protonation

For percent protonation is it the final concentration of the weak base over its initial concentration x100 or the concentration of the conjugate acid over the initial concentration of the weak base x100?
Mon Jan 14, 2019 8:24 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Weak Acid/Base Calculations
Replies: 2
Views: 124

### Weak Acid/Base Calculations

How do we find the pH/pOH and concentrations of H30+ and OH- of a reaction with a weak acid/base that doesn't completely dissociate?
Mon Jan 14, 2019 8:18 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: change in pressure
Replies: 4
Views: 162

### Re: change in pressure

Because of the same idea, if there are more moles on the right and pressure is added then the reaction will try to balance itself out by favoring the reverse reaction and going back to reactants.
Mon Jan 14, 2019 1:12 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: ICE Table [ENDORSED]
Replies: 3
Views: 191

### Re: ICE Table[ENDORSED]

The subscripts don't matter in the ice table, only the coefficients before the molecules of product or reactant affect the change in molarity in the ice table calculations and the powers the molarities are to in the final equilibrium constant calculation.
Wed Jan 09, 2019 10:18 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K
Replies: 4
Views: 114

### Re: K

If you're dealing with solutions that have a given concentration, then you use Kc, but if you're dealing with gases and partial pressures, you use Kp.
Wed Jan 09, 2019 10:16 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Equilibrium Constant
Replies: 2
Views: 46

### Equilibrium Constant

How do you calculate the equilibrium constant if you're given a mix of concentrations and pressures? Or will that never happen?
Wed Jan 09, 2019 10:14 am
Forum: Ideal Gases
Topic: Ideal vs Real Gas
Replies: 6
Views: 218

### Ideal vs Real Gas

What's the physical and chemical difference between ideal and real gases?
Fri Dec 07, 2018 1:22 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: pKa and Ka
Replies: 3
Views: 157

### Re: pKa and Ka

Ka tells you how well an acid dissolves in solution, but when simplified into pKa, the smaller the value is the stronger the acid, as strong acids dissociate more in solution.
Fri Dec 07, 2018 1:18 pm
Forum: Lewis Acids & Bases
Topic: Determining Factors
Replies: 2
Views: 133

### Determining Factors

What aspects of an acid/base's lewis structure tells you if it's an acid or base?
Fri Dec 07, 2018 1:16 pm
Forum: Conjugate Acids & Bases
Topic: Water as an Acid/Base
Replies: 20
Views: 627

### Water as an Acid/Base

Is water's identity as an acid or base solely determined by being the opposite of what it's reacting with?
Fri Nov 30, 2018 2:23 pm
Forum: Hybridization
Topic: Determining Factors
Replies: 3
Views: 156

### Determining Factors

Is hybridization always based off of the number of bonds or lone pair electrons around the central atom or are there other factors that could affect it?
Fri Nov 30, 2018 2:19 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs Lewis
Replies: 3
Views: 90

### Bronsted vs Lewis

What are the main differences between Bronsted and Lewis acids and bases?
Fri Nov 30, 2018 2:16 pm
Forum: Lewis Acids & Bases
Topic: Strength
Replies: 3
Views: 144

### Strength

What factors determine how strong or weak an acid/base is?
Sun Nov 25, 2018 11:42 am
Forum: Hybridization
Topic: Test 3
Replies: 13
Views: 298

### Re: Test 3

I think we don't have to know how to draw the 3-D hydbridization diagrams, but that we have to know how to make the electron configuration and understand how it works.
Sun Nov 25, 2018 11:39 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bonds
Replies: 2
Views: 83

### Bonds

Do single, double and triple bonds always have to be made from the exact number of sigma and pi bonds each time, or can they be made with other ratios of the two?
Sun Nov 25, 2018 11:35 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity
Replies: 6
Views: 190

### Polarity

Is a VSEPR model shape always polar if the central atom in the lewis structure has lone pairs? Or can lone pairs be symmetrical and cancel out charges to make the molecule non-polar?
Wed Nov 14, 2018 5:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape
Replies: 4
Views: 189

### Molecular Shape

What are all the factors that affect molecular shape determined from the lewis structure?
Wed Nov 14, 2018 5:09 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Strengths
Replies: 5
Views: 225

### Bond Strengths

Why are ionic bonds stronger than hydrogen bonds?
Wed Nov 14, 2018 4:15 pm
Forum: Octet Exceptions
Topic: Resonance Structures
Replies: 7
Views: 388

### Re: Resonance Structures

When you make a lewis structure that has resonance you need to draw all the resonance structures with double-sided arrows between them, as the correct lewis structure for the molecule is actually a hybrid of them all and not any single one.
Wed Nov 07, 2018 1:22 pm
Forum: Octet Exceptions
Topic: Central atoms with more than 8 electrons
Replies: 3
Views: 232

### Re: Central atoms with more than 8 electrons

Any element in the third period or below can have an expanded octet with more than 8 valence electrons. They do have a d-orbital and are large enough to stably hold more electrons in their shells. But, if you have more that 8 electrons in your lewis structure for a certain molecule, try to make sure...
Wed Nov 07, 2018 1:19 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Ideal lewis structure with Formal Charge
Replies: 4
Views: 2088

### Re: Ideal lewis structure with Formal Charge

To find the most ideal lewis structure you want to create one where the base element, or element in the center of the structure, has a formal charge of 0. If the overall molecule is an ion with a charge, then try to have the outer elements which are connected to the main base be the ones that carry ...
Wed Nov 07, 2018 1:16 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 11
Views: 401

### Re: Formal Charge

Formal charges don't always have to be zero, as if a molecule is an ion with a certain positive or negative charge, then at least one element in the structure must have a charge that makes all of the formal charges of the elements in the structure add up to zero. But, to find the most stable form of...
Tue Oct 30, 2018 3:45 pm
Forum: Octet Exceptions
Topic: central atoms with more than 4 bonds
Replies: 3
Views: 166

### Re: central atoms with more than 4 bonds

Lavelle said that elements in the third period and below are able to hold more than 8 valence electrons and stay stable. Since sulfur (S) is in the third period it can follow this rule, which is why it can hold 12 electrons.
Tue Oct 30, 2018 3:41 pm
Forum: Octet Exceptions
Topic: octet rule exceptions?
Replies: 5
Views: 277

### Re: octet rule exceptions?

Lavelle said that elements in the third period or below are able to hold more than 8 valence electrons, typically sulfur, silicon, phosphorus and chlorine are the main ones known to have this ability.
Tue Oct 30, 2018 3:32 pm
Forum: Resonance Structures
Topic: Resonance hybrid
Replies: 2
Views: 112

### Re: Resonance hybrid

If a molecule has resonance you must draw each possible lewis structure, bracket each structure, and draw double-sided arrows between them. In real life no single resonance lewis structure is "right," but the molecule is a hybrid of all the possibilities.
Fri Oct 26, 2018 1:40 pm
Forum: Lewis Structures
Topic: Octet Rule
Replies: 5
Views: 353

### Re: Octet Rule

Most elements need to have a complete octet of valence electrons in order to survive and be stable. Only certain elements such as sulfur, phosphorus, chlorine and silicon can hold more than 8 valence electrons and form a stable expanded octet and elements such as hydrogen can only handle 2 valence e...
Fri Oct 26, 2018 1:20 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 3
Views: 186

### Re: Drawing Lewis Structures

Atoms can be bonded together in the lewis structure in any pattern, but each main element, other than H, needs to have a full set of 8 electrons by the end. By using single, double and triple bonds, you can use the amount of valence electrons available and start to form the structure, experimenting ...
Fri Oct 26, 2018 1:16 pm
Forum: Lewis Structures
Topic: Lewis Dot Order
Replies: 10
Views: 228

### Re: Lewis Dot Order

There is no particular order that you have to put the elements of the structure in, as long as each main element has a full set of 8 electrons, other than elements like H which only need 2 electrons.
Mon Oct 15, 2018 4:32 pm
Forum: SI Units, Unit Conversions
Topic: Unit Conversions
Replies: 3
Views: 263

### Re: Unit Conversions

Just remember that the SI base units are kilograms(kg) for mass, meters(m) for length and seconds(s) for time. Then make sure you know the prefixes, such as mega, kilo, deci, centi, milli, etc, and the powers of ten from the original SI unit they represent.
Mon Oct 15, 2018 4:26 pm
Forum: Significant Figures
Topic: Module: Molarity #15
Replies: 6
Views: 641

### Re: Module: Molarity #15

Since 0.25 isn't followed by any other decimal values after the 5, normally this answer would and should be rounded to 0.2 since both of the values getting you to this answer had only one significant figure.
Mon Oct 15, 2018 4:19 pm
Forum: Properties of Electrons
Topic: Photon Momentum
Replies: 1
Views: 135

### Photon Momentum

In today's lecture we talked about De Broglie's Wave Equation, I don't understand how a photon can have momentum when it doesn't have a mass?
Wed Oct 10, 2018 11:54 am
Forum: Balancing Chemical Reactions
Topic: Where to start [ENDORSED]
Replies: 10
Views: 800

### Re: Where to start[ENDORSED]

I always start by balancing the more unique elements that only occur once on each side of the reaction equation. I then balance the more common elements that show up multiple times throughout the equation, such as H, O and C. After that I can finish balancing the equation with any elements that are ...
Wed Oct 10, 2018 11:49 am
Forum: Limiting Reactant Calculations
Topic: How to find the limiting reactant easily and quickly
Replies: 5
Views: 1127

### Re: How to find the limiting reactant easily and quickly

When I find the limiting reactant I always use the molar masses of the reactants to find how many moles of each the reaction has. After I do that I look at the molar ratios between the reactants to see how much of each is needed to react with the other. In the example 2A + 1B --> 3C, for every 2 mol...
Wed Oct 10, 2018 11:43 am
Forum: Limiting Reactant Calculations
Topic: Percent Yield [ENDORSED]
Replies: 13
Views: 1864

### Re: Percent Yield[ENDORSED]

Actual yield is the amount of product formed when performing the reaction in real life, theoretical yield is the maximum predicted amount of that same product formed if the reaction completely uses up its limiting reactant and doesn't lose any product due to error. The actual yield will almost alway...
Thu Oct 04, 2018 1:02 pm
Forum: Molarity, Solutions, Dilutions
Topic: molarity conversion
Replies: 7
Views: 185

### Re: molarity conversion

When using the formula m1v1=m2v2 always make sure the volume values you put in are in liters, and then if the question asks for the answer to be in mL or another form, convert from liters at the end.
Thu Oct 04, 2018 1:00 pm
Forum: Significant Figures
Topic: Sig Figs... when to round?
Replies: 7
Views: 302

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

Never round off by sig figs in the middle of the problem, but keep in mind the sig figs of each new value you are continually using in a problem. At the end of the problem look at the supposed sig figs the values you used had and then round off to that number of sig figs.
Thu Oct 04, 2018 12:54 pm
Forum: Balancing Chemical Reactions
Topic: Order of balancing an equation
Replies: 8
Views: 312

### Re: Order of balancing an equation

As others have said, I usually start by balancing the unique elements that only occur once that are not found in multiple reactants or products, then continue by balancing the more common elements that are spread throughout the equation, and finish by balancing elements that are standing alone, such...