## Search found 60 matches

Sun Mar 17, 2019 3:04 pm
Forum: General Rate Laws
Topic: slow step
Replies: 11
Views: 585

### Re: slow step

You can also look at the rate values(if given) and compare--the bigger the rate, the faster it is. The rate constant, k, is directly proportional to the rate, so the bigger the k, the bigger the rate=faster reaction. The rate determining step, being the slowest, should usually have the smallest k an...
Sun Mar 17, 2019 2:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q
Replies: 6
Views: 455

### Re: Q

No, unless the problem states for you to use standard concentrations.
Sun Mar 17, 2019 2:54 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work done vs work on system
Replies: 18
Views: 1415

### Re: Work done vs work on system

Work done by the system results in a loss of energy from the system. This means that the internal energy is decreasing due to work. As a result, work is negative. Work being done on the system by outside forces means that energy is being inputted into the system. This makes the work positive.
Sun Mar 10, 2019 8:51 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Negative Order
Replies: 4
Views: 409

### Re: Negative Order

Negative integer: A negative order indicates that the concentration of that species INVERSELY affects the rate of a reaction.
So, yes, if a species has a negative order, then it participates in a reverse reaction, thereby leading to a decrease in the reaction rate(slowing it down).
Sun Mar 10, 2019 8:45 pm
Forum: Second Order Reactions
Topic: Equations
Replies: 2
Views: 1563

### Re: Equations

He said that he just showed us how the equations are derived to help us understand the concept behind each of them. We only need to know the final forms and their applications.
Sun Mar 10, 2019 4:23 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: Unique Average Rate
Replies: 5
Views: 264

### Re: Unique Average Rate

Also, the book says that the unique average rate "does depend on the coefficients used in the balanced equation." Why is this the case? I thought unique average rate of change takes care of the stoichiometric coefficient differences between the reactions and products?
Sun Mar 03, 2019 6:19 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: "Strongly oxidizing"
Replies: 5
Views: 237

### Re: "Strongly oxidizing"

Cu2+(aq) being a better oxidizing agent means that it wants electrons more than H+(aq), meaning that it has greater affinity with electrons/attracts electrons more. This means that it is more likely for Cu2+(aq) to be reduced than H+(aq). So, Cu2+(aq) is more likely to reduce itself(gain electrons) ...
Sun Mar 03, 2019 6:10 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: K Value
Replies: 7
Views: 318

### Re: K Value

Significant figures are usually derived from the problem itself. Using the Nernst Equation should not be the determinant of how many significant figures will be used for K.
Sun Mar 03, 2019 6:06 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Large K value
Replies: 5
Views: 229

### Re: Large K value

Yes, the reaction should be favorable in the reverse direction.
Sun Feb 24, 2019 4:57 pm
Forum: Balancing Redox Reactions
Topic: Oxygen Oxidation Number
Replies: 3
Views: 170

### Re: Oxygen Oxidation Number

O2 will have an oxidation number of 0 because it is in its elemental form.
Oxygen will have a -1 ON when it is found in peroxides (e.g. H202).
Everything else will yield a -2 ON for Oxygen.
Sun Feb 24, 2019 4:49 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Max Potential
Replies: 1
Views: 80

### Max Potential

Can someone explain why max cell potential is achieved when there is very little current flow?
Sun Feb 24, 2019 4:47 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Reversing Anode
Replies: 2
Views: 121

### Re: Reversing Anode

Yes, the anode is always reversed because we always flip the reaction that is being oxidized(located at the anode). When the voltage is negative, it means that the reaction is not spontaneous because ΔG is negative. Since a normal battery reaction is spontaneous(via the galvanic cell), we want posit...
Sun Feb 17, 2019 8:44 pm
Forum: Calculating Work of Expansion
Topic: Work
Replies: 8
Views: 511

### Re: Work

So far, the only type of work we talked about is work through expansion/compression. For this, you only really need to remember(and understand) the work equation at constant pressure (w=-PΔV) and the work equation for reversible and isothermic configurations (w=-nRTln(V2/V1)).
Sun Feb 17, 2019 8:38 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 4
Views: 221

### Re: Spontaneity

"At constant temperature and pressure, the direction of spontaneous change is the direction of decreasing Gibbs free energy."
The more negative the Gibbs Free Energy value is, the more spontaneous a process becomes.
Sun Feb 17, 2019 8:18 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs Free Energy
Replies: 7
Views: 286

### Gibbs Free Energy

What does it mean when Gibbs Free Energy changes? How does this affect the system?
Sun Feb 10, 2019 9:12 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Term Differences (Heat, Enthalpy, Temperature, and Work)
Replies: 4
Views: 499

### Term Differences (Heat, Enthalpy, Temperature, and Work)

Can someone define heat, enthalpy, temperature, and work?
Sun Feb 10, 2019 9:09 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat as path function
Replies: 3
Views: 139

### Heat as path function

Why is heat, like work, not a state function?
Sun Feb 10, 2019 9:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: q unit
Replies: 1
Views: 89

### q unit

Should q(heat) be in kJ or J?
Sun Feb 03, 2019 7:10 pm
Forum: Calculating Work of Expansion
Topic: Varieties of Work (Table 4A.1 (7th Edition))
Replies: 1
Views: 74

### Varieties of Work (Table 4A.1 (7th Edition))

Are we required to know the different types of work listed on Table 4A.1 (7th Edition) such as expansion, extension, raising weight, electrical, and surface expansion along with their formulas and units?
Sun Feb 03, 2019 6:51 pm
Forum: Calculating Work of Expansion
Topic: Free expansion
Replies: 3
Views: 161

### Free expansion

Can you give an example of a system that is doing a free expansion?
Sun Feb 03, 2019 6:46 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Adding inert gases into system
Replies: 1
Views: 112

### Adding inert gases into system

What would happen to the equilibrium of a system if an inert gas is added into it while keeping the volume constant? What would happen if the inert gas is added while the volume is allowed to change? Also, wouldn't adding additional gas particles within a system lead to an overall increase in the pr...
Sun Jan 27, 2019 8:12 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Catalysts in Kc
Replies: 6
Views: 259

### Re: Catalysts in Kc

Adding catalysts does not change the equilibrium because all it does is speed up the rate at which the system reaches equilibrium by lowering the activation energy required to proceed with the reaction(forward reaction rate and reverse reaction rate are changed equally). Also, catalysts do not chang...
Sun Jan 27, 2019 8:04 pm
Forum: Ideal Gases
Topic: Approximations for ICE
Replies: 20
Views: 531

### Re: Approximations for ICE

Given the K value, if K<<10^-3, then you may make the approximation. If K is not given, then make the approximation, but be sure to check if the value of x that you found is, indeed, less than 5% of the initial value(s)(concentration/partial pressure)of the components in the system. If x<5% of the i...
Sun Jan 27, 2019 7:52 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Inert Gas
Replies: 6
Views: 254

### Re: Inert Gas

When an inert gas is added to a system in equilibrium with constant volume, the pressure of the system will go up, but, since the concentrations of the products and reactants do not change, there will be no shifts in the equilibrium. However, if the volume is not constant, the equilibrium will shift...
Sun Jan 20, 2019 9:34 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changing partial pressure of components vs changing pressure of system
Replies: 2
Views: 127

### Changing partial pressure of components vs changing pressure of system

Will there be a difference in effects if the pressure of the entire system is changed instead of changing only the partial pressure of the components of the system?
Sun Jan 20, 2019 9:27 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Shortcut method (finding concentration change)
Replies: 5
Views: 169

### Shortcut method (finding concentration change)

Can someone explain the reasoning behind the shortcut method which can be used to bypass the quadratic equation when solving for the change in molarity(x)?
Sun Jan 20, 2019 9:21 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K=1
Replies: 2
Views: 79

### K=1

If the equilibrium constant is equal to 1, what does it mean? Does it mean that the system is at equilibrium?
Sun Jan 13, 2019 5:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Aqueous Solutions [ENDORSED]
Replies: 2
Views: 111

### Aqueous Solutions[ENDORSED]

Why are aqueous solutions used when determining the equilibrium constants, while liquids are not?
Sun Jan 13, 2019 5:40 pm
Forum: Ideal Gases
Topic: When is pv=nrt used? [ENDORSED]
Replies: 5
Views: 224

### Re: When is pv=nrt used?[ENDORSED]

Also, the constants sheet should have the gas constant, R, on it. For this, use the most appropriate form so you will have common units. As for temperature, T, it should be given in the problem. Like the previous answer stated, use the Ideal Gas Law to convert between concentration and partial press...
Sun Jan 13, 2019 1:56 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solving for K
Replies: 7
Views: 182

### Re: Solving for K

Brackets indicate the concentration of whatever is inside the brackets. This means that you're solving for Kc.
Parenthesis just indicates groupings and multiplication. This is not conclusive in that you can be dealing with partial pressures or concentrations.
Sun Dec 09, 2018 8:17 pm
Forum: Bronsted Acids & Bases
Topic: Oxoacids
Replies: 1
Views: 360

### Oxoacids

Why is an oxoacid stronger with more oxygens?
Sun Dec 09, 2018 8:12 pm
Forum: Lewis Acids & Bases
Topic: HClO4 Strength
Replies: 1
Views: 288

### HClO4 Strength

Why is perchloric acid considered a strong acid?
Sun Dec 09, 2018 8:09 pm
Forum: Naming
Topic: naming polydentate ligands
Replies: 2
Views: 352

### Re: naming polydentate ligands

All polydentate ligands will have prefixes bis, tris, etc. whenever more than one of them is involved. Ligands do not necessarily have to have the prefixes bi, tri, tetra, etc. to get the prefixes(bis, tris, etc.).
Sun Dec 02, 2018 10:21 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: charges
Replies: 1
Views: 108

### Re: charges

No, the charges in acid and base reactions are not found by calculating formal charges. The charges are based on the properties of the elements themselves(electronegativity, electron affinity, ionization energy, etc.). The charges are basically derived from the fact that elements either gained or lo...
Sun Dec 02, 2018 9:48 pm
Forum: Naming
Topic: Ions with more than one possible charge
Replies: 1
Views: 62

### Ions with more than one possible charge

How is it possible for certain elements to have more than one possible ion(different charges), like Ti +2, +3,+4?
Sun Dec 02, 2018 9:38 pm
Forum: Dipole Moments
Topic: Strength of intramolecular forces due to polarity
Replies: 5
Views: 255

### Strength of intramolecular forces due to polarity

How does polarity affect the strength of intramolecular force?
Sun Nov 25, 2018 10:03 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Like dissolves like
Replies: 3
Views: 182

### Like dissolves like

Based on the rule: like dissolves like, I know that polar solvent dissolves polar compounds. However, I do not know how non-polar solvent dissolves non-polar compounds. Can someone explain? Is it because of London Dispersion Forces? If so, won't non-polar solvent still be able to dissolve polar comp...
Sun Nov 25, 2018 9:56 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Properties and Polarity
Replies: 1
Views: 74

### Covalent Properties and Polarity

When ionic compounds exhibit covalent properties(cation attract the electrons of the anion), is the polarity of the anion affected?
Sun Nov 25, 2018 9:53 pm
Forum: Bond Lengths & Energies
Topic: Bond Energy
Replies: 1
Views: 143

### Bond Energy

Can someone explain the concept/mechanics behind bond energies? Why is energy released when a bond is formed? Conversely, why is energy needed in order for a bond to break?
Sun Nov 18, 2018 9:12 pm
Forum: General Science Questions
Topic: Chemistry Community Posts
Replies: 8
Views: 655

### Re: Chemistry Community Posts

@katie_sutton1A
As of November 18, 2018, we should have 21 posts.
Sun Nov 18, 2018 9:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular Shape Patterns
Replies: 5
Views: 221

### Re: Molecular Shape Patterns

I think we pretty much have to memorize the conditions for each shape. Making use of the VSEPR notation helps a lot, but it still requires that you know the conditions of each shape. As for trends, I am not aware of any existing.
Sun Nov 18, 2018 6:41 pm
Forum: Ionic & Covalent Bonds
Topic: Electron Distortion
Replies: 1
Views: 134

### Electron Distortion

Can someone explain what a distorted electron is? Also, how does it relate to polirizability?
Sun Nov 11, 2018 9:09 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: Induced Dipole - Induced Dipole
Replies: 1
Views: 69

### Induced Dipole - Induced Dipole

How does increasing the molar mass result in stronger attractive interactions in this type of force(Induced Dipole - Induced Dipole)?
Sun Nov 11, 2018 8:19 pm
Forum: Ionic & Covalent Bonds
Topic: Silver Halides
Replies: 3
Views: 202

### Silver Halides

Why is the solubility among the silver halides (from AgF to AgI) decreasing(less soluble) as the size of the anion gets bigger? I thought that increasing the size of the components of a compound increases the compound's solubility(more soluble) because the bond holding it together gets weaker due to...
Sun Nov 11, 2018 8:13 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent vs Ionic Characteristics
Replies: 2
Views: 144

### Covalent vs Ionic Characteristics

What exactly are covalent characteristics? From the Na+ Cl- example, is the electrostatic pull of the cation, Na+, on the electrons of the anion, Cl-, the covalent characteristic? If so, are there others? Also, what is the ionic characteristic of this example?
Sat Nov 03, 2018 11:15 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum number Ms
Replies: 3
Views: 421

### Re: Quantum number Ms

A specific valence electron must be specified. For example, 2p^ 6 . In this case, the 3 orbitals of the p subshell(px,py, and pz) must be filled accordingly by following the Pauli Exclusion Principle and the Hund's Rule. Distribute the electrons, using up and down arrows to represent the electron sp...
Sat Nov 03, 2018 10:30 pm
Forum: Trends in The Periodic Table
Topic: Problem 1F.11 (7th Edition)
Replies: 3
Views: 154

### Problem 1F.11 (7th Edition)

I know someone already asked this, but no one has answered it yet, so... The problem is asking which element in each of the following pairs have higher electron affinity. a. Te or I b. Be or Mg c. O or S d. Ga or In Why does Sulfur have a higher electron affinity compared to oxygen? I thought electr...
Sat Nov 03, 2018 10:20 pm
Forum: Trends in The Periodic Table
Topic: Periodic trends of elements diagonal to one another
Replies: 1
Views: 81

### Periodic trends of elements diagonal to one another

When comparing elements based on the different periodic trends, how do you decide which of the two elements diagonal to one another is going to have a larger value than the other? Like, for example, when comparing the ionization energies of lithium and magnesium, fluorine and arsenic, selenium and i...
Sun Oct 28, 2018 9:54 pm
Forum: Trends in The Periodic Table
Topic: Horizontal Trend (Group 2 and Group 13)
Replies: 3
Views: 409

### Re: Horizontal Trend (Group 2 and Group 13)

Thanks! Then can you also explain why group 15 elements with half-filled valence p shell have lower ionization energy than the group 17 elements with the almost-filled(just needs 1 more electron to fill up)p shell? Does it have to do with increased electrostatic attraction between the nucleus and th...
Sun Oct 28, 2018 9:30 pm
Forum: Trends in The Periodic Table
Topic: Horizontal Trend (Group 2 and Group 13)
Replies: 3
Views: 409

### Horizontal Trend (Group 2 and Group 13)

According to the first ionization energy periodic table trend, a movement from the left side to the right side of the periodic table will yield increasing ionization energy values. However, when I looked up the actual first ionization energies of the different elements I found that some elements fro...
Sun Oct 28, 2018 9:12 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 4s becomes higher energy
Replies: 3
Views: 1378

### 4s becomes higher energy

While I know that electron shells fill up based on the Aufbau principle(lower energy levels fill up before higher energy ones), I do not understand how the 4s becomes higher energy after it fills up and 3d becomes lower energy. I also don't understand why elements before atomic number 21 fill in the...
Sun Oct 21, 2018 9:02 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers (Magnetic Quantum Number)
Replies: 1
Views: 146

### Quantum Numbers (Magnetic Quantum Number)

How are the magnetic quantum numbers derived? Also, how are the quantum numbers connected to the Schrödinger Wave Equation?
Sun Oct 21, 2018 8:44 pm
Forum: Properties of Light
Topic: Problem 1A.3
Replies: 3
Views: 181

### Problem 1A.3

Can someone explain why the answer to this problem is: c) "The extent of the change in the electrical field at a given point decreases"? I know that the other choices are wrong, but I don't know how to explain that this choice is right. The problem reads: "Which of the following happe...
Sun Oct 21, 2018 8:37 pm
Forum: Administrative Questions and Class Announcements
Topic: Spectral Series and Tests
Replies: 1
Views: 108

### Spectral Series and Tests

For any of the upcoming tests, do we have to memorize the different Spectral Series? Which aspects do we have to know by heart?
Sun Oct 14, 2018 9:01 pm
Forum: General Science Questions
Topic: Electron Energy Levels
Replies: 2
Views: 247

### Electron Energy Levels

When an electron moves up to its highest energy state, is it possible for that electron to lose just a part of the energy it gained, or does it have to lose all of it?
Sun Oct 14, 2018 8:41 pm
Forum: General Science Questions
Topic: White Light
Replies: 2
Views: 228

### White Light

During lecture we talked about how in order to find the wavelengths of the different electromagnetic radiation within the EM Spectrum, white light is passed through a glass prism. How can white light possess different wavelengths of light? Also, why is black light not used?
Sun Oct 14, 2018 2:50 pm
Forum: General Science Questions
Topic: Chemistry Community Posts
Replies: 8
Views: 655

### Chemistry Community Posts

If you posted more than 3 times on Chemistry Community in one week, will the posts that went over the weekly post requirement be counted for next week's post requirement?
Sat Oct 06, 2018 1:00 am
Forum: General Science Questions
Topic: Orbitals
Replies: 2
Views: 224

### Orbitals

Why do we fill out the 4s orbital first before filling out the 3d orbital?
Thu Oct 04, 2018 12:59 am
Forum: General Science Questions
Topic: Moles vs Number of Molecules
Replies: 5
Views: 378

### Moles vs Number of Molecules

In this combustion reaction: CH4 + 2O2 → CO2 + 2H20 (or any chemical reactions, really), I've been hearing people read it as "1 mole of CH4 reacts with 2 moles of Oxygen to produce 1 mole of CO2 and 2 moles of H2O," while some also read it as "1 molecule of CH4 reacts with 2 molecules...
Thu Oct 04, 2018 12:31 am
Forum: Student Social/Study Group
Topic: Percent Composition
Replies: 3
Views: 631

### Percent Composition

What will you have to do if the mass percent of the different elements that make up a compound/molecule does not add up to 100%? Like, for example, if the percent composition is, like, 41% C, 25% O, and 22% H. 41+25+22≠100. Also, is it alright to assume that a 99.96% composition is close enough to 1...