## Search found 33 matches

Fri Mar 11, 2016 7:41 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Winter 2014 Final Q1C vaporization term
Replies: 1
Views: 307

### Winter 2014 Final Q1C vaporization term

Why on this question is there a 1/2 in front of the m*deltaH? Isn't the equation always q=m*C*deltaT+m*deltaH? I don't understand the vaporization term used here.
Fri Mar 11, 2016 7:02 pm
Forum: *Cycloalkenes
Topic: Winter 2013 Final Q6A, naming
Replies: 1
Views: 442

### Winter 2013 Final Q6A, naming

The possible answers to name this cycloalkene with 4 methyl substituents is either 2,3,4,4 tertmethylcyclohex-1-ene or 1,5,5,6 tetramethylcyclohex-1-ene. Since the double bond is #1 in both cases wouldn't we prefer the other numbers to be 2,3,4,4 since they are almost all lower than 1,5,5,6?
Fri Mar 11, 2016 6:44 pm
Forum: General Rate Laws
Topic: Winter 2013 Final Q4C reaction rate
Replies: 2
Views: 440

### Winter 2013 Final Q4C reaction rate

Given the initial concentration of a product, reaction quotient, time, and change in concentration of product, how do we find the reaction rate? This solution takes the change in concentration and divides it by the time but what does the change in product have to do with the reaction rate?
Thu Mar 10, 2016 8:57 pm
Forum: Balancing Redox Reactions
Topic: Winter 2011 Final Q3A
Replies: 1
Views: 298

### Winter 2011 Final Q3A

Q3A asks for the balanced redox equation of: MnO2(s) + ClO-(aq) -> MnO4^2-(aq)+Cl-(aq). The solution given balances the oxygens in the equation using OH- and then H2O to balance the hydrogens. Why do we not balance the oxygens with H2O and the hydrogens with H+ to produce an oxidation half reaction ...
Sun Mar 06, 2016 3:59 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Cis and trans in line structures
Replies: 1
Views: 378

### Cis and trans in line structures

I understand what cis and trans molecules refer to but how did Dr Lavelle know that the second line structure on page 105 of our course reader is trans just by looking at it? I have drawn the Lewis structure and am still unsure.
Wed Feb 17, 2016 1:25 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Finding order
Replies: 1
Views: 339

### Finding order

When finding the order of a reaction, if you write out the rate equation, can you just count the exponents to give the order?
Sat Feb 13, 2016 11:14 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: Comparing experiments to find order rxn
Replies: 2
Views: 357

### Comparing experiments to find order rxn

When comparing three experiments to determine the order of reaction, when do you compare 1 to 2 and 2 to 3 vs comparing 1 to 2 and 1 to 3, as the book does?
Sun Feb 07, 2016 12:14 am
Forum: Balancing Redox Reactions
Topic: electrochemistry ch question 13.d
Replies: 2
Views: 496

### Re: electrochemistry ch question 13.d

Given the balanced equation above we can tell the Au + (aq) going to Au 3+ (aq) is being oxidized because the charge is increase because it is losing electrons. Thus, this is the anode. The Au + (aq) going to Au(s) is being reduced because the charge is reducing. Thus this is the cathode. When writi...
Sun Feb 07, 2016 12:06 am
Forum: Balancing Redox Reactions
Topic: electrochemistry ch question 13.d
Replies: 2
Views: 496

### Re: electrochemistry ch question 13.d

You have to break that into two reactions Au + (aq) goes to Au(s) Au + (aq) goes to Au 3+ (aq) from there add electrons as needed so the charge of both sides of each reaction is equal. This will look like 2e - plus 2Au + (aq) goes to 2Au(s) Au + (aq) goes to Au 3+ (aq) plus 2e - add these together t...
Thu Jan 28, 2016 9:33 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Determining degeneracy
Replies: 1
Views: 279

### Determining degeneracy

Do the placement of double bonds effect degeneracy? For example, does benzine have a W of 1 or 2?
Wed Jan 27, 2016 1:05 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Units of molar capacity
Replies: 3
Views: 324

### Re: Units of molar capacity

Yes, the increments between degrees Celcius and Kelvin are the same. Ex: 1 degree C = 274 K and 2 degrees C = 275 K
Tue Jan 26, 2016 9:57 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Finding change in entropy with no numbers
Replies: 1
Views: 261

### Finding change in entropy with no numbers

If you are not given any values of temperature or heat and the products and reactants are in the same state (ex: Practice Quiz 1 winter 2014 number 8), how do you know if the change in entropy is positive or negative? In this example, Cl2 gas becomes 2 Cl gas.
Mon Jan 25, 2016 2:18 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Extensive v Intensive Properties
Replies: 1
Views: 222

### Extensive v Intensive Properties

What are the differences between extensive and intensive properties and what are their implications in chemistry?
Mon Jan 25, 2016 2:14 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Reversible v Irreversible Reactions
Replies: 1
Views: 298

### Reversible v Irreversible Reactions

I understand the concept behind reversible reactions, but what exactly defines an irreversible reaction?
Mon Jan 25, 2016 2:10 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Units of molar capacity
Replies: 3
Views: 324

### Units of molar capacity

On page 6 or 21 of our course reader it states "molar heat capacity, J per degree K per mole" and right underneath says "heat required to raise temp of 1 mole of a substance by 1 degree C." So I am confused as to weather molar heat capacity is measured in degrees K or degrees C. ...
Wed Jan 13, 2016 12:48 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Stirer increasing heat in calorimeter
Replies: 1
Views: 250

### Stirer increasing heat in calorimeter

Wouldn't the motion of the stir-er in a calorimeter increase the temperature of the water that is being used to measure the temperature increase upon combustion?
Sat Dec 05, 2015 4:22 pm
Forum: Lewis Structures
Topic: Determining which element to give a formal charge
Replies: 3
Views: 588

### Re: Determining which element to give a formal charge

Why can't Cl have an expanded octet? Our book states "nonmetal atoms in Period 3 or later periods can expand their valence shells," and Cl is a non metal in period 3.
Thu Dec 03, 2015 12:06 am
Forum: Lewis Structures
Topic: Determining which element to give a formal charge
Replies: 3
Views: 588

### Determining which element to give a formal charge

When drawing a lewis structure, is there a method to decide which element will receive the formal charge? For example, if I can arrange electrons/ bonds to give either Cl or O a formal charge of 1-, how do I decide which way to draw it? For example when drawing SO2Cl-, you can either attach one O to...
Wed Dec 02, 2015 11:52 pm
Forum: Lewis Structures
Topic: Lewis Structure of SO2
Replies: 1
Views: 445

### Lewis Structure of SO2

Why is it correct to draw the lewis structure of SO2 with a 1+ charge on the S and a 1- charge on an O? Why wouldn't you use two double bonds to attach each O to the central S resulting in no formal charge anywhere?
Wed Dec 02, 2015 9:27 pm
Forum: Calculating the pH of Salt Solutions
Topic: 2010 Final Q7B neutralization reaction
Replies: 2
Views: 619

### 2010 Final Q7B neutralization reaction

What is the definition of a neutralization reaction? How do CH3COOH and NaOH neutralize each other? Specifically, how to we figure out the moles of CH3COOH and CH3COO- after neutralization?
Tue Dec 01, 2015 4:06 pm
Forum: Calculating the pH of Salt Solutions
Topic: Determining if a compound is a salt
Replies: 1
Views: 351

### Determining if a compound is a salt

How can you tell a compound is a salt? What factors make KBr a salt, for example?
Sun Nov 29, 2015 10:29 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted vs Lewis acids and bases
Replies: 3
Views: 821

### Bronsted vs Lewis acids and bases

What is the difference between Bronsted and Lewis acids and bases? How do you choose which label to primarily call a compound?
Fri Nov 13, 2015 10:07 pm
Forum: Naming
Topic: Formula of ethylenediaminetetraacetato
Replies: 2
Views: 518

### Re: Formula of ethylenediaminetetraacetato

Is C10H16N2O8 correct?
Fri Nov 13, 2015 10:05 pm
Forum: Naming
Topic: Formula of ethylenediaminetetraacetato
Replies: 2
Views: 518

### Formula of ethylenediaminetetraacetato

What is the formula for ethylenediaminetetraacetato? The textbook only includes a diagram.
Thu Nov 12, 2015 8:43 pm
Forum: Naming
Topic: Implied Ion Ligand. Homework 17.29
Replies: 1
Views: 244

### Implied Ion Ligand. Homework 17.29

In homework problem 17.29, problem a and c include the ligands CN. Since there is no negative subscript after CN, how are we supposed to know they are implying it's the CN ion?
Wed Nov 11, 2015 4:03 pm
Forum: Hybridization
Topic: How do you find hybridization?
Replies: 3
Views: 869

### Re: How do you find hybridization?

Another way to determine hybridization is to simply count the regions of high electron density (lone pairs and bonds) and then build your hybridization from lowest energy (s subshell) to highest (g subshell). So for benzine, each carbon has three bonds (one to the hydrogen and two to the adjacent ca...
Wed Nov 11, 2015 3:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Determining if a reaction is in equilibrium
Replies: 1
Views: 246

### Determining if a reaction is in equilibrium

Is there a way to determine if a reaction is in equilibrium if you are not given the K value?
Tue Nov 03, 2015 10:17 pm
Forum: Sigma & Pi Bonds
Topic: Fall 2010 Midterm Q6: Identifying composition of bonds
Replies: 1
Views: 293

### Fall 2010 Midterm Q6: Identifying composition of bonds

When identifying the composition of sigma and pi bonds does it matter which element we list first in the parenthesis? For example, are are sigma(C2sp^2, O2sp^2) and sigma (O2sp^2, and C2sp^2) interchangeable or do they mean different things?
Sun Nov 01, 2015 7:40 pm
Forum: Lewis Structures
Topic: FC when drawing Lewis Structures on ionic compounds
Replies: 1
Views: 400

### FC when drawing Lewis Structures on ionic compounds

When drawing a Lewis Structure for an ionic compound, O2^2- for example, is it better for one atom to have a formal charge of 2- or both atoms to have a formal charge of 1- to produce an overall charge of 2-?
Tue Oct 20, 2015 10:25 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions in electron configuration
Replies: 1
Views: 3574

### Exceptions in electron configuration

Are all elements in groups 6 and 11 of the d-block of the periodic table exceptions when writing electron configurations like Chromium and Copper are? Since they all have full d5 and d10 subshells I feel like this is logical but have been taught that only Cr and Cu are exceptions.
Mon Oct 12, 2015 12:44 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Oribitals, value of m
Replies: 1
Views: 311

### Oribitals, value of m

How do we know which of the many values of m when l>0 are correct? For example, for l=3, m= [-3, -2, -1, 0, 1, 2, 3]. Which of these seven numbers is accurate and tells us the orientation?
Sun Oct 04, 2015 11:09 pm
Forum: DeBroglie Equation
Topic: Rest Mass
Replies: 1
Views: 278

### Rest Mass

What exactly is rest mass and how do we know that photons, for example, have no rest mass?
Sun Oct 04, 2015 10:56 pm
Forum: SI Units, Unit Conversions
Topic: How do you go from meter to nanometer? [ENDORSED]
Replies: 7
Views: 1993

### Re: How do you go from meter to nanometer?[ENDORSED]

The back of our text book has a very helpful list of SI prefixes. For example, nano- is 10^-9. Thus, a nanometer is equal to 1 x 10^-9 meter. Knowing this, you can cross multiply the value you found (3.4 x 10^-7 m) with the conversion factor of 1 nm per 1 x 10^-9 m to reach 340 nm.