## Search found 25 matches

Fri Mar 17, 2017 12:39 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 2014 Midterm Question 3
Replies: 3
Views: 466

### Re: 2014 Midterm Question 3

If I am not mistaken, the reduction potentials and any other necessary information will be provided on the back of the equation sheet. The equation sheets for each individual exams have been omitted and replaced with a general equation sheet at the beginning of the practice exams section. You can st...
Sat Mar 11, 2017 10:30 pm
Forum: *Ethers
Topic: Numbering of Substituents
Replies: 1
Views: 591

### Numbering of Substituents

On page 70 of the introduction to organic chemistry book, why is the compound named 3-chloro-1-ethyl-1-methoxycyclohexane instead of 1-chloro-3-ethyl-3-methoxycyclohexane. Alchabetically the first substituent chloro should get the higher number shouldn't it? Is it because the oxy-substituent is give...
Sun Mar 05, 2017 1:37 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Section 4 question 30
Replies: 1
Views: 233

### Section 4 question 30

Question 30 in section 4 states that a reaction will NOT occur at room temperature if the activation energy is 125 kj/mol. What is used to figure out that the reaction will not proceed at 298 kelvin?
Fri Feb 24, 2017 12:01 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Heterogenous catalysts
Replies: 1
Views: 296

### Heterogenous catalysts

Can heterogeneous catalysts bind to more than one molecules involved in a reaction?
And also, is a catalyzed reaction more exothermic than a non catalyzed reaction?
Sun Feb 19, 2017 10:47 am
Forum: General Rate Laws
Topic: Chapter 15 question 15
Replies: 1
Views: 318

### Chapter 15 question 15

In chapter 15 question 15, the questions sets up a direct relationship between the the concentration of the reactants and the rate of production of the products. So the rate law comes out to rate=k[CH3Br][OH] How do we know that the rate is first order? And I'm also curious as to how the rate law wo...
Fri Feb 10, 2017 2:40 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Midterm 2015 Q. 2 and 3 part C [ENDORSED]
Replies: 1
Views: 313

### Midterm 2015 Q. 2 and 3 part C[ENDORSED]

In part B of question 2&3 of practice midterm 2015, It shows that the delta H of 1 mol of water is 42 kj/mol. But in part C, this calculated value for delta H of water is being used as the delta H for the reaction H(rxn). Why is 42 kj/mol being used for the entire reaction.
Mon Feb 06, 2017 2:05 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.23 Cathode vs Anode differentiation [ENDORSED]
Replies: 1
Views: 368

### 14.23 Cathode vs Anode differentiation[ENDORSED]

I don't understand why in chapter 14 question 23 part B, a value of 0.92 was used as the cathode and 1.09 as the anode. After separating the equation into its half reaction components (with the electrons added to the reactants side), how do we know which half reaction we have to use as anode and whi...
Sun Feb 05, 2017 11:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Number of mols to use in the equation [ENDORSED]
Replies: 3
Views: 512

### Number of mols to use in the equation[ENDORSED]

When calculating the standard Gibbs free energy of a galvanic cell, I'm confused where we acquire the value for n. I know this is supposed to be the number of electrons transferred, but must we do a full redox and oxidation half reaction balancing procedure in order to attain the number of electrons...
Tue Jan 31, 2017 2:47 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Delta S of formation vs Delta S
Replies: 1
Views: 519

### Delta S of formation vs Delta S

In question 9.55, we are asked to give delta H, S, and G. When calculating, the answer book shows that the Delta S of formation (Delta S with subscript r) is calculated. But on the bottom, it simply gives the Delta S for the product with the notation being Delta S with a subscript m. What does this ...
Sun Jan 29, 2017 4:25 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Spontaneous Reactions
Replies: 4
Views: 607

### Spontaneous Reactions

Is there work being done by or on the system if the reaction is sponanteous?
Sun Jan 22, 2017 8:48 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Homework Problem 8.19 and 8.21
Replies: 2
Views: 347

### Re: Homework Problem 8.19 and 8.21

In order for the heat to be transferred to the water, it must first raise the temperature of the copper. In both cases, we use q=mC[delta]T where we input the mass of the copper kettle (given), the specific heat capacity of copper (table 8.2), and the change in temperature (final T -initia T). Repea...
Sun Jan 15, 2017 1:27 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8015
Views: 1401610

### Re: Post All Chemistry Jokes Here

Technically speaking, chemistry teaches us that alcohol is a solution... do with that information what you will.
Sun Dec 04, 2016 11:19 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8015
Views: 1401610

### Re: Post All Chemistry Jokes Here

Suffice it to say that we can call a carbon ring with iron atoms in place of the carbons as a Ferrous wheel?

Sorry for the transition metal pun, Cu in class today!
Sat Nov 26, 2016 12:37 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Placement of Electrons in Orbitals
Replies: 2
Views: 499

### Re: Placement of Electrons in Orbitals

The electron would be removed or added in a heterogenous diatomic molecule in the order in which the orbitals are filled. The same order that the electrons are filled (up and to the right) will be used to add the electron in BO- and one will be removed from the last filled orbital in BO+
Tue Nov 15, 2016 2:42 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Finding Coordination Number and Oxidation State [ENDORSED]
Replies: 7
Views: 2127

### Re: Finding Coordination Number and Oxidation State[ENDORSED]

Yes. Polydentate ligands can bond to the transition metal at more than one site, therefor a bidentate ligand has two areas on it which can bond to the central transition metal atom. This allows bidentate ligands to be considered as 2 coordination numbers when counting the total number of bonds.
Fri Nov 11, 2016 3:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K and Q calculations
Replies: 1
Views: 304

### K and Q calculations

In some questions it Is asked to write the reaction quotient Q or the equilibrium expression K. The answers for these seem to switch between calculating with the partial pressure P[product]/P[reactant] and calculating with Kc instead without the notation for partial pressure being involved in the eq...
Mon Nov 07, 2016 12:30 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8015
Views: 1401610

### Re: Post All Chemistry Jokes Here

I don't get why my stomach hurts this bad. Me and my friend went to a bar together after our chemistry midterm, he asked for H2O and I asked for H2O too. It tasted pretty funny though.
Tue Oct 25, 2016 2:11 pm
Forum: Resonance Structures
Topic: Resonance structures [ENDORSED]
Replies: 3
Views: 630

### Resonance structures[ENDORSED]

When forming resonance structures, can one resonance structure be a double bond with an oxygen atom and the other resonance structure be a double bond with a nitrogen atom? Or must the resonance structure be with the same elemental species within the molecule?
Mon Oct 24, 2016 10:49 am
Forum: Photoelectric Effect
Topic: Octet rule
Replies: 1
Views: 340

### Octet rule

Can oxygen have an octet with only a single bond? When drawing a Lewis structure, does it matter which atoms receive lone pairs of electrons so long as the total number of electrons remains constant? I counted the total number of electrons for the atoms that form a compound and kept the total consis...
Wed Oct 19, 2016 2:14 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy of Oxygen [ENDORSED]
Replies: 1
Views: 296

### Re: Ionization Energy of Oxygen[ENDORSED]

The solutions manual gives the following explanation : "A ground state oxygen atom has four electrons in the p-orbitals. This configuration means that as one goes across the periodic table in period 2, oxygen is the first element encountered in which the p-electrons must be paired. This added e...
Tue Oct 11, 2016 5:44 pm
Forum: Quantum Numbers and The H-Atom
Topic: Magnetic Quantum number
Replies: 2
Views: 395

### Re: Magnetic Quantum number

My mistake, we get -1,0,1 for an principle quantum number value of 2. So how are these numbers related to px, py, and pz orbitals.
Tue Oct 11, 2016 5:42 pm
Forum: Quantum Numbers and The H-Atom
Topic: Magnetic Quantum number
Replies: 2
Views: 395

### Magnetic Quantum number

When finding magnetic quantum number for let's say a principle quantum number n=2, we get m= -2,-1,0,1,2. I'm confused how these values get translated into px, py, pz subshells, since magnetic quantum number describes the different orbitals of a subshell.
Sun Oct 09, 2016 2:01 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Uncertainty
Replies: 11
Views: 2103

### Re: Uncertainty

I'm having the exact same problem. I went through the calculation multiple times and consistently end up with 6.4 instead of 3.2. Which is exactly double what the answer should be. I'm confused why the workbook is giving an answer that's half the value I calculated.
Thu Oct 06, 2016 4:48 pm
Forum: Balancing Chemical Reactions
Topic: Naming Compounds
Replies: 2
Views: 501

### Re: Naming Compounds

Hi Kelsey, in a previous post a student asked how familiar we should be with naming compounds and Chem_Admin posted stating that we should have a general idea of naming compounds but it will be a topic that we will later be discussing and hopefully mastering (if I'm not mistaken). However, this reso...
Wed Sep 28, 2016 11:55 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Accuracy vs Precision [ENDORSED]
Replies: 5
Views: 1758

### Re: Accuracy vs Precision[ENDORSED]

Hi Ashlyn, these pictures have always been helpful to me in clarifying the difference between accuracy and precision. It's a simplified way of discerning between the two and realizing why they are important in calculations. http://www.carolina.com/images/teacher-resources/activities/accuracy-vs-prec...

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