Search found 29 matches
- Sat Mar 12, 2016 10:32 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Residual entropy
- Replies: 1
- Views: 443
Residual entropy
Why does NO have greater residual entropy than BF3?
- Sat Mar 12, 2016 10:26 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Comparing heat capacities in Final 2011
- Replies: 1
- Views: 369
Comparing heat capacities in Final 2011
In question 1C it says that ethane has a higher heat capacity than ethane. Why would this be true, wouldn't it be harder to heat up the triple bonds than the double bonds?
- Tue Mar 01, 2016 3:42 pm
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: question 4.31 in the Intro to Organic Chem book
- Replies: 1
- Views: 321
question 4.31 in the Intro to Organic Chem book
Hi, for #31 we're supposed give the overall rate law for the reaction. Why is the overall rate law for this reaction just the first step of the reaction? is there some significance to that? Also, why is the rate constant larger for the second step, if it requires less activation energy? I'm having t...
- Fri Feb 26, 2016 2:42 pm
- Forum: *Nucleophiles
- Topic: question 4.25 in ochem book
- Replies: 1
- Views: 370
question 4.25 in ochem book
Hi! for question 25 in chapter 4 we're supposed to use curved arrow to indicate electron movement in the reaction. In this case our nucleophile is Br2. I was wondering why one Br molecule is more electronegative than the other one, as shown in the answer key. Thank you!
- Fri Feb 19, 2016 12:54 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Slow reaction vs fast reaction
- Replies: 2
- Views: 2392
Slow reaction vs fast reaction
How can we tell when a reaction is fast, or when it is too slow to be important? How can we tell which step is slow?
- Wed Feb 10, 2016 9:57 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: help with midterm 2012 q 7A
- Replies: 1
- Views: 338
help with midterm 2012 q 7A
Where did the value 0.34V come from? for the standard cell potential of the anode. is there an equation we're supposed to use? thank you!
- Sun Feb 07, 2016 7:36 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: midterm 2011 question 6
- Replies: 1
- Views: 404
midterm 2011 question 6
how do we determine which half-reaction would create the largest voltage? does it stem from the g= -nFE equation?
- Sun Feb 07, 2016 4:42 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: 2011 midterm q4
- Replies: 3
- Views: 540
2011 midterm q4
i was just wondering, when solving for K, why the product concentration is 2x and not just x? thank you!
- Mon Feb 01, 2016 11:03 pm
- Forum: Balancing Redox Reactions
- Topic: example 14.1
- Replies: 1
- Views: 325
example 14.1
can someone explain the oxidation half-reaction part of this example? I'm just confused about why C2 has an oxidation number of +3 when C usually has an oxidation number of 4.
thank you
thank you
- Mon Feb 01, 2016 10:59 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing redox reactions
- Replies: 1
- Views: 355
Re: Balancing redox reactions
For balancing half reactions in both acidic and basic solutions, balance the elements that are not H or O first. Then balance the O atoms by adding H20. The balancing of these half reactions differ in this next step; in acidic solution, balance H by using H+. In basic solution, balance H by using H2...
- Mon Feb 01, 2016 6:20 pm
- Forum: Balancing Redox Reactions
- Topic: Help with chapter 14 example 14.1
- Replies: 1
- Views: 299
Help with chapter 14 example 14.1
Why does O4- have a charge of -2 in this example? I don't understand step 1 of this example. so basically how does oxygen have an oxidation number of -2?
- Tue Jan 26, 2016 10:25 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: problem 8.67 b
- Replies: 1
- Views: 300
problem 8.67 b
Does anyone know where we can find the value to "atomize 1 mol C" for this problem? I don't see the same 717 kJ/mol value in appendix 2a or anything
- Tue Jan 26, 2016 9:21 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Homework problem 8.65
- Replies: 1
- Views: 354
Homework problem 8.65
Can someone help clarify #65 for me? We're trying to get to the equation N2 + 5/2 O2 --> N205 but at the end of the problem the solution is to subtract twice the enthalpy of NO from the formation of N205 because we don't need it... but we don't have N2 in the equation. Do we not need it because we w...
- Wed Jan 20, 2016 5:26 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: help with example 9.5
- Replies: 1
- Views: 307
help with example 9.5
Where did the Cv,m value of 12.47 J/K*mol come from in Step 2 of example 9.5? Is that something we can look up or was it calculated somewhere..?
- Wed Jan 20, 2016 4:26 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Help with Self test 9.4A
- Replies: 1
- Views: 325
Help with Self test 9.4A
Hi, self test 9.4A asks to calculate the change in entropy from 20.00 bar to 5.00 bar. Why do we ignore the bar in our calculation and continue to use the gas constant 8.314 J /K*mol instead of the .08314 L. bar/K*mol?
- Mon Jan 11, 2016 10:20 pm
- Forum: Phase Changes & Related Calculations
- Topic: Self-Test 8.9A
- Replies: 1
- Views: 292
Self-Test 8.9A
Can someone help me with self-test 8.9A on page 244? I converted the number of grams of benzene, 39.1 g, to its molar mass. I then found that there are 2 mols of benzene in the sample and multiplied that by the amount of heat to get 30.8 kJ mol, even though the answer should be in kJ per mol.
- Sun Jan 10, 2016 4:08 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: homework 8.27
- Replies: 1
- Views: 334
homework 8.27
In question 8.27 we're presented with two different pressures, one from the calibration of a piston and the other for an irreversible expansion. When solving for work done for both reversible and irreversible expansions, how do we know when to use which pressure?
- Wed Dec 02, 2015 8:59 pm
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Weak acid
- Replies: 1
- Views: 417
Weak acid
Why does HF make a weak acid?
- Sun Nov 29, 2015 10:40 pm
- Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
- Topic: Solving for x in calculating pH questions
- Replies: 2
- Views: 445
Solving for x in calculating pH questions
Why do we sometimes ignore the x in the denominator of the ratio of concentrations and sometimes we keep it there, for when we are solving for x in the questions that ask to find the pH?
- Sat Nov 28, 2015 1:30 am
- Forum: Lewis Acids & Bases
- Topic: Acids and bases
- Replies: 2
- Views: 585
Acids and bases
how can we tell if an acid is weak or strong?
- Mon Nov 16, 2015 9:51 pm
- Forum: Naming
- Topic: Drawing ICE box
- Replies: 1
- Views: 367
Drawing ICE box
When drawing the ICE box, how do you know when the change in partial pressure is positive or negative?
- Mon Nov 16, 2015 8:46 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Calculating equilibrium constant
- Replies: 1
- Views: 424
Calculating equilibrium constant
When calculating the equilibrium constant, can we use the pressure of one thing and the concentration of another, or do we have to convert them to one or the other?
Naming
What are the trends for the periodic table with regards to their charges? Like how the row next to the noble gases are all negative 1, what are the trends for the rest of the table?
- Sun Nov 08, 2015 8:08 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Molecular orbital order
- Replies: 1
- Views: 296
Molecular orbital order
Does anyone know why for Nitrogen and below, the sigma p orbital is located above the two pi orbitals, but it moves to above the pi orbitals for oxygen and above? this was probably mentioned in class but I was just wondering out of curiousity!
- Sun Oct 25, 2015 10:55 pm
- Forum: Electronegativity
- Topic: Strongest CX bond, where X is a halogen
- Replies: 2
- Views: 1850
Strongest CX bond, where X is a halogen
I'm having trouble with a problem from chapter 3 number 87. We're supposed to determine which molecule would have the strongest bond, CF4, CCL4, or CBr4. The book says CF4 would have the strongest bond because it has the shortest bond, but this is an exception to the electronegativity argument. C an...
- Sun Oct 18, 2015 11:03 pm
- Forum: Ionic & Covalent Bonds
- Topic: Structures of Polyatomic Species
- Replies: 1
- Views: 467
Structures of Polyatomic Species
I'm confused about something in the course reader on page 67. When making a structure of a polyatomic species, the example used (NH4)2SO4, and it has 9 valence electrons. how do we know that its minus 1 e or (NH4)+? why does that happen? same thing with the SO4, how do we know its SO4 minus 2 electr...
- Sat Oct 10, 2015 5:23 pm
- Forum: Lewis Structures
- Topic: Valence Electrons
- Replies: 5
- Views: 330
Re: Valence Electrons
The first orbital, the s orbital, can hold two electrons at most. Every shell after the first can hold up to eight electrons. One can tell how many valence electrons an element has by taking its atomic number and seeing how many electrons are left over from the first 2 electrons plus 8 each shell th...
- Fri Oct 02, 2015 3:34 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg's Indeterminacy equation
- Replies: 1
- Views: 426
Heisenberg's Indeterminacy equation
Why is it okay to have an uncertainty of velocity less than the speed of light but not greater than? I know Dr. Lavelle went over this in class but the answer is still not clear to me
- Thu Oct 01, 2015 2:33 pm
- Forum: Properties of Light
- Topic: Spectroscopy
- Replies: 1
- Views: 384
Spectroscopy
I didn't understand this topic until I read it over in the book, so I wanted to clarify what spectroscopy is in case anyone doesn't understand it. I understand spectroscopy to be a part of chemistry that deals with understanding how light is emitted or absorbed by certain substances. Scientists had ...