## Search found 38 matches

Sat Mar 12, 2016 3:04 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: heat capacity
Replies: 2
Views: 441

### Re: heat capacity

I also think that because of ethene's double bond, it makes the molecules more rigid. Ethane has all single bonds and therefore the energy from the heat goes into the vibrations and rotating of the atoms which absorbs the energy before the bond does.
Sat Mar 12, 2016 3:02 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: heat capacity
Replies: 2
Views: 441

### Re: heat capacity

Ethane has more hydrogens than ethene because ethene has a double bond and therefore 2 less hydrogen. Therefore, ethane has a higher molar mass. Since ethane's molar mass is more, it has a higher heat capacity.
Thu Mar 03, 2016 7:33 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: How to solve with K without an A value?
Replies: 3
Views: 516

### Re: How to solve with K without an A value?

Therefore, if its' Ea is at 125 kj/mol, then it wont occur at room temp. You don't need to calculate anything.
Thu Mar 03, 2016 7:32 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: How to solve with K without an A value?
Replies: 3
Views: 516

### Re: How to solve with K without an A value?

In the organic textbook it says that a reaction will occur at room temperature if it's Ea is approximately lower than 80 kj/mol.
Thu Mar 03, 2016 7:30 am
Forum: *Free Energy of Activation vs Activation Energy
Topic: Gibbs Free energy
Replies: 1
Views: 325

### Re: Gibbs Free energy

This is what it says on page. 162 of the organic chem textbook Catalysts weaken the bonds that need to be broken (making deltaH less positive). They also bring the reactants together before the reaction occurs and place them in the correct orientation (making DeltaS less negative). With a less posit...
Mon Feb 29, 2016 3:18 pm
Forum: *Alkanes
Topic: Using Iso and Neo
Replies: 1
Views: 324

### Using Iso and Neo

I know that iso and neo are often used non-IUPAC names, but I am not sure how to classify something as iso or neo, or when to use it?

Also, can someone please explain what sec- and tert- are?
Sat Feb 27, 2016 3:13 pm
Forum: *Constitutional and Geometric Isomers (cis, Z and trans, E)
Topic: Constitutional Isomers
Replies: 2
Views: 404

### Re: Constitutional Isomers

When finding constitutional isomers, if you start with a typical straight chain of carbons, attaching another carbon to the end of the chain will not give you a unique structure but just the exact same structure. Therefore, attaching it towards the middle of the chain or other spots will usually giv...
Tue Feb 16, 2016 6:51 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Steady State or Pre-Equilibrium approach
Replies: 1
Views: 288

### Steady State or Pre-Equilibrium approach

Do we have to learn the steady state approach in the book or should we just study pre-equilibrium one he taught us in lecture?
Tue Feb 09, 2016 7:04 am
Forum: Phase Changes & Related Calculations
Topic: Winter 2013 Midterm Q2A.
Replies: 4
Views: 701

### Re: Winter 2013 Midterm Q2A.

For the q(ice), you have to convert it from ice to liquid water, so you use the 6.01*1000 J/mol, which is the standard enthalpy of physical change of ice. So now you have liquid water at 0 degrees Celsius and you need to get it to 16 degrees celsius and since you have liquid water then you need to u...
Sun Feb 07, 2016 9:02 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: 14.43
Replies: 2
Views: 407

### Re: 14.43

What about the NO3 in this problem? where did it go? why do we not use a half reaction for that?
Fri Feb 05, 2016 7:17 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Creating Diagrams and Reactions Question 13.15
Replies: 3
Views: 1668

### Re: Creating Diagrams and Reactions Question 13.15

Do we just flip it so that we get the desired reaction... and thats how we determine which equation becomes the oxidation reaction?
Fri Feb 05, 2016 7:15 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Creating Diagrams and Reactions Question 13.15
Replies: 3
Views: 1668

### Re: Creating Diagrams and Reactions Question 13.15

How do we know to flip the first equation? Why is that the oxidation reaction?
Tue Jan 26, 2016 8:45 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Quiz 1 Prep #8
Replies: 3
Views: 486

### Quiz 1 Prep #8

Cl2(g)$\rightarrow$ 2Cl(g)

Can someone explain why this reaction is spontaneous at high temperatures?
Mon Jan 25, 2016 6:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Limiting reagents significance in enthalpy problems
Replies: 1
Views: 1706

### Re: Limiting reagents significance in enthalpy problems

I figured it out. You use it to see how much heat was produced for that specific reaction.
Fri Jan 22, 2016 12:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Limiting reagents significance in enthalpy problems
Replies: 1
Views: 1706

### Limiting reagents significance in enthalpy problems

Why do we need to find the limiting reagents in problems where we are finding the work and enthalpy from chemical reactions? How do they effect our calculations? I don't know how to use the information I have once I find the limiting reagent. When I look at the solutions in 8.99 and 8.101, they find...
Fri Jan 22, 2016 12:18 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Implications of Constant temperature, pressure and volume
Replies: 1
Views: 314

### Implications of Constant temperature, pressure and volume

I'm having trouble keeping track of all these conditions and their effect on how we solve a problem. What does constant temperature imply about our system? What does constant pressure imply about our system? What does constant volume imply about our system? How would each condition effect how we sol...
Mon Jan 18, 2016 7:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Question 8.99
Replies: 3
Views: 624

### Re: Question 8.99

they are finding the enthalpy of reaction for the thermochemical equation using enthalpy of formations. See appendix 2A for the enthalpies of formation for the products and reactants you are looking for. HCl is listed, but for zinc chloride, you know it will dissociate into 1 mol Zn2+ (aq) and 2 mo...
Mon Jan 18, 2016 12:04 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Using Hess's Law
Replies: 2
Views: 372

### Re: Using Hess's Law

I think I answered my own question... I figured it out after analyzing it a little bit longer.
Nevermind guys...
Mon Jan 18, 2016 11:57 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Using Hess's Law
Replies: 2
Views: 372

### Re: Using Hess's Law

Oh wait... are we assuming these are all combustion reactions? Do we always use combustion reactions when using Hess's law?
Mon Jan 18, 2016 11:49 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Using Hess's Law
Replies: 2
Views: 372

### Using Hess's Law

When using Hess's law, how do you figure out what the other reactions are that we use to solve the main reaction? For example in 8.57, they only give you \Delta H c o (C 2 H 2 ,g)=-1300. kj/mol. \Delta H c o (C 2 H 6 ,g)=-1560. kj/mol, and \Delta H c o (H 2 ,g)=-286. kj/mol. I am not sure what to do...
Sat Jan 16, 2016 8:47 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity and Intermolecular forces
Replies: 1
Views: 1071

### Heat Capacity and Intermolecular forces

What is the correlation of heat capacity and intermolecular forces, if there is one?
Sat Jan 09, 2016 9:41 pm
Forum: Phase Changes & Related Calculations
Topic: phase change
Replies: 3
Views: 440

### phase change

Okay I get that when the temperature doesn't change on a graph... It means that there is a phase change going on. That's how we will be able to identify it, but I don't understand why the temp. doesn't change if it's changing states?
Thu Dec 03, 2015 12:51 pm
Forum: Conjugate Acids & Bases
Topic: oxoacids
Replies: 1
Views: 428

### oxoacids

I know that the more electron withdrawing atoms around a central atoms makes an acid stronger. This is why HClO 2 is a stronger acid than HClO. I know that having more oxygens increases the oxidation state of Cl. Why would the increasing of the oxidation state of Cl increase the strength of the acid...
Wed Dec 02, 2015 10:31 am
Forum: Bronsted Acids & Bases
Topic: Metal oxides
Replies: 2
Views: 439

### Re: Metal oxides

Yes, metal oxides are basic so therefore they should all form hydroxide ions in water.
Tue Dec 01, 2015 2:48 pm
Forum: Bronsted Acids & Bases
Topic: H2PO4- and [HPO4]2-
Replies: 1
Views: 22723

### H2PO4- and [HPO4]2-

H 2 P0 4 - is an acid and when it is in water it forms a hydronium ion and HPO 4 - , which is the conjugate base. However I thought that H 2 P0 4 - could give off two hydrogen atoms and so I thought that HPO 4 - could still be considered an acid because it still has the ability to give off another p...
Wed Nov 25, 2015 9:49 am
Forum: Conjugate Acids & Bases
Topic: Conjugates always inverse?
Replies: 1
Views: 385

### Re: Conjugates always inverse?

For the most part, the conjugates of acids will always be bases because once they donate that proton, they become negative ions and now have the ability to accept a proton since they just lost one and cannot donate any more protons. I think, but I'm not 100 percent sure, but the exception is when yo...
Tue Nov 17, 2015 7:15 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Dentates
Replies: 1
Views: 347

### Re: Dentates

You want to look at the amount to atoms with lone pairs to determine if it is polydentate. Atoms will not form more than one bond to the TM even if it has more than one lone pair. Oxygen has a formal charge of 0 when it has a double bond so therefore it won't form a bond to a TM.
Mon Nov 16, 2015 10:57 pm
Forum: Ideal Gases
Topic: P=nRT
Replies: 3
Views: 527

### Re: P=nRT

I am pretty sure r is an experimentally determined constant like ryderbergs or plancks.
Thu Nov 12, 2015 7:57 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determining monodentate versus polydentate by shape
Replies: 1
Views: 390

### Determining monodentate versus polydentate by shape

I understand that you can determine how many bonds it will make to the transition metal by looking at the amount of lone pairs a molecule has. However, I don't understand how shape plays a role in determining if a molecule is a polydentate or monodentate. Also, how does this relate to chelating comp...
Thu Nov 12, 2015 7:33 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determining if a Ligand is Polydentate
Replies: 6
Views: 1231

### Re: Determining if a Ligand is Polydentate

I think the best way is to draw the lewis structure so you can see which atoms have lone pairs.. however, I think there are some molecules that are complicated to draw..so I would suggest remembering certain molecules that are monodentate or polydentate..(i.e. en, edta, dien)
Thu Nov 12, 2015 7:29 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Determining if a Ligand is Polydentate
Replies: 6
Views: 1231

### Re: Determining if a Ligand is Polydentate

So an atom cannot donate more than one lone pair to a transition metal?
Sun Nov 01, 2015 9:12 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Molecular Orbital Theory when nuclear charge is less than 8
Replies: 1
Views: 231

### Molecular Orbital Theory when nuclear charge is less than 8

I understand that the sigma bonds are higher in energy for atoms with nuclear charges less than 8, but I do not understand why it is that way. Could someone please explain? (:
Sat Oct 24, 2015 3:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 1
Views: 266

### Bond Angles

I am confused on how you figure out bond angles because some molecules like methane (CH4) would seem to have a 90 degree angle from its Lewis structure and not a 109.5 degree angle
Sat Oct 17, 2015 4:00 pm
Forum: Octet Exceptions
Topic: Octet Exceptions and Formal Charge?
Replies: 1
Views: 439

### Re: Octet Exceptions and Formal Charge?

This is what I think. I would double check my information, but the formal charge does not need to be fixed at zero. Your formal charge of each atom in the molecule has to add up to equal to the charge of the molecule. So if you have an ion that has a negative two charge, you have to add up all your ...
Sat Oct 10, 2015 11:21 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: What does l mean?/ Subshells vs. Orbitals
Replies: 2
Views: 2801

### What does l mean?/ Subshells vs. Orbitals

I know l is supposed to be the angular momentum but how does that give us the shape of the orbital? How does it correspond to the subshells? Also, what is the difference between a subshell and orbital, I've been using them interchangeably.
Thu Oct 01, 2015 11:55 pm
Forum: Einstein Equation
Topic: HW 1.33
Replies: 4
Views: 610

### Re: HW 1.33

Yay..makes a lot more sense! Thank you!
Thu Oct 01, 2015 11:01 pm
Forum: Einstein Equation
Topic: HW 1.33
Replies: 4
Views: 610

### Re: HW 1.33

So the Debroglie equation is just a method used to find the wavelength of only subatomic particles.. while radiation only uses Einstein's equation as a method to find wavelength?
Thu Oct 01, 2015 9:57 pm
Forum: Einstein Equation
Topic: HW 1.33
Replies: 4
Views: 610

### HW 1.33

In exercise 1.33 it says the velocity of an electron that is emitted from a metallic surface by a photon is 3.6x10^3 km/s. Then it asks in "a" what is the wavelength of the ejected electron and in "c" it asks what is the wavelength of the radiation that caused the photoejection o...