Search found 21 matches
- Mon Mar 07, 2016 9:21 pm
- Forum: *Alkenes
- Topic: Heat Capacity of Ethene
- Replies: 1
- Views: 585
Re: Heat Capacity of Ethene
Ethane is a single bond so it has more freedom to move. Ethene is a double bond so it is more rigid, which makes movement more difficult. More rotational modes, or more freedom to move, means it has a higher heat capacity. Ethane is also more complex than ethene because it has 2 more hydrogen atoms,...
- Wed Mar 02, 2016 11:01 am
- Forum: *Alkanes
- Topic: Tert and sec groups chemical formula?
- Replies: 1
- Views: 585
Re: Tert and sec groups chemical formula?
The tert example given in the course reader was a butyl group, so it is C(CH 3 ) 3 . Sec is when the central carbon is attached to the second carbon in the chain. So for example, sec-butyl would be CH 3 CH 2 CH 2 CH 3 which the second carbon attached to the methyl group coming off of the longest cha...
- Thu Feb 25, 2016 2:48 pm
- Forum: *Free Energy of Activation vs Activation Energy
- Topic: Whether a reaction will occur at room temperature
- Replies: 2
- Views: 4047
Re: Whether a reaction will occur at room temperature
A reaction will occur at room temperature if is activation energy is less than 80kJ/mol. In general, the activation energies tend to range from 40 to 150 kJ/mol.
- Mon Feb 15, 2016 9:29 am
- Forum: Reaction Mechanisms, Reaction Profiles
- Topic: Course Reader page 75
- Replies: 2
- Views: 681
Re: Course Reader page 75
At equilibrium, the rates of the forward and reverse reactions are equal. Because of this, the equilibrium constant for a reaction is equal to the ratio of the rate constants for the forward and reverse reactions that contribute to the overall reaction. You can see how this is derived on page 781 in...
- Tue Feb 09, 2016 1:01 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Electrodes in Cell Diagrams
- Replies: 1
- Views: 461
Re: Electrodes in Cell Diagrams
You put Pt(s) in the cell diagram in general if all of the substances in the half-reaction are aqueous. The anode/cathode should be a solid (I think there might be 1 or 2 cases where the anode/cathode is a liquid). If there is no solid in the reaction, Pt(s) is used as the anode/cathode. For example...
- Tue Feb 02, 2016 2:30 pm
- Forum: Balancing Redox Reactions
- Topic: Redox Reactions
- Replies: 1
- Views: 434
Re: Redox Reactions
A redox reaction is basically a reaction that involves a transfer of electrons between 2 substances. The substance that gains electrons is reduced, and the substance that provides or loses its electrons is oxidized. The oxidation number of the substances are changed when they are reduced or oxidized...
- Thu Jan 28, 2016 4:08 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 4
- Views: 1672
Re: Bond Enthalpies
Yes, the bonds that are broken will be in the reactants, and the bonds that are formed will be in the products. Drawing the Lewis structures of each reactant and product will help you see which bonds are broken and which bonds are formed. For example, in homework problem #8.73b, the following reacti...
- Tue Jan 19, 2016 10:40 am
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: HW 9.1 Rate of entropy of generation
- Replies: 1
- Views: 1024
HW 9.1 Rate of entropy of generation
#9.1: "A human body generates heat at the rate of about 100. W (1 W 1 Js1). (a) At what rate does your body heat generate entropy in your surroundings, taken to be at 20. C?" In the solutions manual, they derived the following equation: Rate of entropy generation = \Delta Ssurr/time =...
- Tue Jan 12, 2016 2:05 pm
- Forum: Calculating Work of Expansion
- Topic: Reversible and irreversible process
- Replies: 2
- Views: 672
Re: Reversible and irreversible process
A reversible process is when a very small change reverses the direction of the system. The change in internal energy is 0 in a reversible isothermal expansion. In an irreversible process, the direction of the system does not change. Usually in a problem, they will tell you if a process is reversible.
- Fri Jan 08, 2016 3:21 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Characteristics that give higher heat capacities?
- Replies: 3
- Views: 2428
Re: Characteristics that give higher heat capacities?
To give you an example of a characteristic related to higher heat capacity, you can look at #8.29. The question asks which molecule, NO or NO 2 , has the higher molar heat capacity. The answer is NO 2 because it is the more complex molecule. Complex molecules tend to have higher heat capacities beca...
- Fri Dec 04, 2015 8:27 pm
- Forum: Properties & Structures of Inorganic & Organic Bases
- Topic: Acid Strength
- Replies: 1
- Views: 997
Acid Strength
In this problem, how do you know that H has more electron withdrawing ability than CH 3 ? Fall 2013 Final Exam: #Q7B "List the following acids in order of increasing strength and explain why: CF 3 COOH (1), CH 3 COOH (2), CCl 3 COOH (3), C(CH 3 ) 3 COOH (4)" Answer: 4<2<3<1 Electron withdr...
- Fri Nov 27, 2015 12:14 am
- Forum: Bronsted Acids & Bases
- Topic: Determining Acids and Bases
- Replies: 5
- Views: 1118
Re: Determining Acids and Bases
You can also tell if an acid/base is strong by looking at its ionization in water. If it is nearly or completely ionized, you know it is strong. If only a few molecules are ionized, you know the acid/base is weak.
- Sat Nov 21, 2015 8:48 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: how will equilibrium shift
- Replies: 3
- Views: 618
Re: how will equilibrium shift
You can also think of this in terms of pressure. Volume and pressure have an inverse relationship according to the PV=nRT equation, so if volume is increased, then pressure is decreased. A decrease in pressure favors the side with more moles of gas, so the equilibrium will shift in the direction whe...
- Tue Nov 10, 2015 8:51 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Naming
- Replies: 2
- Views: 632
Re: Naming
When you are given the name of a coordination compound, how do you know what order to write the ligands in when you are writing the coordination compound's chemical formula? Do you just write the ligands in the alphabetical order that they are given in?
- Thu Nov 05, 2015 9:08 pm
- Forum: Lewis Structures
- Topic: Lewis Structure of HClO3
- Replies: 3
- Views: 25533
Lewis Structure of HClO3
When drawing the Lewis structure of HClO3, how do you know that the H atom is bonded to the O instead of to the central Cl atom?
- Sat Oct 31, 2015 12:41 pm
- Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
- Topic: Full MO Energy Diagram
- Replies: 1
- Views: 328
Full MO Energy Diagram
If we are asked for the full molecular energy diagram of a diatomic molecule, would we just have to include the 1s orbital? In diatomic molecules that don't include hydrogen, would we ever have to include the 1s orbital in our MO energy diagram?
- Fri Oct 30, 2015 3:42 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lone Pair Repulsion in Bent Molecules
- Replies: 5
- Views: 1670
Re: Lone Pair Repulsion in Bent Molecules
[/img] http://www.chemthes.com/icon_2/3508.gif Hi! In the case of AX2E3, it is considered linear. If you look at how the lone pairs are shown in the image, you can see in what directions the lone pairs are pulling. Because of this lone pair arrangement, a linear shape is formed. Overall since it's l...
- Sat Oct 24, 2015 12:53 am
- Forum: Resonance Structures
- Topic: Resonance
- Replies: 2
- Views: 824
Re: Resonance
For example, look at O3. There are 3 O atoms. The central O atom has a double bond with 1 of the O atoms, and it has a single bond with the other O atom. You know this structure has resonance because you can switch which atom has the double bond and which has the single bond without there being any ...
- Sat Oct 17, 2015 3:18 pm
- Forum: Lewis Structures
- Topic: Drawing & Determining Correct Lewis Structure
- Replies: 4
- Views: 958
Re: Drawing & Determining Correct Lewis Structure
Looking at the (SO4)2- example given in class, the Lewis structure that had atoms with formal charges of 0 was more stable than the Lewis structure in which the formal charge of the sulfur/oxygen atoms was > or < 0. I think if you check the formal charge of the structures, you should be able to dete...
- Fri Oct 09, 2015 6:55 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg Equation Purpose
- Replies: 2
- Views: 706
Re: Heisenberg Equation Purpose
I think the purpose of the equation is mostly to estimate the movement of a particle. Because particles are constantly moving, its hard to specify where exactly they are location-wise, so the Heisenberg Equation tries to locate a particle based on delta x, where x is the uncertainty of the particle'...
- Sat Oct 03, 2015 12:14 pm
- Forum: *Shrodinger Equation
- Topic: Shrodinger Equation
- Replies: 1
- Views: 600
Shrodinger Equation
For what kinds of problems will we use this equation? What does the equation signify?