Search found 23 matches

by Katherine_Zhuo_3B
Sun Mar 12, 2017 6:23 pm
Forum: *Cycloalkanes
Topic: Cyclo-
Replies: 7
Views: 1186

Re: Cyclo-

For cycloalkanes,You look at the numbering for the lowest number on substituents, and if they are equal, you number based on first named.
by Katherine_Zhuo_3B
Sun Mar 12, 2017 6:20 pm
Forum: *Alkenes
Topic: Naming what carbon the double/triple bond is on?
Replies: 2
Views: 394

Re: Naming what carbon the double/triple bond is on?

When naming the double and triple bonds, you number the bond based on which carbon it starts on.
by Katherine_Zhuo_3B
Wed Mar 08, 2017 10:36 am
Forum: *Alkanes
Topic: Iso and Neo Prefixes
Replies: 5
Views: 711

Re: Iso and Neo Prefixes

I believe the prefix iso- is not restricted to 4 or less carbons, and you can tell when it is used when the line structure has a branch of CH(CH3)2
by Katherine_Zhuo_3B
Wed Mar 08, 2017 10:34 am
Forum: General Science Questions
Topic: Types of energy profiles
Replies: 5
Views: 885

Re: Types of energy profiles

The potential energy profile is generally used by physical chemist's and refer to activation energy, while the free energy profile is generally used by organic chemists.
by Katherine_Zhuo_3B
Wed Mar 08, 2017 10:32 am
Forum: *Free Energy of Activation vs Activation Energy
Topic: Catalysts and Entropy
Replies: 3
Views: 1023

Re: Catalysts and Entropy

I believe that entropy is less negative because by putting the molecules in the correct order and orientation, there is greater facilitation to the reaction occurring, which leads to more entropy.
by Katherine_Zhuo_3B
Fri Feb 24, 2017 5:54 pm
Forum: First Order Reactions
Topic: Slope of k
Replies: 3
Views: 574

Re: Slope of k

For zero and first order reactions, the slope = -k. For second order reactions, the slope = +k.
by Katherine_Zhuo_3B
Tue Feb 14, 2017 9:27 am
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: how to calculate n correctly
Replies: 4
Views: 566

Re: how to calculate n correctly

For n, the moles of e-, does it have a unit, or is it just the number. For example, in deltaG=-nFE, if F is C/mol and E is J/C, is the n units mol so that delta G is J or is does the n have no units so that delta G =J/mol?
by Katherine_Zhuo_3B
Tue Feb 14, 2017 9:23 am
Forum: Balancing Redox Reactions
Topic: Balancing equations
Replies: 10
Views: 1072

Re: Balancing equations

General polyatomic ions such as NO3-, SO42-, will need to be known, as well as common charges such as O2-, H1+, and 1+ charges for alkali metals.
by Katherine_Zhuo_3B
Wed Feb 01, 2017 2:29 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Change in entropy= q/T [ENDORSED]
Replies: 3
Views: 469

Re: Change in entropy= q/T [ENDORSED]

Since the change in entropy is equated by q/T, as T increases, the overall change in entropy is decreasing if the heat (q) remains the same.
by Katherine_Zhuo_3B
Wed Jan 25, 2017 11:55 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibbs v internal
Replies: 1
Views: 323

Re: Gibbs v internal

U stands for internal energy, and delta U stands for the change in internal energy, which can be calculated by delta U = q + w. G is for Gibbs Free Energy, and delta G stands for the change in free energy of a system, which can help determine the spontaneity and favorability of a reaction. There are...
by Katherine_Zhuo_3B
Sat Jan 21, 2017 7:19 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: kJ vs. kJ/mol [ENDORSED]
Replies: 1
Views: 275

Re: kJ vs. kJ/mol [ENDORSED]

Generally, the standard enthalpy of formation is in kJ/mol, and for the standard enthalpy of reaction, answers are generally kJ. You can determine the kJ/mol for standard enthalpy of reaction by looking at the chemical equation.
by Katherine_Zhuo_3B
Sun Jan 15, 2017 8:16 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Specific heat capacity [ENDORSED]
Replies: 2
Views: 545

Re: Specific heat capacity [ENDORSED]

In a reaction, anytime a bond is formed, it is an exothermic reaction. This is because energy is released when the bonds are formed. To express that the reaction is exothermic, the delta H is negative. In a perfect system where qsys =- qsurr, this equation is derived from the 1st Law of Thermodynami...
by Katherine_Zhuo_3B
Wed Nov 30, 2016 11:38 am
Forum: Identifying Acidic & Basic Salts
Topic: Identifying a salt
Replies: 4
Views: 774

Re: Identifying a salt

So looking at NH4Cl, we have the cation NH4+ and anion Cl-. In a solution, the concentration of Cl- does not change, nor does it affect the pH of the solution. However, NH4+ is a weak acid, and so it will want to react with the water molecules to form NH3 (the more stable molecular form), and H3O+.
by Katherine_Zhuo_3B
Sun Nov 27, 2016 11:58 pm
Forum: Lewis Acids & Bases
Topic: How to determine which is an acid and which is a base?
Replies: 5
Views: 784

Re: How to determine which is an acid and which is a base?

Given NH3 (aq), by memorizing the strong/weak acids and bases, we know that NH3 is a weak base. The lone pair on the nitrogen will bond with neighboring hydrogens from the H2O to form conjugate acid NH4+ and conjugate base OH-.
by Katherine_Zhuo_3B
Sun Nov 20, 2016 11:41 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient Less than or Greater than 1 [ENDORSED]
Replies: 3
Views: 3062

Re: Reaction Quotient Less than or Greater than 1 [ENDORSED]

Q is the reaction quotient, which measures which direction a reaction will proceed given the initial partial pressures or concentrations. K is the equilibrium constant, which is a ration of products to reactants that does not change for the same reactions under the same conditions.
by Katherine_Zhuo_3B
Wed Nov 16, 2016 10:49 pm
Forum: Naming
Topic: Alphabetizing Ligands
Replies: 4
Views: 474

Re: Alphabetizing Ligands

For the formula, as long as you put the transition metal first, the ligands can be put in any order following the metal.
by Katherine_Zhuo_3B
Mon Nov 14, 2016 3:35 pm
Forum: Naming
Topic: Trans and Cis
Replies: 3
Views: 520

Re: Trans and Cis

An example would be the one we saw in class, where cis-diamminedichloroplatinum has the chlorides both on the left, whereas the trans-diamminedichloroplatinum has the chlorides located on opposite sides of each other.
by Katherine_Zhuo_3B
Sat Nov 05, 2016 3:35 pm
Forum: Properties of Light
Topic: Balmer and Lyman Series [ENDORSED]
Replies: 4
Views: 841

Re: Balmer and Lyman Series [ENDORSED]

The principal quantum number is an integer that describes the energy level of the electron. As n increases, the number of electronic shells increases and the electron is further from the nucleus and therefore has a higher energy. To compute n, we can utilize Rydberg's equation given the energy: En=-...
by Katherine_Zhuo_3B
Tue Oct 25, 2016 10:30 am
Forum: Dipole Moments
Topic: Dipole Moment in a Lewis Structure
Replies: 5
Views: 1461

Re: Dipole Moment in a Lewis Structure

With the arrow showing us the delta positive pole and delta negative pole, we can determine which atom in the molecule has a higher electronegativity than the other, and will pull the shared electrons closer when sharing.
by Katherine_Zhuo_3B
Tue Oct 18, 2016 11:38 am
Forum: Ionic & Covalent Bonds
Topic: The Octet
Replies: 3
Views: 575

Re: The Octet

Elements that are exceptions to the octet rule include P, S, Cl. This is because they are located in period 3 on the periodic table, meaning that they have l= 0,1,2. This corresponds to the s, p, and d orbitals. Hence, in their valence shell, they have d-orbitals that can accomadate additional e-. T...
by Katherine_Zhuo_3B
Sat Oct 15, 2016 1:13 am
Forum: DeBroglie Equation
Topic: Neutrons
Replies: 4
Views: 716

Re: Neutrons

In fact, all matter has wavelike properties. However, only those with small mass and high velocity have wavelike properties that could be detected. For everyday objects such as baseballs, it is difficult to detect the wavelike properties.
by Katherine_Zhuo_3B
Tue Oct 04, 2016 1:03 pm
Forum: Properties of Electrons
Topic: Energy Level Model [ENDORSED]
Replies: 2
Views: 601

Re: Energy Level Model [ENDORSED]

When the energy of a photon matches the energy difference between quantum levels, (which are represented by the lines shown in the model below), electrons will get excited and move to the next level. The arrows are pointing downwards as the model is showing the emission of energy as electrons return...
by Katherine_Zhuo_3B
Wed Sep 28, 2016 11:58 am
Forum: Significant Figures
Topic: Easy Way to Calculate Sigfigs
Replies: 6
Views: 1036

Re: Easy Way to Calculate Sigfigs

Yes, if there is a decimal, you would count the non-zero digits as sig figs. For example, 300. would be 3 sig figs. In cases such as numbers like 0.00500 however, since the preceding zeroes are simply place holders to put decimals in the correct location, the only numbers that are counted as sig fig...

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