Search found 22 matches

by Preston_Dang_1B
Wed Mar 15, 2017 5:00 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: 5/2R vs 3/2R
Replies: 2
Views: 273

Re: 5/2R vs 3/2R

If the substance you are dealing with is a monatomic ideal gas, then you can substitute Cp for 5/2R and Cv for 3/2R.

Hope this helps!
by Preston_Dang_1B
Mon Mar 06, 2017 6:52 pm
Forum: *Alkanes
Topic: Iso and Neo Prefixes
Replies: 5
Views: 545

Re: Iso and Neo Prefixes

Iso- is used to name a substituent chain that has a specific orientation of carbon and hydrogen atoms, (CH 3 ) 2 CH-. You would then determine the name of the whole substituent based on how many total carbon atoms there are in the entire structure. Neo- is the same as Iso- with respect to naming a s...
by Preston_Dang_1B
Tue Feb 28, 2017 4:08 pm
Forum: *Alkanes
Topic: 4-ethyl-2,2-dimethylhexane vs 2,2-dimethyl-4-ethylhexane
Replies: 2
Views: 517

Re: 4-ethyl-2,2-dimethylhexane vs 2,2-dimethyl-4-ethylhexane

The order is based on the first letter of the individual substituents regardless of the prefix in front. In other words, for dimethyl, it is the "m" that is ordered and not the "d." Therefore, ethyl would be written before methyl in the naming of the compound rather than the othe...
by Preston_Dang_1B
Thu Feb 23, 2017 11:42 pm
Forum: *Electrophiles
Topic: BF3
Replies: 2
Views: 361

Re: BF3

Yes because the central Boron atom in molecule only has 6 electrons and would want to complete its octet, so therefore it would be an electrophile.
by Preston_Dang_1B
Tue Feb 14, 2017 12:41 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: 14.85
Replies: 1
Views: 189

Re: 14.85

This is because reducing power is the ability of an element to cause another element to be reduced, in other words, it is asking for the best reducing agent out of all of the elements listed. This means that the element that has the lowest reduction potential would have the higher reducing power bec...
by Preston_Dang_1B
Sun Feb 12, 2017 10:40 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Ssurroudnings vs Ssystem
Replies: 1
Views: 208

Re: Ssurroudnings vs Ssystem

You would add the negative sign relative to which \Delta S you are looking at. For example, if you were looking at \Delta S surr and the reaction taking place is endothermic, then that means heat is being lost from the surroundings and going into the system, which means that the surroundings are los...
by Preston_Dang_1B
Sun Feb 12, 2017 10:35 am
Forum: Balancing Redox Reactions
Topic: Adding H20 AND H+
Replies: 3
Views: 341

Re: Adding H20 AND H+

You add H2O molecules to a half reaction to help balance out the number of oxygens each side of the reaction has. Similarly, you would add H+ ions to help balance out the number of hydrogens there are on each side of the equation.

Hope this helps!
by Preston_Dang_1B
Sun Feb 05, 2017 10:13 pm
Forum: Balancing Redox Reactions
Topic: Oxidation [ENDORSED]
Replies: 4
Views: 658

Re: Oxidation [ENDORSED]

The oxidizing agent of a reaction is the element that receives the electron(s) that are lost by the element that is being oxidized in the reaction. In other words, it is the element that is being reduced in the reaction. As for the reducing agent, it's the exact opposite. It is the element that give...
by Preston_Dang_1B
Fri Feb 03, 2017 11:37 pm
Forum: Balancing Redox Reactions
Topic: Standard reduction potential (E)
Replies: 2
Views: 372

Re: Standard reduction potential (E)

It'll vary depending on the situation. The cathode/anode of a reaction depends whether or not the elements in a reaction are reduced or oxidized, respectively. It's not always a given that the cathode half-reaction will be positive and the anode negative.
by Preston_Dang_1B
Fri Jan 27, 2017 5:54 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Enthalpy Units
Replies: 1
Views: 238

Re: Enthalpy Units

When the units are just kJ, it usually is written at the end of a reaction on the same line and it's implied that value of enthalpy is the change in energy for one "mole" of reaction. For example, if you were to double the amount of reactants/products, it would use twice the amount of enth...
by Preston_Dang_1B
Wed Jan 11, 2017 7:08 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Ch.8 Exercise 31
Replies: 2
Views: 250

Re: Ch.8 Exercise 31

You will need to use the q=mc\Delta T equation and plug in the values you are given, the mass, heat capacity constant for Krypton, and the change in temperature. The reason for there being two different heat capacities is because the heat capacity constant for any substance is different depending on...
by Preston_Dang_1B
Wed Nov 30, 2016 5:03 pm
Forum: *Indicators
Topic: Importance of Indicators
Replies: 2
Views: 2205

Re: Importance of Indicators

The main thing about indicators is that they cause the solution you are titrating to change color when you reach the stoichiometric point of a titration. There's a bunch of different indicators with different pK ln values and you have to strategically select an indicator that has a pK In value that ...
by Preston_Dang_1B
Mon Nov 21, 2016 5:49 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Why when given Ka = weak acid
Replies: 7
Views: 809

Re: Why when given Ka = weak acid

This is because the K a is an equilibrium constant for the dissociation of the acid in water. If you're given any value of K a , then that means not all of the acid has dissociated when the acid placed in water and there are still molecules of the acid inside of the water, along with some small conc...
by Preston_Dang_1B
Wed Nov 16, 2016 7:07 pm
Forum: Lewis Acids & Bases
Topic: question regarding lecture today
Replies: 1
Views: 316

Re: question regarding lecture today

We won't see the equilibrium constant because HCl dissociates completely in water, meaning that all of the HCl "splits" into H + and Cl - and therefore there won't be any HCl molecules left in the water after the reaction is finished. Therefore, there won't be any reactants left and the eq...
by Preston_Dang_1B
Tue Nov 15, 2016 5:20 pm
Forum: Naming
Topic: Number 29 from the Hw [ENDORSED]
Replies: 4
Views: 397

Re: Number 29 from the Hw [ENDORSED]

Woops my bad, it would be ferrate because the overall charge on the compound is negative so you would add the -ate ending on the metal to reflect that.
by Preston_Dang_1B
Sun Nov 06, 2016 7:56 pm
Forum: Naming
Topic: Number 29 from the Hw [ENDORSED]
Replies: 4
Views: 397

Re: Number 29 from the Hw [ENDORSED]

Finding the oxidation number of metals is generally pretty straightforward as you would just subtract the overall charge of the compound by any negatively charged ligands located between the brackets (for the iron compound, there are 6 CN - molecules so subtract that from -4 gives a 2+ charge for th...
by Preston_Dang_1B
Thu Oct 27, 2016 8:00 pm
Forum: Hybridization
Topic: 5 bonds - sp3d??? [ENDORSED]
Replies: 2
Views: 594

Re: 5 bonds - sp3d??? [ENDORSED]

This is because there are only 3 different p "sub-orbitals" (p x , p y , p z ) and when all three hybridize with an s orbital, the highest number of hybrid orbitals that can be produced is four, meaning that the four hybrid orbitals can only support a molecule that has four regions of elec...
by Preston_Dang_1B
Sun Oct 23, 2016 1:17 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Textbook question 3.5
Replies: 1
Views: 292

Re: Textbook question 3.5

This is because copper's electron configuration is special in that it takes one of the electrons from its 4s orbital and moves it to its 3d orbital so that the 3d orbital contains 10 electrons and is therefore in a more stable configuration. As a result, the configuration of copper is [Ar]3d 10 4s 1...
by Preston_Dang_1B
Thu Oct 13, 2016 11:21 am
Forum: Molarity, Solutions, Dilutions
Topic: Workbook Page 11 Number 5
Replies: 2
Views: 423

Re: Workbook Page 11 Number 5

The placement of the period is a little bit off in the equation. The dot is meant to be a little higher up and in between Copper(II) Sulfate and 5 Water and is meant to be a sort of "multiplication dot" that indicates that the compound is a type of hydrate, hence the additional 5 water mol...
by Preston_Dang_1B
Wed Oct 05, 2016 4:04 pm
Forum: Properties of Light
Topic: 1.69 Homework Problem [ENDORSED]
Replies: 2
Views: 505

Re: 1.69 Homework Problem [ENDORSED]

The agents have to choose the laser that best mimics the original laser in regards to it being able to discharge electrons from the surface of the lithium cell. This is because if the beam is broken or if the laser has less energy than the original one, the alarm will go off (indicating that no elec...
by Preston_Dang_1B
Fri Sep 30, 2016 4:25 pm
Forum: Properties of Light
Topic: Magnetic and Electric fields
Replies: 4
Views: 425

Re: Magnetic and Electric fields

I think it's referring to the electric field.
by Preston_Dang_1B
Fri Sep 30, 2016 4:24 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: 1.57 [ENDORSED]
Replies: 5
Views: 894

Re: 1.57 [ENDORSED]

The wavelengths listed correspond to the different wavelengths an electron can absorb at each energy level (i.e. 653.6 nm for n = 1, 486.1 for n = 2, etc.). Since it's asking for the next wavelength in the series, you would need to find the energy difference of the electron at n = 5 since you're giv...

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