Search found 102 matches
- Sat Mar 14, 2020 5:31 pm
- Forum: Second Order Reactions
- Topic: Finding out order
- Replies: 22
- Views: 1058
Re: Finding out order
For each different order, the rate constant will have its own units. If you can determine the units that the constant has, you can deduce the reaction order.
- Sat Mar 14, 2020 5:26 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Steps to solve calorimeter problem
- Replies: 3
- Views: 981
Re: Steps to solve calorimeter problem
q=mcdeltaT should be used to solve these problems. Remember to take into account phase shifts as well, as they take up a significant portion of the heat energy needed to heat up a substance.
- Sat Mar 14, 2020 5:24 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: What was your favorite chem topic?
- Replies: 137
- Views: 11597
Re: What was your favorite chem topic?
I loved Chemical Equilibrium! I thought it was pretty straightforward and for some reason I found it fun to imagine how equations would shift around depending on the reactant/product concentrations.
- Sat Mar 14, 2020 5:23 pm
- Forum: Zero Order Reactions
- Topic: Example Help
- Replies: 6
- Views: 598
Re: Example Help
In a zero order reaction, the rate of the reaction does NOT depend of the concentration of the reactant; the rate remains constant throughout the entire reaction.
- Sat Mar 14, 2020 5:19 pm
- Forum: Administrative Questions and Class Announcements
- Topic: take home FINAL DEADLINE
- Replies: 15
- Views: 1134
Re: take home FINAL DEADLINE
There was an e-mail that just got sent saying it would be 3 and a half hours from 11:15 AM to 2:45 PM.
- Sun Mar 08, 2020 9:32 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Exothermic vs. Endothermic
- Replies: 10
- Views: 1904
Re: Exothermic vs. Endothermic
All reactions will have some sort of activation energy. What determines if a reaction is exothermic or endothermic is the final value of the amount of energy still within the system.
- Sun Mar 08, 2020 9:30 pm
- Forum: Balancing Redox Reactions
- Topic: e- amount
- Replies: 9
- Views: 663
Re: e- amount
To cancel out the electrons, multiply the half-reactions to get equal amounts of electrons on both sides and then add the reactions together.
- Sun Mar 08, 2020 9:15 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: Equations
- Replies: 8
- Views: 575
Re: Equations
By using these two equations, we can set both of them equal to each other, and manipulate them to derive the Van't Hoff Equation.
- Sun Mar 08, 2020 9:07 pm
- Forum: Zero Order Reactions
- Topic: Zero Order Rxn
- Replies: 7
- Views: 872
Re: Zero Order Rxn
Yes, Zero-Order Reactions depend solely on the rate constant, and do not involve any other factors.
- Sun Mar 08, 2020 9:06 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Molecularity
- Replies: 12
- Views: 834
Re: Molecularity
Molecularity is number of particles as a reactant that participate in a reaction.
One - unimolecular
Two - bimolecular
Three - termolecular
One - unimolecular
Two - bimolecular
Three - termolecular
- Sun Mar 01, 2020 9:50 pm
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: when to use K or Q
- Replies: 18
- Views: 1117
Re: when to use K or Q
K values are used when the reaction is currently in equilibrium. However, if the reaction is not in equilibrium, the value Q is used instead.
- Sun Mar 01, 2020 9:49 pm
- Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
- Topic: electrolysis
- Replies: 6
- Views: 484
Re: electrolysis
Yes. The electrolysis supplies the external energy that can be used to drive a non spontaneous reaction.
- Sun Mar 01, 2020 9:48 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: cell potential
- Replies: 15
- Views: 830
Re: cell potential
When E is positive, the reaction will be spontaneous. However, when E is negative, the reaction will be nonspontaneous.
- Sun Mar 01, 2020 9:47 pm
- Forum: Balancing Redox Reactions
- Topic: Acidic and Basic Reactions
- Replies: 9
- Views: 523
Re: Acidic and Basic Reactions
OH- and H+ are used to balance basic and acidic reactions in half reactions, respectively.
- Sun Mar 01, 2020 9:28 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Kelvin or Celsius?
- Replies: 86
- Views: 5900
Re: Kelvin or Celsius?
You will almost always be using Kelvin in equations and calculations; in terms of the gas constant, it is measured in Kelvin rather than Celsius.
- Sun Feb 23, 2020 11:43 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: applying gibbs free energy
- Replies: 5
- Views: 435
Re: applying gibbs free energy
Gibbs free energy allows us to determine if an equation is spontaneous or not.
- Sun Feb 23, 2020 11:41 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Negative work
- Replies: 14
- Views: 958
Re: Negative work
Work, as viewed through the lenses of chemistry, is positive when it is being done ON the system. Therefore, work is negative when the system itself is doing work on the surroundings.
- Sun Feb 23, 2020 11:40 pm
- Forum: Balancing Redox Reactions
- Topic: Test 2 Topics
- Replies: 7
- Views: 515
Re: Test 2 Topics
Test 2 will include the second page of Thermodynamics and the entirety of electrochemistry!
- Sun Feb 23, 2020 11:39 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Test #1 Problem #2
- Replies: 2
- Views: 319
Re: Test #1 Problem #2
With these initial concentrations and the Kc value, you are able to determine which way the reaction shifts by calculating Q. Form there, compare Q to Kc to determine the reaction direction.
- Sun Feb 23, 2020 11:37 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Adding Inert Gas
- Replies: 20
- Views: 1135
Re: Adding Inert Gas
Because inert gases are not technically a part of the equation, they have no effect on the reaction equilibrium.
- Sun Feb 16, 2020 8:19 pm
- Forum: Balancing Redox Reactions
- Topic: easier to split?
- Replies: 6
- Views: 468
Re: easier to split?
To better understand the process of a redox reaction, it is recommended to split the reaction into an oxidation and reduction reaction. This lets us identify which species is oxidized and reduced, and also allows us to balance the redox reaction via the electrons.
- Sun Feb 16, 2020 7:43 pm
- Forum: Balancing Redox Reactions
- Topic: Reduction vs. oxidation
- Replies: 29
- Views: 1212
Re: Reduction vs. oxidation
Species that gain electrons are considered reduced, while species that lose electrons are oxidized.
- Sun Feb 16, 2020 7:01 pm
- Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
- Topic: Isobaric systems
- Replies: 16
- Views: 851
Re: Isobaric systems
Isobaric means constant pressure. Isochoric means constant volume. Isothermal means constant temperature.
- Sun Feb 16, 2020 7:00 pm
- Forum: Ideal Gases
- Topic: reversing reactions
- Replies: 83
- Views: 5585
Re: reversing reactions
The value of K in a reverse reaction is the inverse of the forward reaction. If the value of K in a forward reaction is K, then the equilibrium constant in the reverse reaction is 1/K.
- Wed Feb 12, 2020 4:13 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Pizza Rolls REVIEW Session DOWNLOAD HERE
- Replies: 67
- Views: 5867
Re: Pizza Rolls REVIEW Session DOWNLOAD HERE
Can someone explain 2 D? For some reason I'm not getting the right answer for the reaction quotient :( For 2D, remember that NH4HS(s) is not included in the reaction quotient, since it is a solid! The equation should just be Q = [H2S][NH3]! Make sure to convert the mols into MOLAR by dividing the m...
- Sun Feb 09, 2020 5:02 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Textbook question 4B.9
- Replies: 4
- Views: 187
Re: Textbook question 4B.9
In adiabatic processes, heat is not transferred in or out of a system. Therefore, q is equal to 0, allowing us to determine w (work) from inference and deductions.
- Sun Feb 09, 2020 4:58 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Closed Systems
- Replies: 13
- Views: 718
Re: Closed Systems
Closed systems will block the transfer of matter in and out of the system, but still permits the transfer of energy inside and outside of the system.
- Sun Feb 09, 2020 4:51 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Topics on the Midterm
- Replies: 22
- Views: 1149
Re: Topics on the Midterm
The midterm will cover Outlines 1 to the first page of Outline 4!
- Sun Feb 09, 2020 4:46 pm
- Forum: Phase Changes & Related Calculations
- Topic: Homework Problem 4C.13
- Replies: 3
- Views: 188
Re: Homework Problem 4C.13
The problem asks for us to convert 0 degrees C ice into 45 degrees water. However, to do this, we need to melt the ice into water, which requires us to use the enthalpy of formation and a phase shift calculation. After that, we can calculate the energy required to heat 0 degrees water to 45 degrees ...
- Sun Feb 09, 2020 4:34 pm
- Forum: Phase Changes & Related Calculations
- Topic: Difference in energy needed for the different phases
- Replies: 3
- Views: 187
Re: Difference in energy needed for the different phases
Vaporization requires significantly more energy to completely break the hydrogen bonds between the H2O molecules, rather than just slightly mobilising the water molecules by melting it from solid to liquid.
- Sun Feb 02, 2020 10:08 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Shifts
- Replies: 6
- Views: 434
Re: Shifts
There are multiple different ways an equilibrium can shift- if reactants are added to a reaction, the reaction will naturally want to balance itself to fit the reaction constant and thus will create more products. The same applies vice-versa.
- Sun Feb 02, 2020 10:06 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1 #6
- Replies: 6
- Views: 367
Re: Test 1 #6
HF is actually not a strong acid, since fluoride is so electronegative that it does not want to dissociate in water. As a result, it does not have 100% ionization.
- Sun Feb 02, 2020 10:05 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Test 1
- Replies: 6
- Views: 255
Re: Test 1
When Q is greater than K, the reaction will shift to the left. When Q is lower than K, the reaction will shift to the right.
- Sun Feb 02, 2020 9:48 pm
- Forum: Student Social/Study Group
- Topic: Post All Chemistry Jokes Here
- Replies: 9651
- Views: 3666296
Re: Post All Chemistry Jokes Here
Polar bears are unable to swim in water- they dissolve when they jump in.
- Sun Feb 02, 2020 9:46 pm
- Forum: Thermodynamic Systems (Open, Closed, Isolated)
- Topic: Identifying
- Replies: 4
- Views: 1137
Re: Identifying
Identifying different types of systems allows you to understand how the flow of energy is moving and determine how to calculate reaction energy; for example, it is extremely difficult to determine the heat lost or gained in an open calorimetry system.
- Sun Jan 26, 2020 10:44 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: The 3 methods
- Replies: 4
- Views: 158
Re: The 3 methods
Using bond enthalpies is going to be the least accurate, since bond enthalpies are found from an average of multiple different molecules.
- Sun Jan 26, 2020 10:43 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Water Phase Change
- Replies: 6
- Views: 190
Re: Water Phase Change
Because the molecules of water are held together by hydrogen bonding, it takes a large amount of energy to break those bonds and change its phase; this energy is reflected in the gas phase with its high kinetic energy
- Sun Jan 26, 2020 10:38 pm
- Forum: Phase Changes & Related Calculations
- Topic: Hess's Law
- Replies: 8
- Views: 211
Re: Hess's Law
Hess' Law states that the total enthalpy change of a reaction is the sum of all the individual changes within the reaction!
- Sun Jan 26, 2020 10:25 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Exothermic reaction
- Replies: 18
- Views: 737
Re: Exothermic reaction
In an exothermic reaction, because the heat is technically treated as a "product", increasing the temperature would cause the reaction to shift towards the left.
- Sun Jan 26, 2020 10:24 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Midterm
- Replies: 8
- Views: 340
Re: Midterm
The Midterm is on Feb 12th on Wednesday!
- Sun Jan 19, 2020 9:25 pm
- Forum: Ideal Gases
- Topic: Topics on Test 1
- Replies: 37
- Views: 1413
Re: Topics on Test 1
According to my TA, we should know:
1. Chemical equilibrium constant
2. ICE table
3. Le Chatelier’s Principle
4. Ideal Gas Law
5. Equilibrium for weak acid, base, pH calculation, quadratic equations.
6. Manipulations of Kc
Hope this helps!
1. Chemical equilibrium constant
2. ICE table
3. Le Chatelier’s Principle
4. Ideal Gas Law
5. Equilibrium for weak acid, base, pH calculation, quadratic equations.
6. Manipulations of Kc
Hope this helps!
- Sun Jan 19, 2020 9:19 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: 5J.1
- Replies: 4
- Views: 248
Re: 5J.1
In order to balance the equilibrium, as the partial pressure of CO is decreased, the partial pressure of CO2 must decrease as well and will shift to the left.
- Sun Jan 19, 2020 9:17 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Not including solids and liquids
- Replies: 7
- Views: 306
Re: Not including solids and liquids
Solids and liquids do not affect the equilibrium in any significant way, and are not measured in concentrations; as a result, they are left out in K value calculations.
- Sun Jan 19, 2020 9:10 pm
- Forum: Ideal Gases
- Topic: When to use PV=nRT
- Replies: 5
- Views: 174
Re: When to use PV=nRT
Ideal gas law is used to convert individual concentrations into partial pressures, and vise-versa. It's useful for expressing K in either Kc (concentration) or Kp (partial pressure).
- Sun Jan 19, 2020 9:09 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Exo/Endo-thermic Rxns
- Replies: 5
- Views: 297
Re: Exo/Endo-thermic Rxns
I'm not 100% sure I understand the question, but relating to chemical equilibrium, Exothermic reactions will have heat as a "product" as they release heat during their reaction, while Endothermic reactions will have heat as a "reactant" as it absorbs heat during the reaction. Thi...
- Sun Jan 12, 2020 8:25 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Q and K
- Replies: 6
- Views: 407
Re: Q and K
K is a constant that is calculated during equilibrium, but Q is the reactant quotient that is not calculated during equilibrium. Q is a good indicator of which way a reactant will be favored; if its less than K, then the reaction is favored forwards, and vice-versa.
- Sun Jan 12, 2020 8:22 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Units for K
- Replies: 21
- Views: 673
Re: Units for K
K does not have any units associated with it, since it's just a ratio of different molecules and species.
- Sun Jan 12, 2020 8:21 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: K and Q
- Replies: 10
- Views: 314
Re: K and Q
K is calculated when the reaction is at equilibrium, but Q is not. Q is a great indicator to figure out which way the reaction is favored.
- Sun Jan 12, 2020 8:18 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp
- Replies: 6
- Views: 425
Re: Kp
Kp is only used for gases, while Kc is used for concentrations. If needed, you can convert individual species from concentration to atm through PV=nRT
- Sun Jan 12, 2020 8:17 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Studying tips
- Replies: 10
- Views: 506
Re: Studying tips
Hey! Here's some things that worked for me last quarter; Doing every single hw problem on the syllabus. They're all fantastic review of concepts and things that will be on the test, and some problems will be the exact same on these tests, midterms, and finals. Visiting chem community and browsing th...
- Mon Dec 02, 2019 5:34 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: 9C.9
- Replies: 1
- Views: 118
Re: 9C.9
It’s best to use the table they have in the textbook! For c, each Cl has one bonding site, so that would be 2. Each (en) has two bonding sites, and since there are 2, there would be 4 (en) bonding sites in total. All in all, that would be 6! For d, (edta) has a total of sic potential bonding sites, ...
- Mon Dec 02, 2019 8:18 am
- Forum: Administrative Questions and Class Announcements
- Topic: Calculators on Final
- Replies: 6
- Views: 387
Re: Calculators on Final
I’m pretty certain we’ll need calculators, since it’ll be based on some topics we covered on the midterm as well.
- Mon Dec 02, 2019 8:16 am
- Forum: Properties & Structures of Inorganic & Organic Acids
- Topic: Lecture
- Replies: 3
- Views: 331
Re: Lecture
The more stable an acid’s structure is, the stronger it usually is because of how it will run to full completion rather than the reaction being partially completed. The more electronegative atoms attached or the more resonance structures, the more stable these acids are.
- Mon Dec 02, 2019 8:12 am
- Forum: Industrial Examples
- Topic: What do we need to know?
- Replies: 15
- Views: 1619
Re: What do we need to know?
I think it’d be good to review the general structure and the different things he notes about it; for hemoglobin I remember Prof. Lavelle talked quite a bit about oxygen and iron within hemoglobin.
Re: oxidation
For transition metals, the oxidation number is an important part of the naming process with a Roman numeral indicating the oxidation state being placed after the transition metal.
- Mon Dec 02, 2019 8:07 am
- Forum: Naming
- Topic: Order of Ligands
- Replies: 4
- Views: 298
Re: Order of Ligands
Ligands should be named in alphabetical order, but ignore the prefixes when you’re arranging them!
- Mon Dec 02, 2019 8:05 am
- Forum: Biological Examples
- Topic: How Cisplatin Works?
- Replies: 2
- Views: 142
Re: How Cisplatin Works?
Cisplatin’s ligands are able to bind to the nucleotides of DNA on two sites, while transplatin can only do so on one site.
- Mon Dec 02, 2019 8:02 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Test 2
- Replies: 6
- Views: 515
Re: Test 2
I already had my test handed back, so you should get it by your discussion date or it’ll be posted online!
- Mon Dec 02, 2019 7:59 am
- Forum: Hybridization
- Topic: 2F.5
- Replies: 4
- Views: 372
Re: 2F.5
Hybridization cam be found relatively straightforward by drawing out the lewis structures for each molecule!
- Mon Dec 02, 2019 7:57 am
- Forum: SI Units, Unit Conversions
- Topic: midterm/final
- Replies: 18
- Views: 1503
Re: midterm/final
It’ll more than likely be a mix of the two, with an emphasis on calculations and some conceptual understanding as well.
- Mon Dec 02, 2019 7:46 am
- Forum: Administrative Questions and Class Announcements
- Topic: Curving in Chem 14A
- Replies: 7
- Views: 594
Re: Curving in Chem 14A
There is a chance for a slight curve, but it’s not large enough for us to bank on it.
- Sun Nov 17, 2019 6:05 pm
- Forum: Lewis Structures
- Topic: Exceptions
- Replies: 5
- Views: 199
Re: Exceptions
Elements that are in the third period and lower are able to draw upon their other subshells and thus can break the octet "rule". There are also other elements that break it by not fully filling their shells to 8 as well!
- Sun Nov 17, 2019 6:00 pm
- Forum: DeBroglie Equation
- Topic: When to Use
- Replies: 8
- Views: 518
Re: When to Use
This equation is only to find the wavelength for objects with mass, velocity, and thus momentum! It will NOT work for electromagnetic radiation, so be sure to not confuse it with c = (frequency)(wavelength).
- Sun Nov 17, 2019 5:58 pm
- Forum: SI Units, Unit Conversions
- Topic: Memorizing Conversions
- Replies: 25
- Views: 1378
Re: Memorizing Conversions
I've found it really useful to know micro, nano, pico, Angstroms, kilo, milli, and centi off the top of my head, but the exam provides the conversions if you forget as well!
- Sun Nov 17, 2019 5:57 pm
- Forum: Trends in The Periodic Table
- Topic: Question
- Replies: 17
- Views: 1421
Re: Question
They're somewhat related, but they're not the same!
Ionization energy is the amount of energy required to remove an electron from the atom, while electronegativity is how much an atom attracts electrons towards it!
Ionization energy is the amount of energy required to remove an electron from the atom, while electronegativity is how much an atom attracts electrons towards it!
- Sun Nov 17, 2019 5:40 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR
- Replies: 5
- Views: 329
Re: VSEPR
There's no set formula for VSEPR, but the general format for for the structures is AXnEn (A is the central atom, X is any atom around the central atom, and E is the electron lone pairs surrounding the electron).
- Sun Nov 10, 2019 11:44 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Quantum numbers
- Replies: 12
- Views: 777
Re: Quantum numbers
The angular momentum is l, n is the principle quantum number, m(l) is the magnetic quantum number, and m(s) is the electron spin number.
- Sun Nov 10, 2019 11:40 pm
- Forum: DeBroglie Equation
- Topic: De Broglie Equation Derivation and Use
- Replies: 7
- Views: 1182
Re: De Broglie Equation Derivation and Use
De Broglie's equation can be used for any particle or object with a mass and velocity (momentum)!
- Sun Nov 10, 2019 11:39 pm
- Forum: Properties of Light
- Topic: How to find the longest wavelength?
- Replies: 6
- Views: 4686
Re: How to find the longest wavelength?
The longest wavelength correlates with the same amount of energy of the work function. Just set Ep and the Work Function equal to one another and solve for the wavelength!
- Sun Nov 10, 2019 11:29 pm
- Forum: Trends in The Periodic Table
- Topic: Electronegativity
- Replies: 9
- Views: 519
Re: Electronegativity
Electronegativity will increase moving up the periodic table, and also increase going from left to right each period!
- Sun Nov 10, 2019 11:28 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radius
- Replies: 30
- Views: 3146
Re: Atomic Radius
Atomic radius will increase as you go down the periodic table, and will also increase as you move from right to left each period!
- Sun Nov 03, 2019 11:24 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: magnetic quantum number
- Replies: 5
- Views: 208
Re: magnetic quantum number
The magnetic quantum number describes the specific orbital within the shell and the shell shape. It correlates with the orbital quantum number, ranging from -l to +l. This image might be useful to help visualise what's being described by the number. I hope this helps! https://upload.wikimedia.org/wi...
- Sun Nov 03, 2019 11:17 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Aufbau vs Hunds
- Replies: 6
- Views: 515
Re: Aufbau vs Hunds
The Aufbau principle is that electrons need to first occupy the lower energy levels before filling higher energy ones- it literally means "build-up" in German! Hund's rule says that the orbitals need to have one electron first before they can be paired up with another electron.
- Sun Nov 03, 2019 11:14 pm
- Forum: Trends in The Periodic Table
- Topic: Dino Nugget Mini review
- Replies: 3
- Views: 236
Re: Dino Nugget Mini review
Polarizing power is related to the charge over the size of the ion; Lithium would have the most polarizing power, as it as the smallest radius out of all the cations listed.
- Sun Nov 03, 2019 11:06 pm
- Forum: Properties of Light
- Topic: De Broglie
- Replies: 3
- Views: 166
Re: De Broglie
Electrons will have a faster velocity than the protons. Because the wavelengths are the same, and electrons are significantly smaller than protons, the electrons' velocity will be faster than the protons'.
- Sun Nov 03, 2019 11:03 pm
- Forum: Properties of Light
- Topic: What are the units of hertz
- Replies: 41
- Views: 2152
Re: What are the units of hertz
s^-1, or one cycle per second!
- Sun Oct 27, 2019 11:52 pm
- Forum: Wave Functions and s-, p-, d-, f- Orbitals
- Topic: Octet Rules
- Replies: 8
- Views: 565
Re: Octet Rules
Just to add on, other elements like sulfur, silicon, and chlorine can have expanded octets!
- Sun Oct 27, 2019 11:49 pm
- Forum: SI Units, Unit Conversions
- Topic: Calculate using kg or g?
- Replies: 13
- Views: 898
Re: Calculate using kg or g?
It'll depend mostly on the equation that you need to use, but generally we use grams for molar conversions and kilograms for calculations involving spectrography.
- Sun Oct 27, 2019 11:47 pm
- Forum: Significant Figures
- Topic: Sig Figs on Tests
- Replies: 24
- Views: 2254
Re: Sig Figs on Tests
Your answer should have the same amount of sig figs as the lowest sig fig number given in the problem!
- Sun Oct 27, 2019 11:46 pm
- Forum: Significant Figures
- Topic: How many significant figures are in 7.00 x 10^2?
- Replies: 25
- Views: 3623
Re: How many significant figures are in 7.00 x 10^2?
There'd be only 3 sig figs! We don't consider the power in the scientific notion, only the 7.00. Going by that, there would be 3, one before the decimal, and one after.
- Sun Oct 27, 2019 11:45 pm
- Forum: SI Units, Unit Conversions
- Topic: Midterm
- Replies: 6
- Views: 360
Re: Midterm
Yes, the midterm is going to cover everything we've learned up to now. It'd be good to go over all of our homework to review for it!
- Sun Oct 20, 2019 11:45 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: What is Molarity?
- Replies: 11
- Views: 1053
Re: What is Molarity?
Molarity refers to the amount of moles of solute over the liters of the solvent. For example, 3 moles of NaCl in a single liter of water would be a 3M solution of NaCl.
- Sun Oct 20, 2019 11:43 pm
- Forum: Empirical & Molecular Formulas
- Topic: Molecular to Empirical Formula
- Replies: 10
- Views: 996
Re: Molecular to Empirical Formula
To find the molecular formula, you'll need both the molecular mass and the mass of the empirical formula. Simply divide the molecular mass by the empirical mass, and you'll get the ratio you need to multiply the empirical formula by to find the molecular formula!
- Sun Oct 20, 2019 11:42 pm
- Forum: SI Units, Unit Conversions
- Topic: Accuracy vs Precision
- Replies: 11
- Views: 793
Re: Accuracy vs Precision
Accuracy reflects how close your measured values are to the true value, while precision reflects how close together your measurements were! Precision doesn't necessarily have to be close to the true value, just closely grouped together.
- Sun Oct 20, 2019 11:30 pm
- Forum: Significant Figures
- Topic: %Mass Composition
- Replies: 12
- Views: 789
Re: %Mass Composition
If there's no specification, I tend to round to 4 sig figs to keep it relatively precise and accurate; if there are sig figs listed or given in the problem, then just follow those standard conventions!
- Sun Oct 20, 2019 11:29 pm
- Forum: Balancing Chemical Reactions
- Topic: Balancing equations.
- Replies: 35
- Views: 2884
Re: Balancing equations.
It's always best to start with the more rare elements first when balancing, then steadily make your way to the more common ones like Oxygen or Hydrogen! It's also very handy to keep a registrar of sorts to keep track of the different element you have!
- Sun Oct 13, 2019 7:27 pm
- Forum: Significant Figures
- Topic: Sig Figs at the Beginning or End
- Replies: 14
- Views: 4877
Re: Sig Figs at the Beginning or End
Round to your sig figs at the very end of calculating; if you do it at the very beginning, your calculations will steadily grow more and more inaccurate because of all the rounding errors that compounded on each other. I like to keep really high amounts of precision with my early calculations so I c...
- Sun Oct 13, 2019 7:24 pm
- Forum: Balancing Chemical Reactions
- Topic: Any Easy Way
- Replies: 10
- Views: 601
Re: Any Easy Way
It definitely can get tedious, but I start with the least common or rarest element within the equation. Once you get these balanced, you usually won't have to go back and rebalance them in the future. Definitely leave Oxygen and Hydrogen for last- they can be really annoying to balance because of ho...
- Sun Oct 13, 2019 7:19 pm
- Forum: Empirical & Molecular Formulas
- Topic: Nomenclature
- Replies: 11
- Views: 2293
Re: Nomenclature
At this level of chemistry, a lot of the nomenclature will be provided to you in the question. I think as we go further in 14B, we'll need to start learning the actual names, formulas, and groups of molecules we see in questions.
- Sun Oct 13, 2019 7:13 pm
- Forum: Properties of Light
- Topic: Quanta- clear up comparison
- Replies: 3
- Views: 193
Re: Quanta- clear up comparison
On the macro scale, or on the scale where we usually view the world, the water flowing out of the bucket looks like it's flowing as a single continuous substance. However, when you zoom into the actual water, you'll see that the water as a whole is actual comprised of individual water molecules. Lik...
- Sun Oct 13, 2019 7:09 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Test 1 Grading
- Replies: 12
- Views: 966
Re: Test 1 Grading
I didn't realise we'd just get 10 points for taking the test, but my TA definitely said they'd give out partial credit whenever possible. It's definitely a good idea to just write down as much work as possible so they can award you for what you have.
- Sun Oct 13, 2019 7:07 pm
- Forum: Significant Figures
- Topic: Significant Figures on Test 1
- Replies: 3
- Views: 295
Re: Significant Figures on Test 1
My TA said that we shouldn't worry too much about sig figs! They might be graded lightly, if at all, but we should still know the basic rules behind them just in case.
- Sat Oct 05, 2019 12:35 pm
- Forum: Properties of Light
- Topic: Classical Mechanics vs. Quantum Mechanics
- Replies: 4
- Views: 118
Classical Mechanics vs. Quantum Mechanics
Could anybody help explain the differences between Classical Mechanics and Quantum Mechanics? I was a little bit confused by how the lecture example of water pouring out of a bucket could be modeled by both types of mechanics. Thanks!
- Sat Oct 05, 2019 12:32 pm
- Forum: Empirical & Molecular Formulas
- Topic: Empirical Formula Purpose
- Replies: 13
- Views: 3979
Re: Empirical Formula Purpose
Empirical formulas are useful to quickly determine the ratios of atoms in proportion to one another. Larger hydrocarbons, such as heptane (C6H14), can be reduced to a simpler ratio of C3H7. It's also widely used to represent ionic compounds (for example, CaCl2 or NaCl).
- Sat Oct 05, 2019 12:22 pm
- Forum: SI Units, Unit Conversions
- Topic: Homework for Week 1
- Replies: 16
- Views: 883
Re: Homework for Week 1
I think it should be fine to write in pencil! I've seen some people using one or the other, so it's probably up to personal preference- you should still talk to your TA just to confirm if he or she has any preference.
- Sat Oct 05, 2019 12:17 pm
- Forum: SI Units, Unit Conversions
- Topic: Homework
- Replies: 9
- Views: 511
Re: Homework
I do mine in pencil- I tend to make quite a few stray marks or errors in my work, so I like to be able to erase anything so I won't get lost in my train of thought!
- Sat Oct 05, 2019 12:12 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Use of Avogadro's number
- Replies: 3
- Views: 206
Re: Use of Avogadro's number
It's also good to distinguish specifically between Avogadro's number and Avogadro's constant! Avogadro's number is just the number 6.0221x10^23, and does not include any units. Avogadro's constant is Avogadro's number INCLUDING the units, measuring the amount of atoms, particles, molecules, or formu...
- Sat Sep 28, 2019 2:21 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Molar Mass
- Replies: 2
- Views: 223
Re: Molar Mass
For the problem, the main issue is to find the unknown metal in the metal hydroxide, M(OH)2. We already know the molar mass of the entire metal oxide is 74.10, so in order to find the molar mass of M, we need to subtract the masses of the two Hydroxide groups molar mass M = 74.10 g/mol - 34.02 g/mol...
- Sat Sep 28, 2019 2:08 pm
- Forum: Significant Figures
- Topic: Sig Figs on Molar Masses
- Replies: 4
- Views: 315
Re: Sig Figs on Molar Masses
Thanks! Also in regards to E.21B, the solutions manual rounded the moles of HF to 1.30x10-3 mol, but there were four sig figs in the problem (25.92 mg). Does anyone know why they would round the number to 3 sig figs instead?
- Sat Sep 28, 2019 1:59 pm
- Forum: Administrative Questions and Class Announcements
- Topic: Formatting homework
- Replies: 12
- Views: 658
Re: Formatting homework
I'm using binder paper as well. Does anybody know if we need headers indicating our discussion or lecture at the top?