Search found 76 matches
- Sat Feb 29, 2020 4:48 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: spontaneity
- Replies: 39
- Views: 1934
Re: spontaneity
when delta g is negative, the reaction is spontaneous and vice versa with positivity.
- Fri Feb 28, 2020 4:17 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Spontaneity
- Replies: 12
- Views: 947
Spontaneity
What determines whether a reaction is spontaneous or not? Is it based on whether the change in molar Gibbs free energy is positive or negative?
- Sun Feb 16, 2020 7:04 pm
- Forum: Balancing Redox Reactions
- Topic: Memorizing charges
- Replies: 11
- Views: 732
Re: Memorizing charges
We should just know the patterns of group 1 being 1+ group 2 +2 and 17 being -1 and 16 -2.
- Sun Feb 16, 2020 7:01 pm
- Forum: Van't Hoff Equation
- Topic: Van Hoff's Constants
- Replies: 6
- Views: 350
Re: Van Hoff's Constants
Delta H and Delta s are the constants.
- Sun Feb 16, 2020 7:00 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: q of ice and q of water
- Replies: 8
- Views: 1584
Re: q of ice and q of water
Because in the phase change heat lost from the water must equal the negative heat gained by the ice.
- Sun Feb 16, 2020 6:57 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Volume of the Universe
- Replies: 4
- Views: 276
Re: Volume of the Universe
Yes, the temperature of the universe does not change, so the change in entropy is the negative heat of the system minus heat of the surroundings.
- Sun Feb 16, 2020 6:53 pm
- Forum: Balancing Redox Reactions
- Topic: redox reaction
- Replies: 10
- Views: 586
Re: redox reaction
LEO is oxidized since it loses an electron and reduction is the opposite and an electron is gained.
- Sat Feb 08, 2020 9:00 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Adding Reactions
- Replies: 2
- Views: 187
Adding Reactions
When combining the equilibrium constant of two reaction, we multiple the constants, but how do we know when to square the coefficient or not as it does in example 5.H.2.
- Sat Feb 08, 2020 5:41 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: c naught and P naught
- Replies: 2
- Views: 1273
c naught and P naught
What do c naught and P naught stand for?
- Fri Feb 07, 2020 3:02 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: When to use Kp
- Replies: 2
- Views: 206
When to use Kp
Do we only use Kp when the reaction is a homogeneous equilibria of gas?
- Sun Feb 02, 2020 8:52 pm
- Forum: Ideal Gases
- Topic: PV=nRT
- Replies: 74
- Views: 4664
Re: PV=nRT
P is pressure, V is volume, n is the number of moles, R is Rydberg's gas constant, and T is temperature.
- Sun Feb 02, 2020 8:47 pm
- Forum: Phase Changes & Related Calculations
- Topic: Open vs Isolated System
- Replies: 15
- Views: 1322
Re: Open vs Isolated System
An isolated system has no contact to the surrounding environment while a closed system does but is not so affected by it.
- Sun Feb 02, 2020 8:44 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy of Rxn
- Replies: 9
- Views: 435
Re: Enthalpy of Rxn
you just multiply the enthalpy of the reaction by the moles to cancel out the reaction
- Sun Feb 02, 2020 8:31 pm
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Calorimeter vs. Bomb Calorimeter
- Replies: 4
- Views: 323
Re: Calorimeter vs. Bomb Calorimeter
A calorimeter has constant pressure while a bomb calorimeter has constant volume.
- Mon Jan 27, 2020 2:32 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Delta U
- Replies: 3
- Views: 335
Delta U
What does delta U stand for? Is it just the change in heat of the system?
- Sun Jan 26, 2020 5:22 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heat vs temperature
- Replies: 6
- Views: 358
Re: Heat vs temperature
temperature measures the amount warmth a sample has while heat measures the energy in a sample in kJ or Calories.
- Sun Jan 26, 2020 4:27 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase changes: endothermic vs exothermic
- Replies: 12
- Views: 1262
Re: Phase changes: endothermic vs exothermic
yes the reverse reaction, condensation, solidification, and deposition are all exothermic where they expel heat energy going from higher energy phases to lower energy phases.
- Sun Jan 26, 2020 4:24 pm
- Forum: Phase Changes & Related Calculations
- Topic: State property
- Replies: 6
- Views: 301
Re: State property
A state property is independent on how the quantity of the substance was prepared. Energy, pressure, volume, and temperature, density, and heat capacity are all state properties.
- Sun Jan 26, 2020 4:14 pm
- Forum: Phase Changes & Related Calculations
- Topic: Steam v. liquid
- Replies: 7
- Views: 288
Re: Steam v. liquid
Yes, the reason the steam causes more of a burn is since the steam undergoes a phase change on the skin, releasing 46kJ instead of the 5kJ released from hot water.
- Sun Jan 26, 2020 4:02 pm
- Forum: Phase Changes & Related Calculations
- Topic: phase changes
- Replies: 6
- Views: 267
Re: phase changes
The phase changes that are endothermic are vaporization( liquid to vapor), fusion (solid to liquid) which is also known as melting, and sublimation (solid to vapor) like dry ice. The reverse reactions of these phase changes will be exothermic.
- Sun Jan 19, 2020 3:45 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Concentrations
- Replies: 12
- Views: 414
Re: Concentrations
K is only affected by the concentration when measuring Kc instead of the K for partial pressure Kp.
- Sun Jan 19, 2020 3:43 pm
- Forum: Ideal Gases
- Topic: ICE Table
- Replies: 11
- Views: 840
Re: ICE Table
The I stands for initial concentration, the C stand for change in molar concentration, and the E stands for final concentration. You put the values for each of the reactants and products in a table usually 3x3.
- Sun Jan 19, 2020 3:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: pH values of weak and strong acids
- Replies: 6
- Views: 321
Re: pH values of weak and strong acids
Acids with higher pH levels take longer to dissociate, therefore they solution is less neutral. So overall stronger acids are easily broken down in a reaction compared to weak acids.
- Sun Jan 19, 2020 3:31 pm
- Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
- Topic: Exothermic and Endothermic Reactions
- Replies: 5
- Views: 309
Re: Exothermic and Endothermic Reactions
Negative delta H means the loss of energy, negative delta H reaction is endothermic since heat is required to instigate the reaction. Likewise, it goes for positive delta H and exothermic reactions.
- Sun Jan 19, 2020 3:19 pm
- Forum: *Titrations & Titration Calculations
- Topic: Acid/Base bonds
- Replies: 5
- Views: 885
Acid/Base bonds
Do weak acids have shorter or longer bonds? What determines if an acid is weak or strong?
- Sun Jan 12, 2020 9:04 pm
- Forum: Non-Equilibrium Conditions & The Reaction Quotient
- Topic: Partial Pressure
- Replies: 19
- Views: 748
Re: Partial Pressure
At least one quantity should be given in the problem, in order to solve for the rest of reactant and product pressures.
- Sun Jan 12, 2020 9:01 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Reaction Direction
- Replies: 19
- Views: 1033
Reaction Direction
How do we determine is the reaction is "left" or "right". And does the direction of the reaction matter if it is composition or decomposition?
- Sun Jan 12, 2020 8:40 pm
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Kp vs Kc usage
- Replies: 5
- Views: 192
Re: Kp vs Kc usage
Kp is used for partial pressure and (bar) while Kc is used for concentration with mol/L.
- Sun Jan 12, 2020 8:37 pm
- Forum: Ideal Gases
- Topic: Le Chatelier's Principle
- Replies: 7
- Views: 471
Re: Le Chatelier's Principle
Le Chatelier's principle is when chemical reactions adjust to minimize the effect of changes in the reaction. This is why, to increase the yield of the products without adding anymore reactants, we remove the products, disrupting the equilibrium.
- Sun Jan 12, 2020 8:32 pm
- Forum: Ideal Gases
- Topic: ICE Table
- Replies: 9
- Views: 520
ICE Table
Using the ICE tables, how do you know when the change in molar concentration is positive or negative?
- Sun Dec 08, 2019 9:34 pm
- Forum: Air Pollution & Acid Rain
- Topic: Options to reduce acid rain
- Replies: 8
- Views: 620
Re: Options to reduce acid rain
we can reduce burning of fossil fuels, which prevents the reaction of chlorofluorocarbons with ozone to produce acid rain.
- Sun Dec 08, 2019 9:33 pm
- Forum: Polyprotic Acids & Bases
- Topic: Amphiprotic vs Amphoteric
- Replies: 6
- Views: 617
Re: Amphiprotic vs Amphoteric
Any compound that is amphiprotic is amphoteric, however it is not true the other way around.
- Sun Dec 08, 2019 9:31 pm
- Forum: Electronegativity
- Topic: Noble Gases
- Replies: 40
- Views: 12783
Re: Noble Gases
Noble gases are not included in the electronegativity trend. In fact they are left out of most period trends.
- Sun Dec 08, 2019 9:30 pm
- Forum: *Black Body Radiation
- Topic: What is Black Body?
- Replies: 53
- Views: 2420
Re: What is Black Body?
What would it mean if we solved the black body dilemma, does that mean time travel.
- Sun Dec 08, 2019 9:29 pm
- Forum: *Shrodinger Equation
- Topic: effective nuclear charge
- Replies: 6
- Views: 684
Re: effective nuclear charge
Effective nuclear charge is whether the charge of the proton is positive or negative.
- Sun Dec 08, 2019 9:27 pm
- Forum: Significant Figures
- Topic: Sig Figs on Tests
- Replies: 24
- Views: 2243
Re: Sig Figs on Tests
3 significant values is the usual statistical value to complete calculations.
- Sun Dec 08, 2019 9:26 pm
- Forum: *Particle in a Box
- Topic: Hydrogen Atom
- Replies: 7
- Views: 1098
Re: Hydrogen Atom
The energy is positive since, the hydrogen atom absorbs energy.
- Sun Dec 08, 2019 9:24 pm
- Forum: Biological Examples
- Topic: heme group
- Replies: 4
- Views: 285
Re: heme group
a heme group is what allows myoglobin and hemoglobin to bind the Fe atom to oxygen.
- Sun Dec 08, 2019 9:21 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: n, l ,ml, ms
- Replies: 13
- Views: 1511
Re: n, l ,ml, ms
Up spin is +1/2 and down spin -1/2
- Sun Dec 08, 2019 9:16 pm
- Forum: Lewis Acids & Bases
- Topic: Mg(OH)2 Considered strong or weak base?
- Replies: 5
- Views: 3258
Re: Mg(OH)2 Considered strong or weak base?
Mg(OH)2 is definitely a strong base being a metal oxide with a group 1 metal.
- Sun Dec 08, 2019 9:14 pm
- Forum: Limiting Reactant Calculations
- Topic: A different way
- Replies: 8
- Views: 871
Re: A different way
This method is very efficient, but you can also compare the moles of the reactant and then use the ratio to compare limiting reactants.
- Sun Dec 08, 2019 12:34 am
- Forum: Limiting Reactant Calculations
- Topic: Oxidization
- Replies: 1
- Views: 236
Oxidization
What does it mean to oxidize a compound?
- Sun Nov 17, 2019 3:57 pm
- Forum: Ionic & Covalent Bonds
- Topic: London Dispersion
- Replies: 13
- Views: 682
Re: London Dispersion
what exactly is london dispersion?
- Sun Nov 17, 2019 3:55 pm
- Forum: Ionic & Covalent Bonds
- Topic: Bonds strength
- Replies: 4
- Views: 169
Re: Bonds strength
The double bond is stronger than a single bond since it is shorter, therefore having a lesser distance between each of the atoms. The shorter distance makes the bonds less likely to break than a short, single bond.
- Sun Nov 17, 2019 3:48 pm
- Forum: Bond Lengths & Energies
- Topic: Quiz for Next week dashes/wedges
- Replies: 11
- Views: 652
Re: Quiz for Next week dashes/wedges
What are the purpose of dashes and wedges, instead of making sure we don't indicate bonds instead of lone pairs and bond angles.
- Sun Nov 17, 2019 3:43 pm
- Forum: Bond Lengths & Energies
- Topic: Angle Distortion
- Replies: 4
- Views: 355
Angle Distortion
How do we know when a VSEPR model has a distortion like 106 degrees instead of the traditional 109.5 degrees for tetrahedral bonds.
- Sun Nov 17, 2019 3:39 pm
- Forum: Naming
- Topic: Cation/Anion
- Replies: 7
- Views: 860
Re: Cation/Anion
do we have to memorize the natural charges for each cation/ anion element, like 2+ or 1-
- Fri Nov 08, 2019 4:09 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radii
- Replies: 11
- Views: 746
Re: Atomic Radii
We can use atomic radii to determine the strength of the attraction of electrons to the atom compared how well the nucleus holds the electrons together.
- Fri Nov 08, 2019 4:06 pm
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Heisenberg
- Replies: 3
- Views: 246
Re: Heisenberg
Delta p is uncertain momentum and delta x is uncertain position. Delta p also means delta velocity multiplied by the constant mass.
- Fri Nov 08, 2019 3:30 pm
- Forum: Bond Lengths & Energies
- Topic: Sigma Pi
- Replies: 2
- Views: 176
Sigma Pi
Why are single bonds referred to as sigma bonds and double bonds as sigma pi and triple bonds as sigma pi pi?
- Fri Nov 08, 2019 3:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Difference between molecular and electron geometry?
- Replies: 3
- Views: 55959
Re: Difference between molecular and electron geometry?
How do we know when the structure doesn't have an ED and when it is just the molecular geometry?
- Fri Nov 08, 2019 3:27 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSPER
- Replies: 1
- Views: 100
VSPER
How do you know when to draw the "cloud" around a lone pair of electrons or when not to, according to the Lewis structure?
- Sun Nov 03, 2019 2:07 pm
- Forum: Bond Lengths & Energies
- Topic: Test?
- Replies: 8
- Views: 528
Re: Test?
Do we need to know how to calculate bond length for the midterm?
- Sun Nov 03, 2019 2:05 pm
- Forum: Polarisability of Anions, The Polarizing Power of Cations
- Topic: Polarizability
- Replies: 3
- Views: 256
Re: Polarizability
Polarizability is determined by whether the ion is an anion or cations. Generally, anions have polarizability while cations have polarizing power.
- Sun Nov 03, 2019 2:03 pm
- Forum: Dipole Moments
- Topic: Dipole moments
- Replies: 5
- Views: 320
Re: Dipole moments
How do we determine whether to place a positive or negative dipole moment in the Lewis structure and where to place them?
- Thu Oct 31, 2019 5:45 pm
- Forum: Ionic & Covalent Bonds
- Topic: Octet Rule
- Replies: 8
- Views: 334
Re: Octet Rule
Elements in the third period, S, P, and Cl are exceptions to the octet rules. For example, Sulfur is capable of making 6 bonds. This was shown in the example of SF6.
- Thu Oct 31, 2019 5:41 pm
- Forum: Ionic & Covalent Bonds
- Topic: Electronegativity
- Replies: 7
- Views: 277
Electronegativity
On the test do we have to know to know the electronegativity of elements?
Is there way to calculate the electronegativity of an element?
Is there way to calculate the electronegativity of an element?
- Sat Oct 26, 2019 3:27 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Formal Charge Formula
- Replies: 5
- Views: 307
Re: Formal Charge Formula
The term "shared electrons" means that two atoms have formed a covalent bond. If you can count the two shared electrons for filling both of the atom's outer shells, then they are shared. To count the shared electron, the two electron between two atoms count are "2". To determine ...
- Sat Oct 26, 2019 3:19 pm
- Forum: Lewis Structures
- Topic: Steps to drawing a structure
- Replies: 5
- Views: 223
Re: Steps to drawing a structure
Yes, the least electromagnetic atom must be able to hold the bonds with the other elements, therefore its placement in the center strengthens the entire compound.
- Mon Oct 21, 2019 4:03 pm
- Forum: Photoelectric Effect
- Topic: The Rydberg Formula and the Hydrogen Atomic Spectrum
- Replies: 4
- Views: 302
Re: The Rydberg Formula and the Hydrogen Atomic Spectrum
v = R {1/n1^2 - 1/n2^2}
In this equation for the book from the Rydberg equation, what do the series of n stand for? Of what "number" do they represent?
Thank you.
In this equation for the book from the Rydberg equation, what do the series of n stand for? Of what "number" do they represent?
Thank you.
- Mon Oct 21, 2019 3:55 pm
- Forum: Trends in The Periodic Table
- Topic: Neon
- Replies: 3
- Views: 141
Neon
When professor Lavelle was demonstrating isoelectronic atoms, through Na+, Mg2+, and F-, what was the significance of the element Neon?
Thank you
Thank you
- Sun Oct 20, 2019 1:58 pm
- Forum: Quantum Numbers and The H-Atom
- Topic: Electrons Spinning???
- Replies: 3
- Views: 151
Re: Electrons Spinning???
Electron spin is one of the two types of angular momentum in quantum mechanics and the other is orbital angular momentum. The electron's spin is a fixed, unvarying property such as charge and rest mass.
- Sun Oct 20, 2019 1:49 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Exceptions for Electron Configuration
- Replies: 6
- Views: 241
Re: Exceptions for Electron Configuration
For the exceptions, this is since half full d5 and full d10 subshells have lower energy. As an example he compared Titanium and Vanadium to Copper and Chromium.
- Sun Oct 20, 2019 1:43 pm
- Forum: Trends in The Periodic Table
- Topic: Atomic Radius
- Replies: 16
- Views: 953
Re: Atomic Radius
You should measure an atom's radius through the electron's ground state. The excited state of the electron should have no effect on measuring the atom's radius.
- Tue Oct 15, 2019 11:26 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Uncertainty Question
- Replies: 3
- Views: 157
Re: Uncertainty Question
In the example in lecture, the answer 3.4 x 10-10 m.s-1 was an unrealistic number for the uncertainty, since it was larger than the speed of light. How do we know when the velocity is an unrealistic number, will a probable speed always have to be lesser than 3.0 x 10-8?
Thank you.
Thank you.
- Tue Oct 15, 2019 11:21 am
- Forum: Heisenberg Indeterminacy (Uncertainty) Equation
- Topic: Indeterminacy Equation
- Replies: 5
- Views: 220
Re: Indeterminacy Equation
For the indeterminacy equation, why does the principle use delta p? What constitutes the change in position to use delta instead of regular p in the equation.
- Sun Oct 13, 2019 4:02 pm
- Forum: Properties of Electrons
- Topic: Electron Excitation
- Replies: 6
- Views: 330
Re: Electron Excitation
An electron being excited can also refer to the electron jumping from one orbital, usually its original, to another orbital further away from the nucleus. This results in a state of higher energy since the electrons absorbs energy.
- Sun Oct 13, 2019 3:54 pm
- Forum: Properties of Electrons
- Topic: Mass of Electrons
- Replies: 6
- Views: 305
Re: Mass of Electrons
The mass of an electron is always constant at 9.10938356 × 10-31 kilograms and corresponds to a resting energy of 0.115 MeV.
- Sun Oct 13, 2019 3:51 pm
- Forum: Properties of Light
- Topic: Intensity and Frequency
- Replies: 2
- Views: 118
Intensity and Frequency
When increasing the intensity of a wave does not lead to ejected electrons, the frequency of the light does. However what does it mean to increase the intensity of a wave rather than just the frequency of it?
Thank you.
Thank you.
- Sun Oct 13, 2019 3:45 pm
- Forum: Significant Figures
- Topic: How Many Sig Figs
- Replies: 7
- Views: 430
How Many Sig Figs
On tests and exams, when the amount of significant figures we are supposed to round to is not listed, how many should we normally put the answer in?
Thank you.
Thank you.
- Wed Oct 09, 2019 9:46 pm
- Forum: Properties of Light
- Topic: Work Function
- Replies: 3
- Views: 145
Work Function
Professor Lavelle always referred to the formulas as work functions, what exactly does that mean?
Thanks.
Thanks.
- Sun Oct 06, 2019 4:56 pm
- Forum: Balancing Chemical Reactions
- Topic: Net Ionic Equations, HW problem M9
- Replies: 1
- Views: 198
Re: Net Ionic Equations, HW problem M9
For net ionic reactions, you first need to balance the molecular equation. Then break all of the aqueous compounds into their compounds. Next, indicate the correct charge and number of each ion and write the formula with (aq) after the ions. Then bring down all the compounds with (l), (s), and (g).
- Sun Oct 06, 2019 4:41 pm
- Forum: Limiting Reactant Calculations
- Topic: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
- Replies: 68
- Views: 6977
Re: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
Yes, I believe we receive credit based on the correct answer, however the step by step problems in lecture are to understand the process of determining the limiting reagent.
- Fri Oct 04, 2019 1:17 pm
- Forum: Significant Figures
- Topic: When to round for sig figs?
- Replies: 12
- Views: 535
Re: When to round for sig figs?
Wait to round until the end of the problem to usually 3 sig figs. Also if the ending decimal is continuous, underline the number of three sigs figs in the problem.
- Fri Oct 04, 2019 10:21 am
- Forum: Balancing Chemical Reactions
- Topic: Homework Question H.5 (c)
- Replies: 2
- Views: 177
Homework Question H.5 (c)
Can someone help me balance this chemical equation:
NaCl(aq) + SO3(g) + H2O(l) -------> Na2SO4(aq) + HCl(aq)
I tried multiple approaches, but I can never get the oxygen to equal out.
Thank you.
NaCl(aq) + SO3(g) + H2O(l) -------> Na2SO4(aq) + HCl(aq)
I tried multiple approaches, but I can never get the oxygen to equal out.
Thank you.
- Tue Oct 01, 2019 11:28 pm
- Forum: Molarity, Solutions, Dilutions
- Topic: Post- Assessment Problem 16
- Replies: 2
- Views: 174
Post- Assessment Problem 16
How would I solve this problem, I'm not really sure where to start or how to implement the equation. 16. A solution is prepared by dissolving 55.1 g of KCl in approximately 75 mL of water and then adding water to a final volume of 125 mL. What is the molarity of KCl(aq) in this solution? A. 0.276 mo...