Search found 92 matches

by Amy Kumar 1I
Sun Feb 16, 2020 8:01 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: endo/exo and temp
Replies: 8
Views: 26

Re: endo/exo and temp

In endothermic reactions, heat is like a reactant. This means that if heat is added, there are more reactants, which means that reaction will shift towards the products in the forward direction.
by Amy Kumar 1I
Sun Feb 16, 2020 7:56 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: Different Types of Entropies
Replies: 4
Views: 23

Re: Different Types of Entropies

The entropy of the system and surroundings added up equal the entropy of the surroundings. In cases where the entropy of the surroundings is 0, the entropy of the system equals -1*entropy of the surroundings.
by Amy Kumar 1I
Sun Feb 16, 2020 7:54 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Bond Enthalpies with Molecules
Replies: 4
Views: 26

Re: Bond Enthalpies with Molecules

Use the given positive values for all the bond enthalpies and use the equation (bonds broken)-(bonds formed) to calculate the overall delta h.
by Amy Kumar 1I
Sun Feb 16, 2020 5:31 pm
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: R constants
Replies: 20
Views: 311

Re: R constants

Make sure your units cancel out and the unit for pressure (bar, atm, Torr) matches the unit for the pressure value in the question.
by Amy Kumar 1I
Sun Feb 16, 2020 5:27 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs Irreversible
Replies: 8
Views: 28

Re: Reversible vs Irreversible

Reversible: w=-nRT(ln(v2/v1))
Irreversible: w=-p(delta v)
by Amy Kumar 1I
Mon Feb 10, 2020 3:12 am
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Internal Energy
Replies: 4
Views: 125

Re: Internal Energy

I was just on this problem and luckily found this post. Are we supposed to know that 1atm is equivalent to 760 torr or is that somewhere on the equation sheet? Also how do we convert from L*atm to kJ? Both conversions are given on the constants and equations sheet. 1 L.atm = 101.325 J 1 atm = 760 t...
by Amy Kumar 1I
Mon Feb 10, 2020 3:10 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Strong Acids
Replies: 6
Views: 18

Re: Strong Acids

Since strong acids dissociate completely, a Ka value is usually not given.
by Amy Kumar 1I
Mon Feb 10, 2020 3:02 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: delta U = 0
Replies: 2
Views: 10

delta U = 0

What are the different situations in which delta U can equal 0?
by Amy Kumar 1I
Mon Feb 10, 2020 3:00 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: delta h rxn at different temperatures
Replies: 1
Views: 10

delta h rxn at different temperatures

What is the setup for when the delta h rxn is given at a specific temperature but we are being asked to calculate the delta h rxn at another temperature?
by Amy Kumar 1I
Mon Feb 10, 2020 2:54 am
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: delta s = q(rev)/T
Replies: 1
Views: 9

delta s = q(rev)/T

Since the q value in the delta s = q(rev)/T equation is the energy transferred reversibly as heat, is there a separate equation needed to find q for a reversible reaction (similar to how there is a different equation to find w if the reaction is reversible)?
by Amy Kumar 1I
Mon Feb 10, 2020 2:52 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: when to change sign of enthalpies
Replies: 7
Views: 29

Re: when to change sign of enthalpies

Yes, taking the reverse reaction allows the products and reactants to switch sides so that things can get canceled out as needed.
by Amy Kumar 1I
Mon Feb 10, 2020 2:50 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: q=CΔT
Replies: 5
Views: 23

Re: q=CΔT

The heat capacity for the calorimeter takes the mass and everything else into account already.
by Amy Kumar 1I
Sun Feb 02, 2020 9:08 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Changing the energy of a system
Replies: 9
Views: 20

Changing the energy of a system

What are the three ways to change the energy of a system?
by Amy Kumar 1I
Sun Feb 02, 2020 9:06 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Reaction constant P
Replies: 3
Views: 15

Reaction constant P

Why is P*delta V significant for changes in the number of moles of gas and insignificant for solids and liquids?
by Amy Kumar 1I
Sun Feb 02, 2020 9:00 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: Boltzmann Equation [ENDORSED]
Replies: 1
Views: 275

Boltzmann Equation [ENDORSED]

What is the difference between the "small" and "large" errors in s and how does that influence whether a property is thermodynamic or statistical?
by Amy Kumar 1I
Sun Feb 02, 2020 8:58 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: negative delta U value
Replies: 2
Views: 14

negative delta U value

Why do we not know if a reaction will occur just because the delta U value is negative?
by Amy Kumar 1I
Sun Feb 02, 2020 8:48 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 4
Views: 13

Re: Hess's Law

Also make sure to check if the the reactants and products are on their appropriate sides across all the equations before making changes to the equations.
by Amy Kumar 1I
Sun Jan 26, 2020 12:44 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Exceptions to Hess's Law
Replies: 1
Views: 10

Exceptions to Hess's Law

Are there any situations where you would not be able to simply "add" chemical reactions together to determine overall delta h?
by Amy Kumar 1I
Sun Jan 26, 2020 12:29 pm
Forum: Phase Changes & Related Calculations
Topic: Heat vs temperature
Replies: 6
Views: 37

Heat vs temperature

During lecture, there was a slide that mentioned that because heat is required during melting or boiling, the temperature of a sample remains constant even though heat is being added. Can someone please explain what this means?
by Amy Kumar 1I
Sun Jan 26, 2020 12:21 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Br2(l) --> 2Br(g)
Replies: 2
Views: 8

Br2(l) --> 2Br(g)

For the reaction Br2(l) --> 2Br(g), how do you know which phase change enthalpies to use (why is it delta h vap + delta h bond)?
by Amy Kumar 1I
Sun Jan 26, 2020 11:47 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: bond enthalpies
Replies: 2
Views: 9

Re: bond enthalpies

In the example that Dr. Lavelle used during lecture, drawing the Lewis structures reveals that the double bond between the carbons in ch2 is broken since the product (ch3ch2br) only has a single bond between the carbons. You would have to compare the Lewis structures of the reactants and the product...
by Amy Kumar 1I
Sun Jan 26, 2020 11:44 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: state functions
Replies: 4
Views: 10

Re: state functions

When is it a state function, you only need to take the initial and final states into consideration instead of all the intermediate pathways as well. This makes it easier to calculate change.
by Amy Kumar 1I
Mon Jan 20, 2020 2:13 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Solids and Liquids in K
Replies: 3
Views: 6

Re: Solids and Liquids in K

Liquids (solvents) are usually in excess in the reaction, so they are not included because there is no significant change in their concentrations.
by Amy Kumar 1I
Mon Jan 20, 2020 2:00 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: K value at a specific temp
Replies: 6
Views: 30

Re: K value at a specific temp

The basic idea is that K values change based on the temperature.
by Amy Kumar 1I
Mon Jan 20, 2020 1:56 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Endothermic Reactions
Replies: 4
Views: 12

Endothermic Reactions

Why does adding heat to a reaction drive product formation?
by Amy Kumar 1I
Mon Jan 20, 2020 1:51 pm
Forum: Ideal Gases
Topic: R constant for PV=nRT
Replies: 7
Views: 30

Re: R constant for PV=nRT

The R values are constant and change based on the units of pressure being used.
by Amy Kumar 1I
Mon Jan 20, 2020 1:49 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: X approx check
Replies: 2
Views: 9

Re: X approx check

Since values smaller than 10^-3 can typically allow the approximation method to be used, if the value is less than but somewhat close to 10^-3, you should definitely check to be sure.
by Amy Kumar 1I
Sun Jan 12, 2020 7:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units and Conversions of Kp
Replies: 3
Views: 19

Re: Units and Conversions of Kp

Just make sure the units are the same throughout, which means that the R value with the same unit is used in the equation.
by Amy Kumar 1I
Sun Jan 12, 2020 7:41 pm
Forum: Ideal Gases
Topic: PV = nRT Confusion
Replies: 4
Views: 31

Re: PV = nRT Confusion

By rearranging the ideal gas equation, n/v can be isolated for which means that the concentration can be calculated for because n/v is the concentration/molarity.
by Amy Kumar 1I
Sun Jan 12, 2020 7:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Thinking point 5J
Replies: 4
Views: 21

Re: Thinking point 5J

Since solids technically do not have a concentration, they are not involved in equilibrium constant equations. This means that equilibrium constants are the same even if the solid is removed.
by Amy Kumar 1I
Sun Jan 12, 2020 7:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: stoichiometric coefficients
Replies: 5
Views: 27

Re: stoichiometric coefficients

Stoichiometric coefficients are the exponents that show that there multiples quantities of the substance. In this case, the concentration values are raised to the power of the stoichiometric coefficients.
by Amy Kumar 1I
Sun Jan 12, 2020 7:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Difference between Kc/Kp and Q
Replies: 2
Views: 17

Re: Difference between Kc/Kp and Q

Q is when the values used at the concentrations at a specific time, not the equilibrium values at concentration. Kc and Kp use the concentration values at equilibrium.
by Amy Kumar 1I
Sun Dec 08, 2019 10:20 am
Forum: Amphoteric Compounds
Topic: amphiprotic vs amphoteric
Replies: 1
Views: 23

amphiprotic vs amphoteric

why are amphiprotic always amphoteric but not the other way around?
by Amy Kumar 1I
Sun Dec 08, 2019 10:19 am
Forum: Amphoteric Compounds
Topic: examples
Replies: 2
Views: 38

examples

what are the reactions for some amphoteric compounds showing that they can act as acids and bases?
by Amy Kumar 1I
Sun Dec 08, 2019 9:41 am
Forum: Hybridization
Topic: lone pairs in hybridization
Replies: 6
Views: 42

lone pairs in hybridization

how are lone pair shown in hybridization?
by Amy Kumar 1I
Sun Dec 08, 2019 9:41 am
Forum: Hybridization
Topic: pi bonds
Replies: 3
Views: 42

pi bonds

why are pi bonds shown in the p orbital?
by Amy Kumar 1I
Sun Dec 08, 2019 9:37 am
Forum: Dipole Moments
Topic: Cancelling dipole moments
Replies: 9
Views: 76

Re: Cancelling dipole moments

If the shape is tetrahedral and all attachments are the same, dipoles cancel.
by Amy Kumar 1I
Sun Dec 01, 2019 9:22 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: NO2-
Replies: 1
Views: 21

NO2-

Is nitro a mono, bi, or polydentate? Which element's lone pairs are considered?
by Amy Kumar 1I
Sun Dec 01, 2019 9:15 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 2
Views: 29

Polydentate

How do you determine if a ligand is polydentate?
by Amy Kumar 1I
Sun Dec 01, 2019 4:36 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Inductive Effect
Replies: 1
Views: 13

Inductive Effect

Can someone please explain the inductive effect in relation to delocalization.
by Amy Kumar 1I
Sun Dec 01, 2019 4:25 pm
Forum: Properties & Structures of Inorganic & Organic Bases
Topic: Metal Oxide and Water
Replies: 1
Views: 20

Metal Oxide and Water

What happens when a metal oxide reacts with water? Is a base produced or does the metal oxide break down into a metal cation and hydroxide ions?
by Amy Kumar 1I
Sun Dec 01, 2019 4:17 pm
Forum: Naming
Topic: Order of ligands in formulas for coordination compounds
Replies: 4
Views: 26

Re: Order of ligands in formulas for coordination compounds

Also, the anion is written before the neutral ligand.
by Amy Kumar 1I
Sun Dec 01, 2019 2:17 pm
Forum: Hybridization
Topic: Hybrid Orbitals
Replies: 4
Views: 35

Re: Hybrid Orbitals

The extra orbital is needed for the 4th electron in an sp2 orbital, which can hold 3 electrons. The un-hybridized p electron is unpaired.
by Amy Kumar 1I
Sun Dec 01, 2019 2:10 pm
Forum: Naming
Topic: How to Find the Roman Numeral
Replies: 4
Views: 27

Re: How to Find the Roman Numeral

Work backwards from the overall charge and charge of the ligands to find the charge on the metal.
by Amy Kumar 1I
Sun Nov 24, 2019 10:16 pm
Forum: Biological Examples
Topic: Porphyrin ligand-tetradentate
Replies: 2
Views: 77

Porphyrin ligand-tetradentate

Can someone please example the porphyrin ligand-tetradentate example from lecture with relation to heme complexes?
by Amy Kumar 1I
Sun Nov 24, 2019 10:14 pm
Forum: Biological Examples
Topic: Transition Metals and Oxidation States
Replies: 1
Views: 24

Transition Metals and Oxidation States

What is the biological benefit of transition metals having many oxidation states?
by Amy Kumar 1I
Sun Nov 24, 2019 10:13 pm
Forum: Naming
Topic: Di-, Tri-, Tetra- vs Bis-, Tris-, Tetrakis-
Replies: 11
Views: 57

Di-, Tri-, Tetra- vs Bis-, Tris-, Tetrakis-

When are bis-, tris-, tetrakis- used instead of di-, tri-, tetra-?
by Amy Kumar 1I
Sun Nov 24, 2019 10:11 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Sphere
Replies: 1
Views: 16

Coordination Sphere

Why are bound ligands a part of the coordination sphere?
by Amy Kumar 1I
Sun Nov 24, 2019 10:05 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: bronsted acid
Replies: 5
Views: 20

Re: bronsted acid

A bronsted acid is a chemical species that can donate a proton. An example is CH3COOH (acetic acid).
by Amy Kumar 1I
Sun Nov 24, 2019 10:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Hybridization
Replies: 7
Views: 34

Re: Hybridization

Hybridization makes it easier to see the different types of bonds that are present. It is also meant to show that the "fusing" of orbitals affects shapes and ability to bond.
by Amy Kumar 1I
Sun Nov 17, 2019 11:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Repulsion strength
Replies: 5
Views: 26

Re: Repulsion strength

Closer because radius is a variable in Coulomb's Law.
by Amy Kumar 1I
Sun Nov 17, 2019 11:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Axial and Equatorial Lone Pairs
Replies: 1
Views: 35

Axial and Equatorial Lone Pairs

How do we determine the different effects of axial and equatorial lone pairs on molecule shape?
by Amy Kumar 1I
Sun Nov 17, 2019 11:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Resonance and VSEPR
Replies: 9
Views: 40

Resonance and VSEPR

Are resonance structures considered when determining molecular shape?
by Amy Kumar 1I
Sun Nov 17, 2019 11:27 pm
Forum: Dipole Moments
Topic: Hydrogen Bonds and Polarity
Replies: 1
Views: 20

Hydrogen Bonds and Polarity

Is there formation of hydrogen bonds related in any way to polarity?
by Amy Kumar 1I
Sun Nov 17, 2019 11:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Radicals and molecular shape
Replies: 5
Views: 41

Re: Radicals and molecular shape

Radicals count as 1 region of electron density but the repulsion is not as great as that of a lone pair.
by Amy Kumar 1I
Sun Nov 17, 2019 11:22 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Trans vs Cis molecules
Replies: 2
Views: 22

Re: Trans vs Cis molecules

The cis molecule in the example during lecture was polar while the trans molecule was non-polar because the dipole moments canceled out.
by Amy Kumar 1I
Sun Nov 10, 2019 5:54 pm
Forum: Ionic & Covalent Bonds
Topic: Ionization of Nitrogen vs Oxygen
Replies: 11
Views: 61

Re: Ionization of Nitrogen vs Oxygen

The half-filled orbitals for nitrogen and more stable and harder to remove an electron from than the 1 orbital in oxygen that has 2 paired electrons.
by Amy Kumar 1I
Sun Nov 10, 2019 5:28 pm
Forum: Electronegativity
Topic: Differences in Electronegativity
Replies: 5
Views: 26

Re: Differences in Electronegativity

You can use the general trends in increasing and decreasing electronegative for the periodic table can help identify the general differences in electronegativity between 2 elements without needing to know the exact values.
by Amy Kumar 1I
Sun Nov 10, 2019 5:18 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Energy Levels
Replies: 4
Views: 48

Re: Energy Levels

By using (-hR/n^2) for the final n value minus (-hr/n^2) for the initial n value, you can find the energy difference. If the energy difference and one of the n values are known, you can rearrange the equation to find the other n value since -hR is a constant value.
by Amy Kumar 1I
Sun Nov 10, 2019 4:56 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical formula
Replies: 2
Views: 40

Re: Empirical formula

If you are given the mass of the reactants, convert it to moles of each reactant using the molar mass from the periodic table. Then divide each molar value by the smallest molar value and multiply to get whole numbers if necessary.
by Amy Kumar 1I
Sun Nov 10, 2019 4:54 pm
Forum: Resonance Structures
Topic: Resonance Structures
Replies: 3
Views: 26

Re: Resonance Structures

For boron, not having an octet and having just 6 shared electrons makes it formal charge 0 since it has 6 valence electrons. This is favorable for boron rather than having a complete octet.
by Amy Kumar 1I
Sun Nov 10, 2019 4:51 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Using the equation
Replies: 2
Views: 38

Re: Using the equation

You use the equation to find uncertainty in position or velocity, depending on what is given. If, for example, the velocity is given as 10 +/- 2 m/s, delta(velocity) would be 4 m/s and the question may ask you to find the difference in position (delta(position)) while the mass remains constant.
by Amy Kumar 1I
Sun Nov 03, 2019 6:36 pm
Forum: Lewis Structures
Topic: Single bond
Replies: 2
Views: 15

Re: Single bond

Yes. A bond represents 2 electrons being shared.
by Amy Kumar 1I
Sun Nov 03, 2019 5:50 pm
Forum: Lewis Structures
Topic: 2B.19
Replies: 1
Views: 16

Re: 2B.19

Triple bonds allow the octet to be satisfied for each element.
by Amy Kumar 1I
Sun Nov 03, 2019 5:49 pm
Forum: Molarity, Solutions, Dilutions
Topic: Dilution Equation
Replies: 4
Views: 52

Re: Dilution Equation

Make sure you keep your units constant though. In this case, your answer would be in mL too.
by Amy Kumar 1I
Sun Nov 03, 2019 3:21 pm
Forum: Lewis Structures
Topic: Lewis structure
Replies: 3
Views: 29

Re: Lewis structure

You should try to get the central atom to have a formal charge of 0, and if it is allowed to have an expanded octet, it can have more than 8 electrons.
by Amy Kumar 1I
Sun Nov 03, 2019 3:14 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 1B.26
Replies: 4
Views: 54

1B.26

A bowling ball of mass 8.00 kg is rolled down a bowling alley lane at 5.00 +/-5.0 m/s. What is the minimum uncertainty in its position?

Is the delta velocity 5.0 m/s or 10 m/s because it says +/- 5.0 m/s?
by Amy Kumar 1I
Sun Nov 03, 2019 3:11 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 1E.13
Replies: 2
Views: 18

Re: 1E.13

For silver, I would suggest writing the expected electron configuration and then switching the electron from the 5s to the 4d (since you're trying to get 4d^10). For beryllium, just go through the 1s, 2s order.
by Amy Kumar 1I
Sun Oct 27, 2019 3:17 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 5
Views: 32

Re: Formal Charge

Formal charge indicates the gain or loss of electrons that occurs when a covalent bond is formed since the electrons are shared in a covalent bond.
by Amy Kumar 1I
Sun Oct 27, 2019 3:16 pm
Forum: Lewis Structures
Topic: Lewis Structure of Ions
Replies: 6
Views: 38

Re: Lewis Structure of Ions

Yes, the brackets are placed around the entire structure with the charge in the corner to show the whole molecule's charge.
by Amy Kumar 1I
Sun Oct 27, 2019 3:08 pm
Forum: Lewis Structures
Topic: Drawing the structure
Replies: 7
Views: 48

Re: Drawing the structure

That shape is the resonance hybrid and it depicts the bond length as relatively equal rather than some being stronger than others. For example, the c-c single bond in benzene has a length of 1.54 Angstroms while the c=c double bond in benzene has a length of 1.34 Angstroms. Experimentally, however, ...
by Amy Kumar 1I
Sun Oct 27, 2019 2:48 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Central atom
Replies: 8
Views: 83

Re: Central atom

The formal charge of the central atom might not always be 0, but as long as the the sum of all the formal charges add up to the charge of the overall molecule, it's fine.
by Amy Kumar 1I
Sun Oct 27, 2019 2:45 pm
Forum: Resonance Structures
Topic: Resonance
Replies: 8
Views: 42

Re: Resonance

The purpose is to show that there may different possible ways that the bonds can be formed while the overall charges remain the same.
by Amy Kumar 1I
Sun Oct 27, 2019 2:41 pm
Forum: Trends in The Periodic Table
Topic: Cations
Replies: 8
Views: 35

Re: Cations

Since there are fewer electrons but the same number of protons, the protons have a greater pull on the fewer number of electrons, therefore those electrons are drawn in closer to the nucleus, making the size of the cation smaller.
by Amy Kumar 1I
Sat Oct 19, 2019 2:09 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Magnetic Quantum Number (ml)
Replies: 2
Views: 20

Magnetic Quantum Number (ml)

How do we know if the magnetic quantum number for orientation for the p orbital is -1,0,1 in relation to px, py, and pz?
by Amy Kumar 1I
Sat Oct 19, 2019 2:06 pm
Forum: Quantum Numbers and The H-Atom
Topic: spin state (ms) quantum number
Replies: 2
Views: 34

spin state (ms) quantum number

Is there any way to know whether the electrons ms quantum number of -1/2 or +1/2?
by Amy Kumar 1I
Sat Oct 19, 2019 2:03 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Hund's rule
Replies: 5
Views: 32

Re: Hund's rule

The parallel spins are from electrons occupying empty orbitals first. After that, they start to pair up, which leads to opposite spins.
by Amy Kumar 1I
Sat Oct 19, 2019 2:01 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Paired vs Parallel electrons
Replies: 5
Views: 21

Re: Paired vs Parallel electrons

Electrons occupy orbital individually first so the spins are parallel. Once the available orbitals have been filled, they start pairing up, which is where the opposite spins come from.
by Amy Kumar 1I
Sat Oct 19, 2019 1:59 pm
Forum: Properties of Light
Topic: Baler v. Lyman Series
Replies: 10
Views: 66

Re: Baler v. Lyman Series

The n=1 and n=2 states represent the energy level to which the electrons drop back to, which is what the Lyman and Balmer series represent.
by Amy Kumar 1I
Sun Oct 13, 2019 9:22 pm
Forum: Photoelectric Effect
Topic: Waves
Replies: 4
Views: 32

Re: Waves

Wavelength and frequency are inversely proportional, but amplitude is independent of both.
by Amy Kumar 1I
Sun Oct 13, 2019 9:18 pm
Forum: Limiting Reactant Calculations
Topic: How to find Excess Reactant?
Replies: 5
Views: 54

Re: How to find Excess Reactant?

Use the limiting reactant and molar ratio to find the amount of product formed. Subtract that from the amount of product would've been formed from the excess reactant.
by Amy Kumar 1I
Sun Oct 13, 2019 9:12 pm
Forum: Properties of Light
Topic: Relationship b/w wavelength and E
Replies: 5
Views: 39

Re: Relationship b/w wavelength and E

Higher wavelengths mean lower frequencies, which means that energy is lower. Therefore, energy is indirectly proportional to wavelength.
by Amy Kumar 1I
Sun Oct 13, 2019 4:21 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: atomic spectra
Replies: 5
Views: 61

Re: atomic spectra

A specific wavelength and frequency is associated with the photon that is released when the electrons drops back down to its original energy level. The equation e=hv can be used to determine the energy based on the frequency and plank's constant.
by Amy Kumar 1I
Sun Oct 13, 2019 4:17 pm
Forum: Properties of Light
Topic: SI units and wavelength
Replies: 6
Views: 26

Re: SI units and wavelength

Be careful if the question is asking/giving you the data in meters or nanometers because it can be used with both.
by Amy Kumar 1I
Sun Oct 13, 2019 4:15 pm
Forum: Limiting Reactant Calculations
Topic: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]
Replies: 68
Views: 1647

Re: Showing Work for Limiting Reactant Calculations on Tests [ENDORSED]

I made sure to use dimensional analysis to make it clear when units canceled out.
by Amy Kumar 1I
Fri Oct 04, 2019 12:39 pm
Forum: Limiting Reactant Calculations
Topic: General Limiting Reactant Question
Replies: 4
Views: 32

Re: General Limiting Reactant Question

If the mass of just one of the reactants is given, convert it to moles and use the molar ratio to find the amount of product. Don't worry about limiting reactant in that case.
by Amy Kumar 1I
Fri Oct 04, 2019 2:04 am
Forum: SI Units, Unit Conversions
Topic: Bond Length
Replies: 5
Views: 63

Re: Bond Length

Last lecture, we went over the unit angstrom (10^-10 m) which is often used with bond length.
by Amy Kumar 1I
Fri Oct 04, 2019 2:00 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: mol-1?
Replies: 5
Views: 79

Re: mol-1?

Sometimes writing grams and moles as division (g/mol) rather than g.mol^-1 may be helpful in a stoichiometric set up so that it's easy to visualize which units "cancel out"
by Amy Kumar 1I
Fri Oct 04, 2019 1:51 am
Forum: Empirical & Molecular Formulas
Topic: When to know to multiply by a whole number when finding the empirical formula
Replies: 5
Views: 47

Re: When to know to multiply by a whole number when finding the empirical formula

Some of the common decimals are .25, .33, and .5 so in those cases, there is a clear way to multiply and make the quantity a whole number. Try to find a number you can multiply it too to get as close to a whole number as possible.
by Amy Kumar 1I
Thu Oct 03, 2019 7:31 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reagent Ratios
Replies: 4
Views: 56

Re: Limiting Reagent Ratios

You can either do it in the way of comparing how many moles of a certain amount of a reactant is needed in comparison to the molar quantity of the second reactant or you can compare how many moles of product would be formed from the two reactant molar quantities independently. In both cases, molar r...
by Amy Kumar 1I
Thu Oct 03, 2019 7:21 pm
Forum: Balancing Chemical Reactions
Topic: Understanding how to get whole #s [ENDORSED]
Replies: 18
Views: 157

Re: Understanding how to get whole #s [ENDORSED]

For empirical formulas, if the value you got after dividing by the smallest number of moles was a decimal such as .25, .33, or .5, you would need to multiply all the molar quantities by the same number to make the decimal value a whole number.
by Amy Kumar 1I
Thu Oct 03, 2019 10:16 am
Forum: Molarity, Solutions, Dilutions
Topic: E 29 part c
Replies: 8
Views: 998

Re: E 29 part c

For part d, you must figure out the mass of oxygen as part of the formula. Since there is 4 oxygen atoms, the mass of oxygen is 16x4=64. By dividing that by the total mass of the formula, 206.446, you can figure out what fraction of the total mass was due to oxygen. 64/206.446=.310008 or 31%. Do yo...

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