Search found 100 matches

by MinuChoi
Sat Mar 14, 2020 6:50 pm
Forum: First Order Reactions
Topic: Half Life
Replies: 1
Views: 52

Re: Half Life

I think it has to do with the fact that a first-order reaction's rate scales directly with the concentration (rate = k[A]). If you increase the concentration of the reactant, the rate will also increase by the same scalar. The half life isn't affected by this change because while there would be more...
by MinuChoi
Sat Mar 14, 2020 6:44 pm
Forum: Van't Hoff Equation
Topic: ln
Replies: 9
Views: 103

Re: ln

eln(x) = x
by MinuChoi
Sat Mar 14, 2020 6:32 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal Energy
Replies: 6
Views: 94

Re: Internal Energy

The internal energy of an ideal gas is proportional to its mass and temperature (deltaU = 1.5*n*R*deltaT). Both mass and temperature are constant in an isothermal expansion, so the internal energy is constant (deltaU = 0). Internal energy, heat, and work are related by deltaU = q + w. deltaU = 0, so...
by MinuChoi
Sat Mar 14, 2020 6:23 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Non spontaneous to spontaneous process?
Replies: 2
Views: 57

Re: Non spontaneous to spontaneous process?

Given the above statements are true: deltaG = deltaH - T*deltaS. If deltaS > 0, then T*deltaS is positive. Increasing T means that T*deltaS becomes larger, but it is subtracted. So deltaG would be decreasing as T increases. If your deltaG is positive before you start increasing temperature, then the...
by MinuChoi
Sat Mar 14, 2020 6:12 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: A- frequency factor
Replies: 3
Views: 47

Re: A- frequency factor

A's numerical value is unique for a reaction just like the rate constant k. It also has the same units as the rate constant. A unique first-order reaction has a unique rate constant k and frequency factor A, both with units s -1 (because it is a first-order reaction). k and A are related by the Arrh...
by MinuChoi
Sun Mar 08, 2020 3:48 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: A in the Arrhenius Equation
Replies: 8
Views: 70

Re: A in the Arrhenius Equation

Note that the A constant is a unique value for each chemical reaction, like the k constant.
by MinuChoi
Sun Mar 08, 2020 3:44 pm
Forum: Second Order Reactions
Topic: Half-life of Second-Order
Replies: 4
Views: 299

Re: Half-life of Second-Order

Also need to know: for a zero-order reaction, t1/2=[A0]/2k
by MinuChoi
Sun Mar 08, 2020 3:38 pm
Forum: Zero Order Reactions
Topic: Not used Half life
Replies: 8
Views: 366

Re: Not used Half life

The half-life of a second-order reaction is t1/2=1/k[A0]
by MinuChoi
Sun Mar 08, 2020 3:36 pm
Forum: Kinetics vs. Thermodynamics Controlling a Reaction
Topic: units
Replies: 11
Views: 88

Re: units

Adding on, keep in mind that these units are the same for all rates regardless of order; because of this, the k constant of the reaction will have different units based on the reaction's order.
by MinuChoi
Sun Mar 08, 2020 3:34 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: What is 'A'?
Replies: 5
Views: 65

Re: What is 'A'?

A is a unique constant for a chemical reaction, similar to the k constant of a reaction.
by MinuChoi
Sun Mar 01, 2020 2:50 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Salt Bridge
Replies: 10
Views: 45

Re: Salt Bridge

I noticed that some cell diagrams in the homework don't include salt bridges.. when is this possible? If you look at figures 6L2 and 6L3 in the textbook, there are cells in which the two half-reaction solutions have some contact with each other; so some cells have other means of ion transfer than a...
by MinuChoi
Sun Mar 01, 2020 2:23 pm
Forum: First Order Reactions
Topic: first order
Replies: 4
Views: 63

Re: first order

For a first-order reaction, the rate is directly proportional to the concentration (e.g. if the concentration of a reactant was doubled, the rate of the reaction would be doubled.) For a second-order reaction, the rate is proportional to the second power (square) of the concentration (e.g. if the co...
by MinuChoi
Sun Mar 01, 2020 2:18 pm
Forum: General Rate Laws
Topic: units
Replies: 9
Views: 75

Re: units

Units are change in concentration per second (mol x L-1 x s-1). Keep in mind that because of this, the reaction constant k may have different units for different rate laws.
by MinuChoi
Sun Mar 01, 2020 2:13 pm
Forum: General Rate Laws
Topic: Integrated Rate Law
Replies: 5
Views: 54

Re: Integrated Rate Law

Integrated rate laws show reaction rate vs. time. Differential rate laws show rate as a function of the reactant concentration [R].
by MinuChoi
Sun Mar 01, 2020 2:10 pm
Forum: Balancing Redox Reactions
Topic: 6K3 Help
Replies: 1
Views: 39

Re: 6K3 Help

Note that there are two sulfur atoms involved. The oxidation number of each sulfur in the reactants is +2. In the products. each is +6. Each sulfur has an oxidation number increase of +4, so there is a net transfer of eight electrons as shown in the balanced oxidation reaction.
by MinuChoi
Sun Feb 23, 2020 2:54 pm
Forum: Balancing Redox Reactions
Topic: Alkaline reactions
Replies: 2
Views: 24

Re: Alkaline reactions

I believe the main difference is that at after you combine the half-reactions, you neutralize the H+ by adding hydroxide to each side of the equation.
by MinuChoi
Sun Feb 23, 2020 2:51 pm
Forum: Balancing Redox Reactions
Topic: Figuring Out Electrons Transferred for a Problem Where Both Sides Have The Same Oxidation Number
Replies: 3
Views: 36

Re: Figuring Out Electrons Transferred for a Problem Where Both Sides Have The Same Oxidation Number

I think if you balance the half reaction O3 -> O2, you'll get O3 + 2H+ + 2e- = O2 + H2O. Notice that this actually is a reduction reaction since the ozone gains electrons (reactant side). So This would work as a half-reaction even though the oxidation numbers don't change.
by MinuChoi
Sun Feb 23, 2020 2:39 pm
Forum: Balancing Redox Reactions
Topic: Balancing Redox reactions
Replies: 4
Views: 40

Re: Balancing Redox reactions

Adding on, keep in mind you add H2O to balance O regardless of acidic/basic reaction. It's the hydrogen/proton balancing that's different for acidic/basic.
by MinuChoi
Sun Feb 23, 2020 2:31 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: salt bridge
Replies: 5
Views: 27

Re: salt bridge

The ultimate purpose of the salt bridge is to keep the battery running (so it doesn't run itself to equilibrium quickly). It does so by maintaining charge balance as mentioned above.
by MinuChoi
Fri Feb 21, 2020 11:02 am
Forum: Balancing Redox Reactions
Topic: Oxidation numbers
Replies: 6
Views: 55

Re: Oxidation numbers

Keep in mind that any molecule made of only one element will have oxidation number of 0 if it's neutral charge.
by MinuChoi
Sun Feb 16, 2020 6:58 pm
Forum: Balancing Redox Reactions
Topic: Reduction vs. oxidation
Replies: 29
Views: 209

Re: Reduction vs. oxidation

In an equation, you can also look at oxidation numbers. Oxidized elements will have an increased oxidation number in the products. Reduced elements will have a decreased oxidation number.
by MinuChoi
Sun Feb 16, 2020 6:56 pm
Forum: Balancing Redox Reactions
Topic: Identifying Elements Undergoing Oxidation/Reduction
Replies: 5
Views: 30

Re: Identifying Elements Undergoing Oxidation/Reduction

Are you ignoring the H+ and H2O in the reactant and product? Do they not matter for this problem? They don't really matter for part a. To find the oxidation number of a single element in a compound, you don't really need to look at the other reactants. But you will definitely need to consider them ...
by MinuChoi
Sun Feb 16, 2020 6:50 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Gibb's Free Energy
Replies: 7
Views: 48

Re: Gibb's Free Energy

Gibb's Free Energy is energy available to do work in reaction. It's different from other energy functions (like enthalpy) because it takes energy loss due to entropy into account, since real work is not 100% reversible.
It's mainly used to tell If a reaction is spontaneous.
by MinuChoi
Sun Feb 16, 2020 6:44 pm
Forum: Balancing Redox Reactions
Topic: Identifying Elements Undergoing Oxidation/Reduction
Replies: 5
Views: 30

Re: Identifying Elements Undergoing Oxidation/Reduction

You can also look at the element's oxidation number before and after the equation. Elements whose oxidation number increases are oxidized, and vice versa for reduced. For 6K1: Given H is typically +1 oxidation and oxygen is typically -2 oxidation number, we can tell that our two elements undergoing ...
by MinuChoi
Sun Feb 16, 2020 6:29 pm
Forum: Balancing Redox Reactions
Topic: Oxygen
Replies: 9
Views: 51

Re: Oxygen

I believe that is correct for almost all compounds. There are some rare exceptions like peroxides and metal hydrides.
by MinuChoi
Sun Feb 09, 2020 4:00 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Intensive vs. extensive, state vs. non state
Replies: 6
Views: 62

Re: Intensive vs. extensive, state vs. non state

Not too sure about relation between intensive/extensive and state/nonstate, but state/non-state functions so far have usually in relation to equilibrium and energy processes (enthalpy, specific heat, and Gibbs free energy are all examples of state functions). Intensive/extensive properties are deter...
by MinuChoi
Sun Feb 09, 2020 3:54 pm
Forum: Phase Changes & Related Calculations
Topic: heat added/released
Replies: 6
Views: 55

Re: heat added/released

I think you could find this by determining of the reaction is exothermic or endothermic reactions (endothermic reactions require a heat input). Sometimes you can tell this just by looking at the reaction. Ex. If the rxn is one reactant being broken into several products, it's probably exothermic bec...
by MinuChoi
Sun Feb 09, 2020 3:51 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Higher the heat capacity
Replies: 4
Views: 31

Re: Higher the heat capacity

Adding on, this is a separate term from heat capacity, which is not measured per gram (The heat capacity of 5 grams of water is different than that of 10 grams of water).
by MinuChoi
Sun Feb 09, 2020 3:44 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: How is heat capacity a state function?
Replies: 3
Views: 1762

Re: How is heat capacity a state function?

I thought that if it relies on the change in heat/transfer of heat then it is not a state function? Heat capacity's reliance on heat transfer is consistent (how the heat is added does not change the temperature outcome), so it is a state function. Keep in mind that enthalpy is also a state function...
by MinuChoi
Sun Feb 09, 2020 3:38 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Calorimeter and Bomb Calorimeter
Replies: 4
Views: 34

Re: Calorimeter and Bomb Calorimeter

Adding on, because calorimeter's measure temperature changes, they will typically be seen in problems regarding specific heat capacities.
by MinuChoi
Sun Feb 02, 2020 12:48 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Phase change
Replies: 20
Views: 131

Re: Phase change

Enthalpy will be positive because the molecules must absorb energy to loosen forces on each other and assume more free form.
by MinuChoi
Sun Feb 02, 2020 12:46 pm
Forum: Calculating Work of Expansion
Topic: graphs of irreversible vs reversible?
Replies: 2
Views: 17

Re: graphs of irreversible vs reversible?

An irreversible expansion happens under a constant pressure, while the pressure for a reversible expansion will vary. So the pressure values will show differently on the graphs.
by MinuChoi
Sun Feb 02, 2020 12:39 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Combustion Reactions
Replies: 5
Views: 57

Re: Combustion Reactions

Does anyone have any good videos explaining combustion reactions?


There's a brief explanation in the textbook section F63.
by MinuChoi
Sun Feb 02, 2020 12:30 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Extensive/Intensive Property
Replies: 4
Views: 33

Re: Extensive/Intensive Property

what is the difference between extensive and intensive properties? just that they are affected by volumes?

Extensive properties change based on the amount present. Intensive properties do not.
by MinuChoi
Sun Feb 02, 2020 12:26 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
Replies: 1
Views: 26

Re: Boltzmann Equation

This equation is used to calculate the entropy of an object when we know how many ways the molecules in the system can be arranged without changes in energy. If we know that a molecule can be oriented in X number of ways , we can find the entropy of virtually any amount of that compound using the re...
by MinuChoi
Sun Jan 26, 2020 4:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: protonization/ionization
Replies: 4
Views: 51

Re: protonization/ionization

If you look at an ICE chart of the reaction, this would be the concentration of the conjugate product at equilibrium over the initial concentration of the acid/base.
by MinuChoi
Sun Jan 26, 2020 4:34 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity
Replies: 7
Views: 71

Re: Heat Capacity

How do we know the heat capacity?


There's a formula for calculating it given heat and temperature (textbook p. 251). For specific heat capacities, those are unique for every substance.
by MinuChoi
Sun Jan 26, 2020 4:27 pm
Forum: Phase Changes & Related Calculations
Topic: State Properties
Replies: 4
Views: 34

Re: State Properties

A state property is determined only by the "start" and "finish" values of a process. Basic example: If I walk 5m forward, then walk backward 2m, I am 3m forward from my original staring point. This displacement would be the same if I simply walked 3m forward; or if I walked 500m ...
by MinuChoi
Sun Jan 26, 2020 9:49 am
Forum: Calculating Work of Expansion
Topic: Calculating Work
Replies: 1
Views: 16

Re: Calculating Work

Pay attention to what the work is in reference to. Say you have a system and surroundings. If positive work is done BY the system, energy in the system is expended. This is equivalent to NEGATIVE work done ON the system. If negative work is done BY the system, energy is put into the system. This is ...
by MinuChoi
Sun Jan 26, 2020 9:42 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat Capacity
Replies: 7
Views: 71

Re: Heat Capacity

Substances with higher heat capacity require more energy to raise its temperature and will have to expend more energy to cool down. If you're referring to heat transfer between two substances, the substance with a higher heat capacity will experience a smaller change in temperature because more ener...
by MinuChoi
Fri Jan 17, 2020 3:39 pm
Forum: Ideal Gases
Topic: ph
Replies: 10
Views: 100

Re: ph

when trying to find the pH or poH of something, do We take the - log of the opposite concentration of the one we are trying to find?

No; pH = -log[H+] and pOH=-log[OH-].
But you can use pH to find pOH and vice versa because pH + pOH = 14.
by MinuChoi
Fri Jan 17, 2020 3:36 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH
Replies: 2
Views: 65

Re: pH

pH is a scale. It's logarithmic, so a linear increase in pH is not a linear increase in [H+].
by MinuChoi
Fri Jan 17, 2020 3:33 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5 percent rule
Replies: 10
Views: 87

Re: 5 percent rule

The 5% rule should be considered when you remove x- additions/subtracts to make the ICE equation easier to solve (when K <10^-3)
by MinuChoi
Fri Jan 17, 2020 3:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Homework question 5H.1 PART B
Replies: 2
Views: 27

Re: Homework question 5H.1 PART B

The (b) equation is the original equation of the problem scaled by 1/2. If you multiple an entire equation by a scalar (in this case, 1/2), the K constant changes by being raised to that power (in this case, K=41 is raised to the power 1/2 to get K for the part b equation).
by MinuChoi
Fri Jan 17, 2020 3:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6B.11 Part b
Replies: 1
Views: 23

Re: 6B.11 Part b

Keep in mind that this problem is asking for mass, not concentration. So you don't need the MV formula because you already have the necessary concentration, but concentration x volume = mass. Concentration is independent of volume, so the 18 mol/L for the original 5mL solution applies also to the or...
by MinuChoi
Fri Jan 10, 2020 4:08 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Catalysts
Replies: 7
Views: 54

Re: Catalysts

A common example of catalyst is enzymes, proteins that facilitate reactions in biological systems. For example, amylase is an enzyme in saliva that breaks starches from food into digestible sugars at a faster rate. Without enzymes like amylase, it would be much slower gaining energy from consumed fo...
by MinuChoi
Fri Jan 10, 2020 3:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: reactants compared to products
Replies: 4
Views: 47

Re: reactants compared to products

Whether or not product equilibrium concentration will increase depends on the reaction's K constant. For example, if you start with a higher concentration of reactants and products and the reaction's K value is very high, yes, product will be formed and the product concentration will be increased at...
by MinuChoi
Fri Jan 10, 2020 3:52 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: N2+3H2<->2NH3
Replies: 5
Views: 46

Re: N2+3H2<->2NH3

When a reaction goes right, it will begin producing more net product. One case that this will happen in this example is when reactant is added (N2 is increased)
by MinuChoi
Fri Jan 10, 2020 3:46 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5I.23 Final Answer
Replies: 1
Views: 23

Re: 5I.23 Final Answer

Some of the intermediate calculations are rounded in the answer book. I don't think the difference is that significant, though.
by MinuChoi
Fri Jan 10, 2020 3:40 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: PCl5 example in lecture
Replies: 2
Views: 27

Re: PCl5 example in lecture

The 2X change is correct. Remember, the Xs represent how much product is produced when reactant is consumed, and this is based on the stoichiometric coefficients. The 2x^2 is probably referring to the K constant. From his example, we used the ICE chart's equilibrium values to determine constant K = ...
by MinuChoi
Sat Dec 07, 2019 4:21 pm
Forum: Sigma & Pi Bonds
Topic: Sigma Vs Pi
Replies: 10
Views: 190

Re: Sigma Vs Pi

Also know where the bonds form.
A single bond has one sigma bond.
Double bonds have one sigma and one pi bond.
Triple bonds have one sigma and two pi bonds.
by MinuChoi
Sat Dec 07, 2019 4:15 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Relationship between pKa, pKb, and acidity strength?
Replies: 1
Views: 25

Re: Relationship between pKa, pKb, and acidity strength?

pK = -logK. K is an equilibrium constant (Ka for acids, Kb for bases)
pKw = 14.
pKa + pKb = pKw
Stronger acids have a higher Ka value and a lower pKa value. Same goes for bases and Kb.
by MinuChoi
Sat Dec 07, 2019 3:54 pm
Forum: Significant Figures
Topic: Significant Figures during the Final.
Replies: 1
Views: 95

Re: Significant Figures during the Final.

You can just add zeros if you need more sig figs (say, 0.34 to 0.340). Also, as long as it isn't too small, you don't always have to bother with scientific notation (0.045 and 4.5x10^-2 would both likely be acceptable)
by MinuChoi
Sat Dec 07, 2019 3:49 pm
Forum: Hybridization
Topic: Hybradization
Replies: 3
Views: 99

Re: Hybradization

That first 2 refers to the shell n=2: The orbitals in the valence shell are being hybridized (because only the valence electrons are involved in bonding) and the valence shell for carbon is n=2.

I don't think it's 100% necessary (in the textbook it's not used all the time).
by MinuChoi
Sat Dec 07, 2019 3:43 pm
Forum: Amphoteric Compounds
Topic: Amphoteric vs. Amphoprotic
Replies: 1
Views: 63

Re: Amphoteric vs. Amphoprotic

Both terms refer to substances that behave as acids and bases, but amphiprotic substances have hydrogen atoms (they can donate protons). So amphiprotic substances also are amphoteric, but not always vice versa. ex. Aluminum oxide is amphoteric but not amphiprotic, because it can react to both acid a...
by MinuChoi
Sun Dec 01, 2019 9:11 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Number
Replies: 6
Views: 58

Re: Coordination Number

Coordination number is how many ligands are directly bonded to the central atom. This is basically everything in the coordination sphere, so coordination number = number of ligands in the bracket. For your example: in the bracket are 4 ligands (Br4) bound to the transition metal. The coordination nu...
by MinuChoi
Sun Dec 01, 2019 9:08 am
Forum: Biological Examples
Topic: Vitamin B12
Replies: 3
Views: 35

Re: Vitamin B12

B12 specifically acts as a coenzyme in the production of said components.
by MinuChoi
Sun Dec 01, 2019 8:54 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Oxidation number
Replies: 3
Views: 34

Re: Oxidation number

The sum of oxidation numbers of each component is the complex's overall charge. Anions have oxidation numbers equal to their charges. This includes anion ligands. Neutral ligands have oxidation number 0. Cations with fixed charges (like K[sup]+/sup]) have oxidation numbers equal to their charges. Fr...
by MinuChoi
Sun Dec 01, 2019 8:41 am
Forum: Biological Examples
Topic: Cisplatin vs Transplatin
Replies: 2
Views: 36

Re: Cisplatin vs Transplatin

The cis-chlorine arrangement on cisplatin (the two chlorines are on the same side of the central atom) is what allows it to bind as a ligand to DNA molecules. This interaction interrupts DNA replication, so it can be used to treat cancerous cells. Transplatin does not have this cis-chlorine arrangem...
by MinuChoi
Sun Dec 01, 2019 8:27 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Mondentate/Bidentate
Replies: 1
Views: 29

Re: Mondentate/Bidentate

I believe water is only monodentate because the available lone pairs are on one atom; even though there are two open lone pairs, the geometry would not favor two attractions to the same atom.
by MinuChoi
Sun Nov 24, 2019 8:40 pm
Forum: Naming
Topic: Oxidation Numbers
Replies: 2
Views: 45

Re: Oxidation Numbers

Oxidation numbers are a measure of the relative number of electrons each atom in a molecule has. I believe it's measured because of how some atoms share electrons in bonds. When all the atomic numbers of the atoms in a molecule are added up, they equal the molecules overall charge. But keep in mind ...
by MinuChoi
Sun Nov 24, 2019 8:33 pm
Forum: Naming
Topic: Meaning of Cis and Trans
Replies: 11
Views: 86

Re: Meaning of Cis and Trans

Adding on:
cis- means something like "on one side", and trans means "across".
cis-molecule are typically polar and trans-molecules are typically nonpolar.
by MinuChoi
Sat Nov 23, 2019 1:48 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination number
Replies: 1
Views: 34

Re: Coordination number

I don't think there is one. You could guess a possible shapes based on the coordination number, but its not reliable like VSEPR is (VSEPR doesn't apply to these complexes)
by MinuChoi
Sat Nov 23, 2019 1:39 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 4
Views: 33

Re: Polydentate

Note that polydentate can refer to tridentate, tetradentate, etc (not mono- or bidentates). It depends on how many atoms in the ligand have lone pairs available.
by MinuChoi
Sat Nov 23, 2019 1:26 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Sphere
Replies: 2
Views: 24

Re: Coordination Sphere

Adding on, note that because the sphere is the central atom and bonded ligands, not all components in a coordinate complex may be in the coordination sphere. That's why in the notation, the components in the coordinate sphere are bracketed.
by MinuChoi
Sun Nov 17, 2019 1:17 pm
Forum: Bond Lengths & Energies
Topic: Polarizability
Replies: 4
Views: 63

Re: Polarizability

Polarizability in anions is how easily the electron cloud of an atom is distorted. It's a greater value for larger anions. For cations, polarizability is low but polarizing power is high (how easily it can attract the electrons from another atom. This value is typically greater for smaller, more pos...
by MinuChoi
Sun Nov 17, 2019 1:08 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Repulsion Strength
Replies: 4
Views: 38

Re: Repulsion Strength

Repulsion between lone pairs > repulsion between a lone pair and a bonding pair> repulsion between bonding pairs
by MinuChoi
Sun Nov 17, 2019 1:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pair location
Replies: 3
Views: 48

Re: Lone Pair location

In some shapes such as bent, it is physically impossible to have lone pairs on opposite sides of the atom. Keep in mind the tetrahedral geometry of bent molecules. For the t-shape, you'll want to look at the lone pair's angles with the other 3 bonds. In the t-shape position, the lone pairs have high...
by MinuChoi
Sun Nov 17, 2019 12:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR
Replies: 6
Views: 48

Re: VSEPR

Adding on, minimal electrostatic repulsion is achieved when the electron-dense regions (bonds and lone pairs) on an atom are farthest from each other. There is an approximate maximum angle between bonds that can be achieved based on how many bonds are on that atom, and that is the basis of the bond ...
by MinuChoi
Thu Nov 14, 2019 2:25 pm
Forum: Bond Lengths & Energies
Topic: Dashes and Wedges
Replies: 4
Views: 33

Re: Dashes and Wedges

We won't be asked to actually draw the dashes/wedges diagrams.
by MinuChoi
Sat Nov 09, 2019 4:21 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: Hydrogen Bonding
Replies: 4
Views: 43

Re: Hydrogen Bonding

I think there is a possibility of other electronegative atoms forming hydrogen bonds, but N/O/F are the specific elements for which the hydrogen bonds are favorable and the strongest, so N/O/F hydrogen bonds are the only ones we should be concerned with.
by MinuChoi
Thu Nov 07, 2019 3:07 pm
Forum: Lewis Structures
Topic: When to draw Resonance Structures
Replies: 14
Views: 138

Re: When to draw Resonance Structures

How do we know when a molecule has resonance? After optimizing formal charges on the Lewis structure, you will typically find resonance if there is an arrangement of single/double bonds (maybe triple, though we haven't seen that in class yet) that can be moved around without affecting the overall d...
by MinuChoi
Thu Nov 07, 2019 2:50 pm
Forum: SI Units, Unit Conversions
Topic: Kj
Replies: 6
Views: 173

Re: Kj

Would you divide or multiply?


Multiply by 1000 when converting from kilojoules to souls.
Divide by 1000 for vice versa.
by MinuChoi
Wed Nov 06, 2019 2:00 pm
Forum: Lewis Structures
Topic: Ionic Lewis structure
Replies: 2
Views: 50

Re: Ionic Lewis structure

We're not being tested on nomenclature, so while it's probably good to know the basic ones (like ionic ones such as magnesium sulfide), there shouldn't be any questions that we can't do if we don't know nomenclature.
by MinuChoi
Wed Nov 06, 2019 1:46 pm
Forum: Properties of Light
Topic: Speed of Light
Replies: 7
Views: 200

Re: Speed of Light

c is given as 3.00 x 108 meters per second (m/s)
by MinuChoi
Thu Oct 31, 2019 3:08 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 4
Views: 45

Re: Formal Charge

What's the formal charge of NaOH?

NaOH is an ionic compound, so you would draw Na+ and OH- structures separately.
Looking at the structures and using the formal charge formula, you would get:
Na would have FC=1, H would have FC=0, and O would have FC=-1.
by MinuChoi
Thu Oct 31, 2019 3:00 pm
Forum: Lewis Structures
Topic: Valence Electrons from Periodic Table
Replies: 10
Views: 132

Re: Valence Electrons from Periodic Table

For example, hw problem 2A.1a asks to give the number of valence electrons (including d electrons) for the element Sb. Since it asked to include d-block, the answer would be 15 valence electrons not 5 electrons correct? The valence electrons for Sb would be 5. Keep in mind that the d-block (4d) tha...
by MinuChoi
Thu Oct 31, 2019 2:49 pm
Forum: Lewis Structures
Topic: Charges on Lewis Structures
Replies: 7
Views: 76

Re: Charges on Lewis Structures

For example is we had Br03- and we were adding up the electrons why would we add one instead of subtract one? A charge of -1 means that the compound has 1 extra electron (more electrons than protons means a negative charge). The Lewis structure would show an amount of electrons equal to the total o...
by MinuChoi
Thu Oct 31, 2019 2:39 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge equation
Replies: 9
Views: 74

Re: Formal Charge equation

Bond length probably won't work for that. But that form FC=V-(L+B) would work for B = number of bonds that atom has (+1 for singles, +2 for doubles), which is essentially the same thing as S/2. It's actually easier for me personally to do FC = V - (L+B) because I can simply count the number of bonds...
by MinuChoi
Thu Oct 31, 2019 2:09 pm
Forum: Lewis Structures
Topic: 2B.7
Replies: 2
Views: 37

Re: 2B.7

You can use valence electron values to identify E. Count how many electrons are in the Lewis structure. It looks like the structure has 32 electrons based on the four bonds described. You also know the structure has an atom of element E, one oxygen, and three chlorines. You can subtract those atoms'...
by MinuChoi
Thu Oct 24, 2019 4:11 pm
Forum: Trends in The Periodic Table
Topic: Location of elements
Replies: 12
Views: 175

Re: Location of elements

Does anyone know if we should know the elements' chemical symbols too? You'll be given a periodic table on the test, so memorizing all of the elements' symbols is likely not necessary. It's good to know most of the symbols for the more common atoms for efficiency, though. Maybe consciously make not...
by MinuChoi
Thu Oct 24, 2019 3:02 pm
Forum: Properties of Light
Topic: memorize radiation and its frequencys?
Replies: 2
Views: 47

Re: memorize radiation and its frequencys?

You should definitely know the order of types of radiation and an approximate range of frequencies/wavelengths for most of the radiations. I'm now sure if the specific frequencies need to be memorized, but you should probably at least be able to determine that, for example, 400-700nm light is in the...
by MinuChoi
Thu Oct 24, 2019 2:34 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: subshell or orbital?
Replies: 3
Views: 65

Re: subshell or orbital?

s, p, d, and f are subshells. One p-subshell has three orbitals.

3p is a subshell, but you can also specify a 3p-orbital.
by MinuChoi
Thu Oct 24, 2019 2:22 pm
Forum: Trends in The Periodic Table
Topic: Periodic Trend Exceptions
Replies: 7
Views: 74

Re: Periodic Trend Exceptions

can someone explain to me what trends are? The periodic trends are traits of atoms that change based on the element and can be visualized on the periodic table. For example: atomic radius (basically how big the atoms are). If you put every element's atomic radius on a periodic table, that value wil...
by MinuChoi
Thu Oct 24, 2019 2:14 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Energy of spdf orbitals
Replies: 11
Views: 130

Re: Energy of spdf orbitals

Can someone explain what a shell is vs a subshell? The shell is the n quantum number (broadest division of electrons in an atom). Shells correspond to the rows in the periodic table. The subshell is the s-p-d-f classification of orbital groups (quantum number l.) Shells are divided into subshells (...
by MinuChoi
Thu Oct 17, 2019 4:29 pm
Forum: Quantum Numbers and The H-Atom
Topic: (N,l,m)
Replies: 2
Views: 66

Re: (N,l,m)

The quantum number m l tells us which orbital an electron is in. For example, if an electron is in an orbital in the 2p subshell: we know that the 2p-subshell (l=1) has 3 orbitals. These orbitals within 2p are denoted as m l =-1,0,1, which is based on the quantum number l. An electron in a 2p subshe...
by MinuChoi
Thu Oct 17, 2019 4:23 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Planes
Replies: 7
Views: 106

Re: Nodal Planes

I recommend looking in the textbook pages 37-38 for a visual. You'll notice the nodal planes divide the lobes of the orbitals and that the nodal planes all cross the nucleus.
by MinuChoi
Thu Oct 17, 2019 4:12 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 1D.19
Replies: 2
Views: 19

Re: 1D.19

The manual just gives the orbitals. You may have been looking at a different solution.
by MinuChoi
Thu Oct 17, 2019 11:40 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Magnetic Quantum number [ENDORSED]
Replies: 4
Views: 86

Re: Magnetic Quantum number [ENDORSED]

In the 3p subshell, where l=1, does this mean ml=0? Can ml=0?


Yes. The possible magnetic quantum numbers ml for electrons with l=1 (p-orbitals) are -1, 0, 1.
by MinuChoi
Thu Oct 17, 2019 11:34 am
Forum: Photoelectric Effect
Topic: Calculating the number of photons [ENDORSED]
Replies: 2
Views: 54

Re: Calculating the number of photons [ENDORSED]

You can use the equation E=hv, which refers to the energy of a single photon of light. In this problem, you're asked how many photons have a total given amount of energy. You're given the wavelength of the photons, so you can convert to frequency, use E=hv to find the joules per photon (E), and then...
by MinuChoi
Thu Oct 10, 2019 8:51 pm
Forum: Limiting Reactant Calculations
Topic: Finding Limiting Reactant
Replies: 3
Views: 106

Re: Finding Limiting Reactant

The limiting reactant of a chemical reaction is the reactant that is completely consumed to make the product (some amount of the other reactants will be leftover, or in excess). Say you have two given amounts of reactant that undergo a chemical reaction to make products. Using the balanced chemical ...
by MinuChoi
Thu Oct 10, 2019 8:45 pm
Forum: Empirical & Molecular Formulas
Topic: M.5
Replies: 2
Views: 70

Re: M.5

If you're referring to the subtraction to find the leftover reagent, here's my work: Plug 12mol ClO2 into the equation to convert to mol BrF3 to determine how much BrF3 is consumed. According to the equation, 4mol BrF3 is consumed with 12mol ClO2. Subtract the 4mol BrF3 from the given 5mol BrF3 and ...
by MinuChoi
Thu Oct 10, 2019 8:27 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Balmer Series
Replies: 1
Views: 64

Re: Balmer Series

I believe for the Balmer series, n=2 is the lower quantum level for electrons. It can be the final or initial state (n1 or n2), depending on whether light is being absorbed or emitted; but the wavelengths of spectral lines involved are the same for absorption and emission.
by MinuChoi
Thu Oct 10, 2019 5:01 pm
Forum: Properties of Light
Topic: HW 1A.11
Replies: 1
Views: 36

Re: HW 1A.11

Says in the textbook that, for the equation, the lowest value of n is the same for all lines in one series. For the Balmer series, the number is 2; for the Lyman series, 1. The lower value of n is the lowest energy level of electrons involved in the spectral lines. And because there are significantl...
by MinuChoi
Thu Oct 10, 2019 4:45 pm
Forum: Empirical & Molecular Formulas
Topic: Homework F9
Replies: 4
Views: 81

Re: Homework F9

You can also try thinking of the decimals as fractions to help you decide what to multiply.
The decimals in the ratio for this problem are basically equivalent to thirds, so you would multiply by 3 to eliminate the fraction.
by MinuChoi
Thu Oct 03, 2019 3:49 pm
Forum: Empirical & Molecular Formulas
Topic: Law of Conservation of Mass?
Replies: 4
Views: 73

Re: Law of Conservation of Mass?

By the law of conservation of mass, total mass of reactants used equals total mass of product formed. The total reactants (A and B) used have a combined mass of 12g, but there are 14g of product formed. Mass is conserved in chemical reactions, so the product should be mass 12g. The given result is n...
by MinuChoi
Wed Oct 02, 2019 10:24 pm
Forum: Molarity, Solutions, Dilutions
Topic: Fundamental G.3 Concentration
Replies: 2
Views: 39

Re: Fundamental G.3 Concentration

You can convert micromoles to moles. The 1.44 micromoles of glucose is equal to 1.44x10^-6 moles of glucose. Now the units are more compatible with the molarity. Divide 1.44x10^-6 moles by the given 1.25x10^-3 mol/L measurement and the mole units will cancel out. [1.44x10^-6 moles]/[1.25x10^-3 mol/L...
by MinuChoi
Wed Oct 02, 2019 10:18 pm
Forum: Balancing Chemical Reactions
Topic: Fundamental H5 D
Replies: 3
Views: 45

Re: Fundamental H5 D

You can save balancing S for last, since it appears several times on one half of the equation.
And since S is its own particle on the reactants side, balancing S will be really easy once the Fe and P are balanced out.
by MinuChoi
Wed Oct 02, 2019 10:14 pm
Forum: Empirical & Molecular Formulas
Topic: 5 Homework Problems Due
Replies: 21
Views: 261

Re: 5 Homework Problems Due

Does anyone know if the homework is graded on correctness? If the work is partially wrong or if the answer is incorrect, do we receive a lower grade for the homework that week? There's nothing on the syllabus about how strictly the homework's graded, but given we have access to the solutions manual...
by MinuChoi
Wed Oct 02, 2019 2:54 pm
Forum: Balancing Chemical Reactions
Topic: Question H7a
Replies: 6
Views: 70

Re: Question H7a

Hydroxide has -1 charge because of oxidation numbers. O's oxidation number is -2 and H's oxidation number is -1. You can also think of when water ionizes; it splits into a hydrogen ion (acidic) and hydroxide ion (basic). Hydrogen ions have charge +1 and water is neutral charge, so hydroxide has char...

Go to advanced search