Search found 61 matches

by ThomasNguyen_Dis1H
Wed Jan 15, 2020 2:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: cubic equations
Replies: 2
Views: 11

Re: cubic equations

When K is less than 10^-3. You can also check at the end of the calculation to see if the change is less than 5% to see if the approximation works out.
by ThomasNguyen_Dis1H
Wed Jan 15, 2020 2:16 pm
Forum: Ideal Gases
Topic: equilibrium constant
Replies: 5
Views: 21

Re: equilibrium constant

K is an equilibrium constant that represents the ratio of products to reactants. There's different types of K like Kp, Kc, Ka, Kb, but they all function the same and represent the ratio of products over reactants. The subscripts specify what kind of equilibrium it is. For example, Kp is equilibrium ...
by ThomasNguyen_Dis1H
Wed Jan 15, 2020 2:13 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Calculating Q
Replies: 16
Views: 43

Re: Calculating Q

Q is calculated the same way as K so you include aqueous and gas in the calculation for Q
by ThomasNguyen_Dis1H
Wed Jan 15, 2020 2:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: strong vs weak
Replies: 4
Views: 13

Re: strong vs weak

Yes you can use Kw=pOH+pH and Kw=pKa+pKb
by ThomasNguyen_Dis1H
Wed Jan 15, 2020 2:11 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: strong vs weak
Replies: 4
Views: 13

Re: strong vs weak

Yes you can use Kw=pOH+pH and Kw=pKa+pKb
by ThomasNguyen_Dis1H
Wed Jan 15, 2020 2:09 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: x is small approximation
Replies: 6
Views: 26

Re: x is small approximation

When K is smaller than 10^-3 you can approximate x
by ThomasNguyen_Dis1H
Fri Jan 10, 2020 11:13 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units for K
Replies: 10
Views: 44

Re: Units for K

Because it is a constant and is just a value used to look at the equilibrium of the reaction
by ThomasNguyen_Dis1H
Fri Jan 10, 2020 11:12 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp vs Kc
Replies: 6
Views: 20

Re: Kp vs Kc

Use Kp for gases and Kc for aqueous reactants and products.
by ThomasNguyen_Dis1H
Fri Jan 10, 2020 11:12 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Calculating K
Replies: 6
Views: 29

Re: Calculating K

It would be the inverse of the concentration since K is products over reactants
by ThomasNguyen_Dis1H
Fri Jan 10, 2020 11:10 am
Forum: Ideal Gases
Topic: Difference between K and Q
Replies: 9
Views: 28

Re: Difference between K and Q

K is the equilibrium constant with the equilibrium values of the product and reactants. Q is used when the reaction is not at equilibrium and is used to predict what's favored as the reaction proceeds.
by ThomasNguyen_Dis1H
Wed Dec 04, 2019 12:19 pm
Forum: Identifying Acidic & Basic Salts
Topic: pH of salt solutions
Replies: 2
Views: 16

Re: pH of salt solutions

If the ion came from a strong acid or strong base, it will not affect the ph since the conjugates of these acids and bases are weak. Conjugates of weak acids and bases will affect the ph since they'll be strong acid and bases.
by ThomasNguyen_Dis1H
Wed Dec 04, 2019 12:14 pm
Forum: Hybridization
Topic: Hybridization of terminal atoms
Replies: 2
Views: 30

Re: Hybridization of terminal atoms

No you only need to know the hybridization of the central atoms.
by ThomasNguyen_Dis1H
Wed Dec 04, 2019 12:10 pm
Forum: Lewis Acids & Bases
Topic: HCl and HI
Replies: 10
Views: 42

Re: HCl and HI

HI, since I has a larger atom radius than Cl, HI has a weaker bond than HCl which makes HI dissociate completely very easily.
by ThomasNguyen_Dis1H
Wed Dec 04, 2019 12:05 pm
Forum: Amphoteric Compounds
Topic: H2O
Replies: 8
Views: 27

Re: H2O

Yes, water can act as a base or an acid
by ThomasNguyen_Dis1H
Wed Dec 04, 2019 12:02 pm
Forum: Amphoteric Compounds
Topic: amphoteric oxides
Replies: 3
Views: 16

Re: amphoteric oxides

Know which metal oxides are amphoteric. (BeO, Al2O3, Ga2O3, SnO2, Sb2O5, PbO2)
by ThomasNguyen_Dis1H
Sun Dec 01, 2019 8:06 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strong Acids
Replies: 3
Views: 21

Re: Strong Acids

Strong acids are acids that completely dissociate to completion (100%). These acids include HCl, HBr, HI, HNO3, H2SO4, and HClO4. They are strong acids because the have weak bonds and are able to dissociate completely which allows them to donate a proton.
by ThomasNguyen_Dis1H
Sun Dec 01, 2019 8:04 pm
Forum: Amphoteric Compounds
Topic: Amphoteric Compound
Replies: 5
Views: 29

Re: Amphoteric Compound

Amphoteric compounds are compounds that can act as both an acid and a base. In class he showed examples of acid and base reactions that involved water. Water can act as both an acid and a base as it can accept H+ to become H3O+ and donate H+ to become OH-. There are also a couple of nonmetal and met...
by ThomasNguyen_Dis1H
Sun Dec 01, 2019 8:01 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: Test Grades
Replies: 6
Views: 47

Re: Test Grades

The TA's will update it later most likely. If not then for sure by the end of the quarter when everything is finalized.
by ThomasNguyen_Dis1H
Sun Dec 01, 2019 8:00 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted Acid and Base
Replies: 5
Views: 23

Re: Bronsted Acid and Base

Yes. acids donate a proton while bases accept protons for bronsted definitions
by ThomasNguyen_Dis1H
Sun Dec 01, 2019 7:59 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sigma Bond
Replies: 10
Views: 39

Re: Sigma Bond

Yes they are. Sigma bonds are also in double and triple bonds.
by ThomasNguyen_Dis1H
Sun Nov 24, 2019 9:16 pm
Forum: Hybridization
Topic: hybridization
Replies: 5
Views: 36

Re: hybridization

Hybridization is the concept of combing orbitals so that an atom has space in their orbitals to hold bonding electrons.
by ThomasNguyen_Dis1H
Sun Nov 24, 2019 9:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: H3O+
Replies: 11
Views: 70

Re: H3O+

H30+ is tetrahedral since the O is bonded to 3 hydrogens and has a lone pair which makes the molecule have 4 electron densities. Since there's one lone pair the shape would be trigonal pyramidal.
by ThomasNguyen_Dis1H
Sun Nov 24, 2019 9:12 pm
Forum: Naming
Topic: Order in Naming
Replies: 12
Views: 56

Re: Order in Naming

Place the ligand names in alphabetical order and determine if the complex has a positive or negative charge to determine if you place it before or after a cation or an anion.
by ThomasNguyen_Dis1H
Sun Nov 24, 2019 9:10 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Transition Metals
Replies: 2
Views: 17

Re: Transition Metals

Transition metals have empty valance-shell orbitals that can accept pairs of electrons from ligands.
by ThomasNguyen_Dis1H
Sun Nov 24, 2019 9:08 pm
Forum: Hybridization
Topic: Shapes
Replies: 3
Views: 23

Re: Shapes

The shapes tell you how many bonds the central atom has with other atoms including lone pairs. With this knowledge, you can determine the hybridization of the central atom by making sure there are enough empty orbitals to make bonds with other atoms. For example NH3 has 4 electron density regions an...
by ThomasNguyen_Dis1H
Sat Nov 16, 2019 10:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar vs. Nonpolar
Replies: 12
Views: 79

Re: Polar vs. Nonpolar

First look at the molecular geometry that is 3D and draw dipole moments to see if they cancel out. You have to keep in mind that the geometry is 3 dimensional and take it into account when seeing if the dipoles cancel out.
by ThomasNguyen_Dis1H
Sat Nov 16, 2019 7:47 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2E.7 hw prob
Replies: 1
Views: 19

Re: 2E.7 hw prob

Since the shape of the molecule is a trigonal pyramidal, there's no difference in the bond angles between S-O-Cl. There's only one bond angle.
by ThomasNguyen_Dis1H
Sat Nov 16, 2019 7:45 pm
Forum: Dipole Moments
Topic: 2E. 25a
Replies: 2
Views: 20

Re: 2E. 25a

CH2CL2 has the molecular shape of a tetrahedral. Due to the nature of a tetrahedral, the Cl atoms will be right next to each other. You can imagine a tripod with another leg above it. No matter how you rotate this shape, Cl will be right next to another Cl. Since the dipole moments move towards both...
by ThomasNguyen_Dis1H
Sat Nov 16, 2019 7:41 pm
Forum: Bronsted Acids & Bases
Topic: Test2
Replies: 7
Views: 55

Re: Test2

Should mostly be VSEPR and Monday's topics. It will ask questions revolving around molecular shapes.
by ThomasNguyen_Dis1H
Fri Nov 08, 2019 12:26 pm
Forum: Quantum Numbers and The H-Atom
Topic: Quantum Numbers
Replies: 6
Views: 54

Re: Quantum Numbers

ms can only have the value of +/- 1/2. When drawing the electron configurations with arrows pointing up and down, you can see that each orbital can only have 2 arrows, one pointing up and one pointing down. This represents ms. One electron can have the value of 1/2 while the other electron has the v...
by ThomasNguyen_Dis1H
Fri Nov 08, 2019 12:22 pm
Forum: Lewis Structures
Topic: Exceptions to Octet Rule
Replies: 7
Views: 33

Re: Exceptions to Octet Rule

With an n value of 3, the value of l can be 2 which is the d subshell. Since they have access to d orbitals, they are able to hold extra electrons in this orbital.
by ThomasNguyen_Dis1H
Fri Nov 08, 2019 12:21 pm
Forum: Quantum Numbers and The H-Atom
Topic: Formal names for each letter
Replies: 5
Views: 61

Re: Formal names for each letter

N is principal quantum number (shell), l is angular momentum quantum number (subshell), ml is the magnetic quantum number (orbital), and ms is the spin.
by ThomasNguyen_Dis1H
Fri Nov 08, 2019 12:16 pm
Forum: Dipole Moments
Topic: Drawing Unpaired Electrons
Replies: 7
Views: 48

Re: Drawing Unpaired Electrons

Yes always draw lone pairs in the lewis structures.
by ThomasNguyen_Dis1H
Fri Nov 08, 2019 12:15 pm
Forum: Quantum Numbers and The H-Atom
Topic: n, l ,ml, ms
Replies: 13
Views: 118

Re: n, l ,ml, ms

ms can only equal +/- 1/2. Each electron in the orbital can only take one of the values. For example, in a Pz orbital, two electrons can be in this orbital. These electrons can't have the same ms values so one must be +1/2 and one must be -1/2.
by ThomasNguyen_Dis1H
Sat Nov 02, 2019 3:58 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charges
Replies: 3
Views: 21

Re: Formal Charges

Probably not when the question doesn't ask you to, but it doesn't hurt to especially when you're dealing with ions or weird structures.
by ThomasNguyen_Dis1H
Sat Nov 02, 2019 3:56 pm
Forum: Formal Charge and Oxidation Numbers
Topic: formal charge
Replies: 5
Views: 50

Re: formal charge

You should keep in mind formal charges when drawing lewis structures since they give you the most stable structure of the molecule. To calculate it you can just take the valance electrons the element has and subtract the number of lone pair electrons (dots) and the number of bonds the element forms ...
by ThomasNguyen_Dis1H
Sat Nov 02, 2019 3:52 pm
Forum: Resonance Structures
Topic: resonance hybrid vs resonance structure
Replies: 2
Views: 18

Re: resonance hybrid vs resonance structure

Resonance structure is when there is more than one way to draw a lewis structure (double or triple bonds). A resonance hybrid structure is basically a combination of all the resonance structure which is more a more accurate depiction of the structure.
by ThomasNguyen_Dis1H
Sat Nov 02, 2019 3:49 pm
Forum: Resonance Structures
Topic: Delocalization
Replies: 4
Views: 32

Re: Delocalization

Yup! Resonance structures basically mean that the electrons are shared between the entire molecule not just within the covalent bonds. It will be more clear when we learn about pi and sigma bonds.
by ThomasNguyen_Dis1H
Sat Nov 02, 2019 3:47 pm
Forum: General Science Questions
Topic: Can We Take The Final In Pencil?
Replies: 14
Views: 507

Re: Can We Take The Final In Pencil?

No the final has to be taken in pen. But I feel the same way. Usually I would just roughly do the work in pencil and then go over with pen. It takes a lot of time so I just use pencil on the questions that are more difficult.
by ThomasNguyen_Dis1H
Sun Oct 27, 2019 2:01 pm
Forum: Properties of Light
Topic: Value for C
Replies: 8
Views: 63

Re: Value for C

You can use either one. I like using 3x10^8 since its easier on my calculator. Either way .002 wouldn’t make a difference in your final answer.
by ThomasNguyen_Dis1H
Sat Oct 26, 2019 6:26 pm
Forum: Ionic & Covalent Bonds
Topic: Resonance (all bonds are a hybrid of different bonds)
Replies: 10
Views: 68

Re: Resonance (all bonds are a hybrid of different bonds)

You have to draw every combination of the molecule with a double headed arrow between each lewis structure. This shows that the structures can really be any of the combinations you drew. That's the most accurate way to draw it using lewis structures.
by ThomasNguyen_Dis1H
Sat Oct 26, 2019 6:24 pm
Forum: Ionic & Covalent Bonds
Topic: Expanded Valence Shells
Replies: 4
Views: 39

Re: Expanded Valence Shells

These elements are in the third period of the periodic table. This means that since n=3, ml can also be equal to 2 which is the d-orbital. These elements have access to the d-orbital and can hold some electrons in these orbitals.
by ThomasNguyen_Dis1H
Sat Oct 26, 2019 6:20 pm
Forum: Ionic & Covalent Bonds
Topic: "Delocalized" Electrons
Replies: 5
Views: 50

Re: "Delocalized" Electrons

For electrons to be delocalized, it means that the electrons are shared within the entire molecule. In the other examples we have seen,it has always been about electrons being shared between two atoms. For example, the electrons in CH4 are shared between each of the carbon and hydrogen bonds. Howeve...
by ThomasNguyen_Dis1H
Sat Oct 26, 2019 6:17 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic and Covalent Bonds
Replies: 4
Views: 27

Re: Ionic and Covalent Bonds

Ionic bonds occur within a metal and a nonmetal (Na and Cl in NaCl). The electrons have to be taken and transferred from one atom to another. Covalent bonds form between two nonmetals. (C and H in CH4) The atoms in this bond share their electrons.
by ThomasNguyen_Dis1H
Sun Oct 20, 2019 3:36 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: What does the H mean?
Replies: 9
Views: 46

Re: What does the H mean?

No, the h-bar is just h(Planck's constant) divided by 2*pi
by ThomasNguyen_Dis1H
Sun Oct 20, 2019 3:30 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: 1D. 25
Replies: 4
Views: 32

Re: 1D. 25

1D.25 Which of the following subshells cannot exist in an atom: (a) 2d; (b) 4d; (c) 4g; (d) 6f? Can someone please explain this problem to me? Sub-shells refer to the quantum number l. Since the rule for l is l=0,1,...,n-1 you can look at the n and l values and determine if the following subshells e...
by ThomasNguyen_Dis1H
Sun Oct 20, 2019 3:26 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Valence electrons
Replies: 4
Views: 14

Re: Valence electrons

You would have to include both the 4s orbital and 3d orbital in your count for valance electrons. Valance electrons determine the amount of bonds that is possible for the atom so since you have empty orbitals, they count towards your valance electron count.
by ThomasNguyen_Dis1H
Sun Oct 20, 2019 3:21 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Nodal Plane
Replies: 3
Views: 23

Re: Nodal Plane

It all boils down to the wave function. Nodal planes are planes that divide lobes of electrons. It's the area where the probability of an electron is also zero. Since the s orbital is just one lobe, there's no nodal plane.
by ThomasNguyen_Dis1H
Sat Oct 19, 2019 4:35 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Cr and Cu
Replies: 5
Views: 38

Re: Cr and Cu

Cr and Cu are considered exceptions to the Aufbau principle. Since having half-filled and full electron orbitals is more stable than a other electron configurations, the 4s electron moves down to the 3d orbital.
by ThomasNguyen_Dis1H
Sat Oct 19, 2019 4:16 pm
Forum: Quantum Numbers and The H-Atom
Topic: Correlation Between n and l
Replies: 6
Views: 51

Re: Correlation Between n and l

l gives the shape of the orbital and it's also called the sub-shell.
l=0: S orbital
l=1: P orbital
l=2: D orbital
l=3: F orbital
by ThomasNguyen_Dis1H
Fri Oct 11, 2019 1:12 pm
Forum: Balancing Chemical Reactions
Topic: Fractions
Replies: 20
Views: 184

Re: Fractions

It should always be expressed as a whole number. However, during the thermodynamics units, it would be beneficial to leave it as a fraction, but for now just express them as whole numbers.
by ThomasNguyen_Dis1H
Fri Oct 11, 2019 1:10 pm
Forum: SI Units, Unit Conversions
Topic: Showing work/ rearranging equations
Replies: 8
Views: 85

Re: Showing work/ rearranging equations

You can really do it anyway you prefer. It's just that when you rearrange the variables first and plug into your calculator all at once, you will get a more accurate answer and avoid rounding off at intermediate steps.
by ThomasNguyen_Dis1H
Fri Oct 11, 2019 12:34 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Accuracy and Precision
Replies: 8
Views: 69

Re: Accuracy and Precision

It will become more relevant in a lab setting. If multiple trials of an experiment doesn't produce precise values, it will let you know that there is a systematic error (errors that can be eliminated). If your data is not accurate it could be due to random error (error you cannot control).
by ThomasNguyen_Dis1H
Fri Oct 11, 2019 12:27 pm
Forum: Empirical & Molecular Formulas
Topic: Decimals to Whole Numbers
Replies: 6
Views: 111

Re: Decimals to Whole Numbers

It also helps if you don't round at each intermediate step. Just plug it all into your calculator at once. If you do come across a number like 3.1, + or - .2 should be sufficient enough to round down or up.
by ThomasNguyen_Dis1H
Fri Oct 11, 2019 12:20 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect Clarification
Replies: 3
Views: 22

Re: Photoelectric Effect Clarification

Light sources with short wavelengths would have a larger frequency since there is an inverse relationship between wavelength and frequency. Using the equation E=hv, since a higher frequency correlates to a higher energy level, the light is able to overcome the threshold energy (work function) needed...
by ThomasNguyen_Dis1H
Wed Oct 02, 2019 7:20 pm
Forum: Empirical & Molecular Formulas
Topic: Homework question M.17
Replies: 2
Views: 41

Re: Homework question M.17

The 1 came from the molar mass of H and the 17 came from the molar mass of OH. Knowing that the molar mass of X plus the molar mass of O plus the molar mass of H equals the total molar mass of XOH, you can subtract 17 from 125 to find the molar mass of X. You can do the same for HA and subtract 1 fr...
by ThomasNguyen_Dis1H
Wed Oct 02, 2019 1:59 pm
Forum: Empirical & Molecular Formulas
Topic: Rounding for Formulas
Replies: 8
Views: 95

Re: Rounding for Formulas

There really isn't any cutoff for rounding. It's best if you don't round in your intermediate steps and calculations. That way you have exact values which would make it more clear how many moles of each atom there are. I would say that rounding up from .9 is okay, but anything below that should be r...
by ThomasNguyen_Dis1H
Tue Oct 01, 2019 11:56 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Homework Problem E.15
Replies: 4
Views: 73

Re: Homework Problem E.15

For this problem, you're given the molar mass of a hydroxide. To find the molar mass of the missing metal, subtract the molar masses of the Oxygen and Hydrogen from 74.10 (remember that there are two of each). Now with the molar mass we can find on the periodic table that the mystery element is Ca. ...
by ThomasNguyen_Dis1H
Tue Oct 01, 2019 11:46 pm
Forum: Significant Figures
Topic: Question About Significant Figures and Rounding
Replies: 22
Views: 301

Re: Question About Significant Figures and Rounding

I think its all situational. Typically your final answer should be in the correct sig figs. For the steps leading up to the final answer, 3-4 decimal places should be sufficient enough.
by ThomasNguyen_Dis1H
Tue Oct 01, 2019 11:30 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactant Lecture Question
Replies: 5
Views: 52

Re: Limiting Reactant Lecture Question

It is possible, but highly unlikely. The only way this would occur is if the calculated moles of reactants produce a ratio that is equal to the ratio in the balanced equation. Usually this never happens since there will be an excess of some compound in a lab setting.

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