Search found 55 matches

Wed Dec 04, 2019 3:52 pm
Forum: Conjugate Acids & Bases
Topic: Conjugate Acids and Bases
Replies: 6
Views: 68

Re: Conjugate Acids and Bases

Conjugate acids and bases are bronsted acids and bases. They always appear in the same chemical reaction.
Wed Dec 04, 2019 3:48 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Application of oxidation number
Replies: 3
Views: 136

Re: Application of oxidation number

Oxidation number is also useful when looking at redox reactions.
Wed Dec 04, 2019 3:47 pm
Forum: Formal Charge and Oxidation Numbers
Topic: SO4
Replies: 3
Views: 138

Re: SO4

By putting the 4 oxygens around the sulfur, you immediately have an octet. If it comes without a charge, then don't add a charge.
Wed Dec 04, 2019 3:43 pm
Forum: Sigma & Pi Bonds
Topic: finding hybridizations
Replies: 2
Views: 109

Re: finding hybridizations

If the electron is taken from n=2, then it's represented as 2sp^3, etc. If it's taken from n=3, then 3sp^3, etc.
In general, you can just represent it with sp^3.
Wed Dec 04, 2019 3:41 pm
Forum: Ionic & Covalent Bonds
Topic: polarity of shapes
Replies: 4
Views: 159

Re: polarity of shapes

The bond angle would be less than the bond angles in a octahedral. The long pairs do affect the bond angle since they cause repulsion.
Tue Nov 26, 2019 12:10 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 9C.5
Replies: 1
Views: 31

Re: 9C.5

Polydentate is a ligand that binds at more than 1 site since it donates more than 1 e- pair.

You can draw out the lewis structure to figure out which atom has lone pairs.

a. 3, on the nitrogen atoms
b. 1 or 2 on oxygen atoms
c. not a polydentate
d. 2 on oxygen atoms
Tue Nov 26, 2019 12:07 pm
Forum: Naming
Topic: 9C.1
Replies: 6
Views: 112

Re: 9C.1

(a) Hexacyanoferrate (II) +2
(b) Hexaaminecobalt (III) +3
(c) Aquapentacyanocobalte (III) +3
(d) Pentaaminesulfatocobalt (III) +3
Tue Nov 26, 2019 12:06 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 9C.3
Replies: 4
Views: 82

Re: 9C.3

Since there is a space between potassium and hexacyanidochromate (III), it indicates that potassium is out of the bracket.

K3 [Cr(CN)6]
Tue Nov 26, 2019 12:03 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Shapes
Replies: 4
Views: 55

Re: Shapes

linear, square planar, tetrahedral, octahedral
Tue Nov 26, 2019 12:02 pm
Forum: Naming
Topic: Rules
Replies: 1
Views: 26

Re: Rules

1. Put the ligand name in alphabetical order then put the transition metal cation name. 2. Use prefix to indicate the number of ligands: mono, di, tri, tetra, penta, hexa 3. Add O to the end of anion name: for example Cyanide -> Cyano 4. If ligand has name with di, tri, tetra, or polydentate, then u...
Sat Nov 23, 2019 12:27 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: [Fe(CN)6]4-
Replies: 5
Views: 66

Re: [Fe(CN)6]4-

The total charge is given so that you can calculate the charge of the Fe ion. In this case, since the total charge of 4-, and CN has a charge of -1, the charge of the Fe ion is +2
Sat Nov 23, 2019 12:25 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Polydentate
Replies: 4
Views: 43

Polydentate

What exactly is a polydentate?
Sat Nov 23, 2019 12:23 pm
Forum: Lewis Acids & Bases
Topic: bronsted and lewis acids
Replies: 2
Views: 26

Re: bronsted and lewis acids

Bronsted acids are always lewis acids, but not all lewis acids are bronsted acids.
Sat Nov 23, 2019 12:22 pm
Forum: Lewis Acids & Bases
Topic: Lewis vs Bronsted
Replies: 2
Views: 42

Re: Lewis vs Bronsted

Also, although all bronsted acids are lewis acids, not all lewis acids are bronsted acids.
Sat Nov 23, 2019 12:21 pm
Forum: Lewis Acids & Bases
Topic: carboxyl group COOH
Replies: 3
Views: 33

Re: carboxyl group COOH

It dissociates partially to release hydrogen ions
Thu Nov 14, 2019 8:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Drawing Molecular Structures
Replies: 8
Views: 80

Re: Drawing Molecular Structures

You determine the VSEPR structure of the molecule first. Then you can use lines to represent atoms on the same plane with the paper, solid triangles as atoms coming towards you, and dashed lines as atoms going away from you.
Thu Nov 14, 2019 8:19 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Formula
Replies: 2
Views: 47

Re: VSEPR Formula

Essentially yes. The number of bonded electron pairs represents X, and the number of lone pairs represets E.

Notice that a single bond, double bond, and triple bond all count towards a single X.
Thu Nov 14, 2019 8:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Trigonal Pyramid vs Trigonal Planar
Replies: 6
Views: 78

Re: Trigonal Pyramid vs Trigonal Planar

Also the bond angle is different. Trigonal planar has bond angles of 120 while trigonal pyramidal has bond angles of around 107, so these two are absolutely different.
Thu Nov 14, 2019 8:15 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lewis Structures & VSEPR
Replies: 9
Views: 71

Re: Lewis Structures & VSEPR

Drawing lewis structures help you determine whether there are lone pairs or not, which influences the VSEPR structure. Thus to be safe, always draw out the VSEPR first.
Thu Nov 14, 2019 8:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: varying VSEPRs
Replies: 7
Views: 107

Re: varying VSEPRs

Nope, because VSEPR relies on the lowest energy Lewis structure.
Fri Nov 08, 2019 3:16 pm
Forum: Photoelectric Effect
Topic: Frequency and number of electrons ejected
Replies: 2
Views: 138

Frequency and number of electrons ejected

I know that to emit an electron, the photon has to reach a specific frequency. Is it true that the frequency of the photon has to double in order to emit the second electron?
Fri Nov 08, 2019 3:12 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: DNA
Replies: 3
Views: 50

DNA

Why are there 2 hydrogen bonds between A and T base pairs?
Fri Nov 08, 2019 3:11 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: 44

Hydrogen bonding

Does the H of H2O and O of CO form a hydrogen bond?
Fri Nov 08, 2019 3:08 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical formula
Replies: 3
Views: 157

Re: Empirical formula

Remember that the key is to find the molar ratio of the elements. You find the number of moles of CO2, for example, through dividing the given grams by molar mass. This number of moles of CO2 is also the number of moles of C, since there is only 1 C atom in one CO2 molecule. For H2O, you need to tim...
Fri Nov 08, 2019 3:01 pm
Forum: Properties of Light
Topic: Work Function
Replies: 2
Views: 128

Re: Work Function

Another way to think about it is that work function is the threshold energy need to emit one single electron from the metal. Thus the single photon needs to possess an adequate amount of energy, or at least the threshold energy.
Sat Nov 02, 2019 12:14 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Energy change and Energy of photon
Replies: 5
Views: 55

Energy change and Energy of photon

If a hydrogen atom goes from n=3 to n=1, why is the change in energy negative and why is the energy of the photon emitted positive?
Sat Nov 02, 2019 12:12 pm
Forum: DeBroglie Equation
Topic: Question about Converting Units
Replies: 3
Views: 67

Re: Question about Converting Units

1keV = 1000 eV
1 eV = 1.60e-19 J

so 1keV = 1000 x 1.60e-19 J
Sat Nov 02, 2019 12:08 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg Indeterminacy Equation
Replies: 6
Views: 228

Heisenberg Indeterminacy Equation

Where does the 4 pi come from in the equation?
Sat Nov 02, 2019 12:05 pm
Forum: Photoelectric Effect
Topic: Work Function
Replies: 6
Views: 74

Work Function

What exactly is the definition of work function? If it's the energy needed to remove a single electron from solid metal, why is the unit sometimes J per mole?
Sat Nov 02, 2019 12:01 pm
Forum: Properties of Light
Topic: Waves
Replies: 4
Views: 85

Re: Waves

As long as it's greater than 10^-15 m, then it's considered to have measurable wavelike properties.
Fri Oct 25, 2019 2:36 pm
Forum: Lewis Structures
Topic: Drawing Lewis Structures
Replies: 8
Views: 87

Re: Drawing Lewis Structures

Hydrogen in some cases has lower ionization energy than other atoms. But it's almost never used as the central atom, except if the molecule is H2.
Fri Oct 25, 2019 2:33 pm
Forum: Lewis Structures
Topic: Homework 2B.3 d
Replies: 2
Views: 45

Re: Homework 2B.3 d

First of all, BrF3 has a total of 28 valence electrons, instead of 24. Br has a lower ionization energy than F, so Br is the central atom. Each F-Br bond constitutes to 2 electrons, so that's a total of 6, and you still need to assign the rest of the 22 valence electrons. Put 4 electrons on Br so th...
Fri Oct 25, 2019 2:29 pm
Forum: Lewis Structures
Topic: Charges on atoms with lower e- affinity
Replies: 4
Views: 43

Re: Charges on atoms with lower e- affinity

And by charge, he meant the calculated formal charge.
Fri Oct 25, 2019 2:17 pm
Forum: Octet Exceptions
Topic: Octet exception examples
Replies: 9
Views: 128

Re: Octet exception examples

also P, S, Cl may exceed the octet rule
Fri Oct 25, 2019 2:16 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Electron Affinity and Formal Charge
Replies: 3
Views: 48

Re: Electron Affinity and Formal Charge

Basically put the negative charge on the atom with the highest electron affinity
Thu Oct 17, 2019 10:01 pm
Forum: Properties of Light
Topic: atomic spectra
Replies: 2
Views: 31

Re: atomic spectra

c = wavelength x frequency c= speed of light wavelength = 1850 nm (be sure to convert it to meters) You will get frequency. Plug the frequency value into E=hv, where h is planck's constant. You will get the energy of a single photon. Then use the total number of Energy, which is 11J, divide it by th...
Thu Oct 17, 2019 9:56 pm
Forum: Properties of Light
Topic: 1A.9 Energy of Photon
Replies: 12
Views: 144

Re: 1A.9 Energy of Photon

E = hv

So after u calculate v from c=wavelength x frequency, u plug it into E=hv with h as Planck's constant
Thu Oct 17, 2019 9:55 pm
Forum: *Shrodinger Equation
Topic: Nodal Planes
Replies: 6
Views: 66

Nodal Planes

How many nodal planes do f orbitals have?
Thu Oct 17, 2019 9:54 pm
Forum: *Shrodinger Equation
Topic: Psi ^2
Replies: 2
Views: 32

Psi ^2

I know that psi represents the height of a wave at position x,y, z. But I don't understand why psi^2 represents the probability of finding an e-.
Thu Oct 17, 2019 9:51 pm
Forum: *Shrodinger Equation
Topic: Quantum Number
Replies: 2
Views: 66

Quantum Number

If Schrodinger wave equation with 3 quantum numbers can only be used to solve for 1 e- atoms, then can you use 4 quantum numbers to solve for more electrons since the fourth number indicates the spin state?
Wed Oct 09, 2019 4:11 pm
Forum: Significant Figures
Topic: %Mass Composition
Replies: 12
Views: 323

%Mass Composition

If we're asked to calculate the %mass composition of a compound, how many sig figs should we keep?
Wed Oct 09, 2019 4:08 pm
Forum: Quantum Numbers and The H-Atom
Topic: Atomic Spectra
Replies: 5
Views: 59

Re: Atomic Spectra

Yea, as long as they are spectra of the same atom.
Wed Oct 09, 2019 3:58 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Equation Question
Replies: 2
Views: 84

Re: Equation Question

Also this equation only applies to the H-atom
Wed Oct 09, 2019 3:55 pm
Forum: Photoelectric Effect
Topic: Atomic Spectra [ENDORSED]
Replies: 3
Views: 57

Re: Atomic Spectra[ENDORSED]

It is grouped by the type of electromagnetic radiation or wavelength/frequency that is shone on the material. Thus it is grouped as UV, infrared, and visible and since they have different energies, the electrons will return to different shells.
Wed Oct 09, 2019 3:48 pm
Forum: Photoelectric Effect
Topic: E=hv
Replies: 1
Views: 49

E=hv

If the question asks that a certain amount of energy is needed to remove 1 mole of electrons, you first divide the energy by Avogadro's number before proceeding to the rest of the calculation right?
Sat Oct 05, 2019 6:13 pm
Forum: Molarity, Solutions, Dilutions
Topic: Which Volume to use for M1
Replies: 6
Views: 83

Re: Which Volume to use for M1

The first volume given usually allows you to calculate the molarity. Typically we use the second volume in the calculation.
Sat Oct 05, 2019 6:10 pm
Forum: Limiting Reactant Calculations
Topic: Explaining why a reactant is limiting
Replies: 4
Views: 98

Re: Explaining why a reactant is limiting

I would write down my calculation first: 0.3moles / 2 = 0.15moles of B 0.2 moles /1 = 0.2 moles of A. Since 0.15 moles of B is less than 0.2 moles of A, B is the limiting reactant. I think your explanation is also acceptable, as long as you explain that since we only have .3 moles of B right now and...
Sat Oct 05, 2019 6:03 pm
Forum: Empirical & Molecular Formulas
Topic: Combustion Analysis
Replies: 6
Views: 121

Re: Combustion Analysis

A combustion analysis allows you to deduce the formula of an organic compound, which is usually CxHy or CxHyOz. It can also be used to determine the percentage purity by mass of a given compound.
Sat Oct 05, 2019 6:01 pm
Forum: Empirical & Molecular Formulas
Topic: Is there an easier way to figure out which integer to multiply the number of atoms with to get a whole number?
Replies: 4
Views: 68

Re: Is there an easier way to figure out which integer to multiply the number of atoms with to get a whole number?

You can convert it to a fraction first (using your calculator) then just multiply by the denominator.
Sat Oct 05, 2019 6:00 pm
Forum: Empirical & Molecular Formulas
Topic: Combustion Analysis
Replies: 1
Views: 120

Combustion Analysis

Hey guys Im confused about M.26. It states that a combustion analysis of the compound C14H20O2N gave the following data: 68.50%C, 8.18%H by mass. Because the data were considerably different from that expected for pure C14H20O2N, the sample was examined and found to contain a significant amount of C...
Sat Sep 28, 2019 4:32 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Avogradro's Number [ENDORSED]
Replies: 5
Views: 359

Avogradro's Number[ENDORSED]

So I was doing E5 on the textbook and it asks how many moles of people inhabit Earth if the estimated population is 7.0 billion people. This made me question the definition of 1 mole and Avogadro's number.
Sat Sep 28, 2019 4:27 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: MOLARITY
Replies: 17
Views: 1040

Re: MOLARITY

Does anyone know the difference between molarity and molality?
Sat Sep 28, 2019 4:23 pm
Forum: Molarity, Solutions, Dilutions
Topic: mass of solute
Replies: 3
Views: 44

Re: mass of solute

Becuz ur asked to prepare a solution. When copper (ii) sulfate pentahydrate is dissolved in water, the attached H2O joins with the surrounding water. Since copper (ii) sulfate pentahydrate contains 1 mole of CuSO4, the amount of copper (ii) sulfate pentahydrate you need is the same as the amount of ...
Sat Sep 28, 2019 4:10 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Formula Unit
Replies: 7
Views: 228

Formula Unit

Could someone please explain the difference between a formula unit and a molecule? Thanks.
Sat Sep 28, 2019 4:03 pm
Forum: Significant Figures
Topic: How does Significant Figures work? [ENDORSED]
Replies: 12
Views: 239

Re: How does Significant Figures work?[ENDORSED]

In inter-problem calculations, how many sig figs do u keep? Same as the question or one more?

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