Search found 76 matches

by 805422680
Mon Feb 10, 2020 11:07 am
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: W
Replies: 4
Views: 25

Re: W

W is degeneracy. It is equal to the number of states raised to the number of species
by 805422680
Mon Feb 10, 2020 11:06 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Exothermic reactions
Replies: 5
Views: 19

Re: Exothermic reactions

Spontaneous processes have an increase in entropy. Delta H will be negative and S will be positive. Therefore G will be negative and hence the process is spontaneous
by 805422680
Mon Feb 10, 2020 11:04 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Is heat capacity/specific heat capacity a state function?
Replies: 2
Views: 12

Re: Is heat capacity/specific heat capacity a state function?

Heat capacity is a state function as the method to attain the heat capacity of a system is the sum of each component part of the system
by 805422680
Mon Feb 10, 2020 11:03 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Spontaneity and Entropy
Replies: 3
Views: 13

Re: Spontaneity and Entropy

An increase in entropy leads to a decrease in Gibbs free energy. Both these situations represent a spontaneous reaction
by 805422680
Mon Feb 10, 2020 11:02 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated vs Insulated
Replies: 3
Views: 10

Re: Isolated vs Insulated

If a system is well insulated enough, it can be considered to be isolated ie there is no transfer of heat or energy
by 805422680
Mon Feb 03, 2020 1:07 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed vs isolated?
Replies: 7
Views: 21

Re: closed vs isolated?

Closed systems are those that can exchange energy not matter with the surroundings. Isolated systems, on the other hand, can exchange neither with the surroundings. Examples of a closed system include a sealed container (that is capable of transmitting heat etc.), and examples of an isolated system ...
by 805422680
Mon Feb 03, 2020 1:05 am
Forum: Calculating Work of Expansion
Topic: Reversible
Replies: 7
Views: 14

Re: Reversible

reversible means that even if there is an infinitesimal change in the system, there will be a significant change in the behavior of the system. the definitions of reversible in equilibrium reactions and thermodynamically, however, differ greatly.
by 805422680
Mon Feb 03, 2020 1:03 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: enthalpy
Replies: 7
Views: 19

Re: enthalpy

Enthalpy is the total amount of heat within a system.
by 805422680
Mon Feb 03, 2020 1:02 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: taking phase change into account
Replies: 5
Views: 15

Re: taking phase change into account

it is taken into account when energy is first required to change the state of matter and then heat the new phase. therefore for example the heating of water from ice takes into account the energy required to melt the ice and then raise the temperature of water.
by 805422680
Mon Feb 03, 2020 12:59 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Double bonds
Replies: 4
Views: 20

Re: Double bonds

The conversion from a double bond to a single bond is a new bond being formed. for organic compounds for example it could be a C-H bond forming. the bond enthalpies of C=O and C-O + C-H are different.
by 805422680
Mon Feb 03, 2020 12:58 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Standard Reaction Enthalpy
Replies: 4
Views: 12

Re: Standard Reaction Enthalpy

Enthalpy change of formation is the energy of reactants and products in their most stable state. Enthalpy change of reaction is the difference in those enthalpies
by 805422680
Sun Jan 26, 2020 9:53 pm
Forum: Phase Changes & Related Calculations
Topic: Enthalpy is said to be additive
Replies: 10
Views: 35

Re: Enthalpy is said to be additive

enthalpies of different reactions can be added together to get the total enthalpy of the system in its change from reactants to products
by 805422680
Sun Jan 26, 2020 9:52 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Weak acid/base
Replies: 14
Views: 42

Re: Weak acid/base

if the Ka value is high, or the pKa value is low, the acid is generally a strong acid and vice versa for a weak acid. this is also true for Kb and bases
by 805422680
Sun Jan 26, 2020 9:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: hess's law
Replies: 5
Views: 17

Re: hess's law

the total enthalpy of the system remains the same regardless of the route taken to reach the final product. this is important when the reaction from reactants to products in one step is energetically or chemically unfavorable
by 805422680
Sun Jan 26, 2020 9:48 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: removing H2 from N2 + 3H2 -> 2NH3
Replies: 7
Views: 26

Re: removing H2 from N2 + 3H2 -> 2NH3

according to le chatelier's principle, a system works to minimize the effect of the change. therefore there will be an increase in the rate of the reverse reaction, and there will be H2 formed until it reached the required level
by 805422680
Wed Jan 22, 2020 10:01 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Ice Box
Replies: 9
Views: 48

Re: Ice Box

For an ICE box problem, the change would always be subtracted on the reactants side and added on the products side.
by 805422680
Mon Jan 13, 2020 11:39 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Q
Replies: 10
Views: 26

Re: Q

Q is the composition of a system at any time (even those other than equilibrium). It is an important indicator that tells you whether equilibrium lies in favor of products or reactants. when Q < K, the reaction will move toward the products, and if Q > K, the reaction will move towards the reactants...
by 805422680
Mon Jan 13, 2020 11:34 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kw and H3O/OH concentrations
Replies: 5
Views: 15

Re: Kw and H3O/OH concentrations

the Kw of water remains constant at a given temperature, although the concentrations of hydronium and hydroxide ions can vary. for example, in an acidic solution if [H3O+] is say 1.00 x 10^-2, then using the Kw, we can conclude that the [OH-] is 1.00 x 10^ -12.
by 805422680
Mon Jan 13, 2020 11:31 pm
Forum: Ideal Gases
Topic: When to use this equation
Replies: 14
Views: 68

Re: When to use this equation

PV= nRT is used for ideal gases only. if concentrations and Kp are given, this equation can be used to calculate the partial pressure of products and reactants and vice versa, if partial pressures are given, concentrations can be calculated using this method
by 805422680
Mon Jan 13, 2020 11:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Units for K
Replies: 21
Views: 57

Re: Units for K

K does not have units as it is a constant value of the ratio of concentrations of products to reactants.
by 805422680
Mon Jan 13, 2020 11:28 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5J.5
Replies: 4
Views: 20

Re: 5J.5

the H2 molecule has been omitted from the right side of the equation. if it were present, the number of molecules would be the same on the right and the left of the equation, therefore, there'd be no change in equilibrium as a result of a change in pressure.
by 805422680
Mon Jan 13, 2020 11:26 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6B.5d
Replies: 2
Views: 14

Re: 6B.5d

find moles of OH- ions in 2ml of 0.175M KOH. Divide this value to obtain concentration of OH- ions. use the formula of pOH to calculate the pOH of solution and then subtract by 14 to calculate the pH
by 805422680
Mon Jan 13, 2020 11:24 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Effect of Inert Gases
Replies: 9
Views: 29

Re: Effect of Inert Gases

Inert gases generally do not react, therefore, it is unlikely that their presence will change the reaction mixture at all.
by 805422680
Mon Jan 13, 2020 11:22 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Concentrations and the K value.
Replies: 7
Views: 30

Re: Concentrations and the K value.

the stochiometric coefficients show the number of molecules of one type reacting together. therefore, if the equation is 2H20----> H3O+ + OH-, two water molecules react to give one H3O+ molecule and one OH- molecule. concentrations of products are multiplied and divided by reactants to the give the ...
by 805422680
Mon Jan 13, 2020 11:19 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 6A21
Replies: 2
Views: 20

Re: 6A21

The concentrations of H3O+ and OH- are equal in water. therefore, using the new value of Kw as 2.1x10^-14, square root it to get concentrations of H3O+ and OH-
by 805422680
Mon Jan 13, 2020 11:17 pm
Forum: Ideal Gases
Topic: ICE tables
Replies: 9
Views: 47

Re: ICE tables

The ICE box is used for concentrations to calculate the concentration of reactants and products at equilibrium given a Kc value. If there is a Kp value given, then pressure in the units atm will be used.
by 805422680
Mon Dec 09, 2019 12:06 am
Forum: Naming
Topic: -ate
Replies: 10
Views: 70

Re: -ate

The -ate is only added for a negatively charged ion. For neutral and positively charged ion, just the metal name is required
by 805422680
Mon Dec 09, 2019 12:06 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Nitro vs Nitrito
Replies: 6
Views: 44

Re: Nitro vs Nitrito

NO2- is nitro and ONO is nitrito
by 805422680
Mon Dec 09, 2019 12:04 am
Forum: Student Social/Study Group
Topic: most stable
Replies: 6
Views: 42

Re: most stable

It means a formal charge of 0 on most atoms.
by 805422680
Mon Dec 09, 2019 12:04 am
Forum: *Titrations & Titration Calculations
Topic: Types of Titrations
Replies: 2
Views: 46

Re: Types of Titrations

Acid-Base titrations are the only ones that we need to know as of now. Other examples are red-ox titration
by 805422680
Mon Dec 09, 2019 12:03 am
Forum: Hybridization
Topic: Identifying Hybrid Orbitals
Replies: 5
Views: 34

Re: Identifying Hybrid Orbitals

To find a hybrid orbital, look at the number of regions of electron density around the atom. If there are 2, the hybridisation will be sp, if there are 3, sp2, 4 = sp3, 5= sp3d, 6=sp3d2
by 805422680
Sun Dec 01, 2019 5:15 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: structure of water
Replies: 4
Views: 26

Re: structure of water

This is because of the orientation of the lone pairs of electrons in water. Only one can have the correct orientation to bond.
by 805422680
Sun Dec 01, 2019 5:13 pm
Forum: Hybridization
Topic: 2F.3
Replies: 3
Views: 21

Re: 2F.3

This is because the formal charge of the second structure is lower due to the presence of resonant structures.
by 805422680
Sun Dec 01, 2019 5:11 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: HW 9C.7
Replies: 1
Views: 20

Re: HW 9C.7

Something can be a chelating compound when it forms a ring with the metal being a part of it. The answer to your question is the one where the NH3's are closest to each other.
by 805422680
Sun Dec 01, 2019 5:08 pm
Forum: Lewis Acids & Bases
Topic: BF3
Replies: 2
Views: 20

Re: BF3

BF3 is a lewis acid because it is electron deficient and has empty orbitals. Therefore it is an electron acceptor.
by 805422680
Sun Dec 01, 2019 5:07 pm
Forum: Lewis Acids & Bases
Topic: strong and weak acids
Replies: 3
Views: 21

Re: strong and weak acids

You should know at least some common acids such as hydrochloric acid, sulphuric acid as strong acids, and acetic acid as a weak acid. You should be alright if you're familiar with the examples he went over in lecture. You can tell a base is a strong base if it dissociates completely in solution to f...
by 805422680
Sun Nov 24, 2019 1:08 pm
Forum: Hybridization
Topic: Concept
Replies: 3
Views: 31

Re: Concept

For hybridization, you are just mixing orbitals, to form new orbitals with different shape, size and energy than the component orbitals. This is energetically favorable for the formation of bonds and therefore explains why atoms such as carbon form 4 covalent bonds.
by 805422680
Sun Nov 24, 2019 1:05 pm
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: Bronsted vs. Lewis Acids
Replies: 9
Views: 42

Re: Bronsted vs. Lewis Acids

The definition of an acid varies in both cases. Bronsted focuses on protons. A Bronsted acid is therefore a proton donor. However, Lewis focuses on electrons, and a lewis acid is an electron acceptor.
by 805422680
Sun Nov 24, 2019 1:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angle of bent
Replies: 17
Views: 85

Re: Bond Angle of bent

This depends on whether the atom has one or two lone pairs, in addition to its two bond pairs. If it has one lone pair, the bond angle will be < 120 degrees, however, if it has two lone pairs, it will have a bond angle << 109.5 degrees (ex. Water has a bond angle of approx. 104.5 degrees)
by 805422680
Sun Nov 24, 2019 1:00 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Charges
Replies: 4
Views: 39

Re: Charges

No, you can look at the position of the atom on the periodic table and see how many electrons it needs to gain or lose to attain the electronic configuration of the closest noble gas. You will need to make sure that this is energetically favorable. Ex. A sodium atom would rather lose one electron th...
by 805422680
Sun Nov 24, 2019 12:57 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Coordination Compound
Replies: 3
Views: 30

Re: Coordination Compound

A coordination compound is one that contains a coordination complex within it. It is when the anions are bonded to the metal via coordinate covalent bonds,where both electrons are donated via the metal atom.
by 805422680
Sun Nov 17, 2019 2:22 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Van Der Waals Interaction
Replies: 11
Views: 52

Re: Van Der Waals Interaction

Yes, all molecules regardless of their polarity or non-polarity experience Van Der Waals interactions due to shift in the electron cloud density. The order of interaction from strongest to weakest is ion-dipole, dipole-dipole, dipole-induced dipole, induced dipole-induced dipole.
by 805422680
Sun Nov 17, 2019 2:20 am
Forum: Determining Molecular Shape (VSEPR)
Topic: London dispersion forces and vander waals
Replies: 5
Views: 37

Re: London dispersion forces and vander waals

An example for a Van der Waals interaction would be between N2 molecules. They do not have an inherent dipole moment beween the two atoms as they are identical, however, there is an instantaneous dipole created due to a shift in the electron density distribution, which thereby induces a dipole momen...
by 805422680
Sun Nov 17, 2019 2:15 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles with Different Atoms
Replies: 4
Views: 49

Re: Bond Angles with Different Atoms

CCl4 is a non-polar molecule as the dipole moments of each of the C-Cl bonds cancel each other out, as they are in exactly opposite directions. However, for the molecule CCl3F, there will be a dipole moment generated in the direction of the fluorine atom, due to its high electronegativity. Bond angl...
by 805422680
Sun Nov 17, 2019 2:10 am
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Formula
Replies: 7
Views: 31

Re: VSEPR Formula

Although while naming the molecule, the lone pairs of electrons do not matter, they do influence the molecular geometry of the molecule, and thus change bond angles due to their presence or absence. Each lone pair of electrons represents one region of electron density.
by 805422680
Sun Nov 17, 2019 2:07 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Large Molecules
Replies: 2
Views: 19

Re: Large Molecules

We can consider any of the carbon atoms to be the central atom in this case, and look at the regions of electron density around each one individually. This will also determine the bond angles in each part of the hydrocarbon.
by 805422680
Sun Nov 10, 2019 12:47 am
Forum: Bond Lengths & Energies
Topic: Shape of Molecules and bond strength
Replies: 5
Views: 27

Re: Shape of Molecules and bond strength

The shape of the molecule determines the bond strength as a more branched structure (such as 2,2- dimethylpropane) have smaller surface areas. As the intermolecular attractive forces are determined by this, the forces as stronger. Whereas for straight molecules, it is the opposite.
by 805422680
Sun Nov 10, 2019 12:41 am
Forum: Bond Lengths & Energies
Topic: negative Ep
Replies: 5
Views: 40

Re: negative Ep

This is because the charges on both the atoms are different i.e. one is positive and the other is negative. When using the equation to calculate Ep, you are multiplying both the charges on the atoms (q1.q2/r^2). Since multiplying a negative by a positive, will always give you a negative answer, Ep i...
by 805422680
Sun Nov 10, 2019 12:35 am
Forum: Dipole Moments
Topic: Van Der Waals
Replies: 5
Views: 44

Re: Van Der Waals

All molecules generally possess Van Der Waals forces due to the varying electron density distribution that occurs as a result of the electron cloud moving which temporarily creates a dipole, which can then induce other surrounding molecules to form dipole moments in them.
by 805422680
Sun Nov 10, 2019 12:32 am
Forum: Dipole Moments
Topic: Limits to Hydrogen Bonds
Replies: 1
Views: 15

Re: Limits to Hydrogen Bonds

This is due to the high electronegativity of the elements N, O and F. This results in a partial negative charge that attracts hydrogen which has a partial positive charge. It is also due to the lone pairs of electrons present around these atoms in a covalent bond.
by 805422680
Sun Nov 10, 2019 12:28 am
Forum: Ionic & Covalent Bonds
Topic: covalent relationship to polarizability
Replies: 4
Views: 29

Re: covalent relationship to polarizability

High polarizability and high polarizing power are when the electrons in an ionic bond can be distorted. This distortion is a result of the positively charged cation attracting negatively charged electrons. As this resembles the shared characteristic that electrons in a covalent bond face, it is cons...
by 805422680
Sun Nov 03, 2019 12:13 am
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 9
Views: 52

Re: Lewis Structures

The one with the lowest energy will always be correct so it safer to draw that and all it’s resonant structures.
by 805422680
Sun Nov 03, 2019 12:11 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: 4pi?
Replies: 2
Views: 48

Re: 4pi?

This is because the actual equation of h bar divided by 2. However h bar has a value of h/2 pi, therefore giving you h/4 pi
by 805422680
Sun Nov 03, 2019 12:09 am
Forum: Ionic & Covalent Bonds
Topic: Bond Strength
Replies: 3
Views: 26

Re: Bond Strength

It is because of the size of the fluoride and chloride ion too. The fluoride ion is smaller than the chloride ion as size of an ion increases down a group. Therefore, the electrons are held more closely and hence, the bond is stronger.
by 805422680
Sun Nov 03, 2019 12:07 am
Forum: Electronegativity
Topic: What is isoelectronic?
Replies: 13
Views: 55

Re: What is isoelectronic?

Isoelectronic means atoms or ions that have the same number of electrons. An example of this would be Na+, Mg2+
by 805422680
Sun Nov 03, 2019 12:04 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Loss from 4s over 3d?
Replies: 4
Views: 27

Re: Loss from 4s over 3d?

After the 3D orbital is filled, it falls to a lower energy than the 4s orbital. Therefore, since electrons are first lost from the highest energy shell or valence shell first, the 4s orbital loses electrons before the 3D orbital.
by 805422680
Sun Oct 27, 2019 3:35 pm
Forum: Ionic & Covalent Bonds
Topic: Double and single bond lengths
Replies: 6
Views: 35

Re: Double and single bond lengths

The double bond consists of two types of bonds, the pi bond and the sigma bond. The sigma bond is stronger than the pi bond which results in a shorter bond length. As for a triple bond, there are two pi bonds and one sigma bond, which results in an even shorter bond length.
by 805422680
Sun Oct 27, 2019 3:30 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Expanded Valence Shells
Replies: 1
Views: 30

Re: Expanded Valence Shells

For Chemistry 14A, those are the only elements we need to know follow the expanded octet rule. However, any element in Period 3 or later can generally experience an expanded octet due to the presence of the additional d and f subshells that get filled at higher energy levels.
by 805422680
Sun Oct 27, 2019 3:15 pm
Forum: Ionic & Covalent Bonds
Topic: Benzene's covalent bond
Replies: 2
Views: 26

Re: Benzene's covalent bond

Benzene has two possible resonant structures, with alternating double and single covalent bonds between Carbon atoms. On account of this variability in the density of the electron cloud, there is known to be a stable cloud of electrons on either side of the benzene molecule. Thus, this provides grea...
by 805422680
Sun Oct 27, 2019 3:12 pm
Forum: Trends in The Periodic Table
Topic: 1F.3
Replies: 3
Views: 28

Re: 1F.3

You have to know that a higher negative charge means that there are more electrons added to the atom to achieve stability. There is greater electron-electron repulsion when electrons are added to the valence shell. As you move left to right across the periodic table, the atomic radius decreases. By ...
by 805422680
Sun Oct 27, 2019 3:06 pm
Forum: Resonance Structures
Topic: Resonance
Replies: 8
Views: 42

Re: Resonance

Resonant structures show all the possible orientations the electrons can take within a molecule. All resonant structures are virtually the same. They exist only because of the electron density shifting.
by 805422680
Sat Oct 19, 2019 4:27 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Cr and Cu
Replies: 5
Views: 40

Re: Cr and Cu

Cu and Cr do not follow the traditional Aufbau principle as half or fully filled d-orbitals are at a higher energy than s orbitals. This is done to reduce electron-electron repulsion within the orbital.
by 805422680
Sat Oct 19, 2019 4:24 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Outer electrons
Replies: 2
Views: 33

Re: Outer electrons

Yes, this is due to electron shielding. Electron shielding results in a lower effective nuclear charge on the valence electrons and thus explains why valence electrons take part in chemical reactions.
by 805422680
Sat Oct 19, 2019 4:18 pm
Forum: Properties of Electrons
Topic: Photo and electron energy
Replies: 4
Views: 27

Re: Photo and electron energy

The electron will only absorb energy equal to the energy difference between two energy levels. Therefore if the energy is greater than the energy difference, the photon will not be absorbed unless the excess energy can be released in another way (eg. lattice vibration). However, assuming this is not...
by 805422680
Sat Oct 19, 2019 4:11 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Aufbau
Replies: 3
Views: 24

Re: Aufbau

The Aufbau Principle states that the orbitals with the lower energy level get filled with electrons before the higher energy level. Thus, this gives us information about the electronic configuration of the atom.
by 805422680
Sat Oct 19, 2019 4:08 pm
Forum: Quantum Numbers and The H-Atom
Topic: Correlation Between n and l
Replies: 6
Views: 55

Re: Correlation Between n and l

l indicates the azimuthal quantum number of an element that denotes the subshells the element contains;
l=0 signifies the s orbital (with a possible value of 0)
l=2 signifies the p orbital (with possible values of -1,0,1)
l=3 signifies the d orbital ( with possible values of -2, -1, 0, 1, 2)
by 805422680
Sat Oct 12, 2019 10:22 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Post Module Assessment: Experiment names
Replies: 2
Views: 33

Re: Post Module Assessment: Experiment names

The answer for #13 would be C. Atomic absorption spectroscopy; Absorption line spectrum, as this question asks about absorption, and the process of finding the spectrum of the compound out is called Atomic absorption spectroscopy, and this produces an Absorption line spectrum. The answer for #14 wou...
by 805422680
Sat Oct 12, 2019 10:18 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Atomic Spectra Video Module
Replies: 1
Views: 43

Re: Atomic Spectra Video Module

In 1m there are 1650763.73 wavelengths of krypton-86. There by dividing 1m by 1650762.72 wavelengths, the wavelength of each wave can be calculated to be 605.8nm. Thus, this falls under the visible spectrum. The energy can then be calculated by using the equation c=\nu \lambda , followed by the equa...
by 805422680
Sat Oct 12, 2019 10:11 pm
Forum: DeBroglie Equation
Topic: De Broglie Equation
Replies: 2
Views: 13

Re: De Broglie Equation

The De Broglie cannot be used for light as light or photons are considered to massless, and thus any answer that you would get from that equation would be zero. The De Broglie equation can only be used for objects with a small mass and high frequency.
by 805422680
Sat Oct 12, 2019 10:05 pm
Forum: Properties of Light
Topic: Question on 1A 11
Replies: 4
Views: 27

Re: Question on 1A 11

The Balmer and Lyman series are series defined by the final position of the electron, after a photon is emitted. The Lyman series involve jumps to or from the ground state (n=1); the Balmer series (in which all the lines are in the visible region) corresponds to n=2.
by 805422680
Sat Oct 12, 2019 10:02 pm
Forum: Photoelectric Effect
Topic: Removing electrons in Photoelectric concept
Replies: 2
Views: 16

Re: Removing electrons in Photoelectric concept

The threshold energy required to remove an electron from the metal surface varies from metal to metal. Each metal has a different threshold energy. To remove an electron from the metal surface, the energy of the photon hitting the metal surface has to be exactly equal to the difference of energy bet...
by 805422680
Wed Oct 02, 2019 10:08 pm
Forum: Significant Figures
Topic: When to apply sig figs?
Replies: 4
Views: 47

Re: When to apply sig figs?

No; you should only round your answer to the proper amount of significant figures at the end of the problem. You should never round off your intermediary calculations.
by 805422680
Wed Oct 02, 2019 10:02 pm
Forum: Empirical & Molecular Formulas
Topic: 5 Homework Problems Due
Replies: 21
Views: 220

Re: 5 Homework Problems Due

You only have to do five problems out of the ones that Professor Lavelle selected, but my TA said it is highly beneficial to do most or even all the selected problems. I think about 1/8 problems on the tests are based off of the concepts from the homework.
by 805422680
Wed Oct 02, 2019 9:58 pm
Forum: SI Units, Unit Conversions
Topic: Sig figs
Replies: 18
Views: 188

Re: Sig figs

Sig figs should be designated individually for each problem. It's the least accurate out of all the numbers given. Also, make sure you don't round off digits when you're calculating. Only round off with sig figs at the end.
by 805422680
Wed Oct 02, 2019 9:57 pm
Forum: SI Units, Unit Conversions
Topic: Next Week's Test
Replies: 8
Views: 124

Re: Next Week's Test

I think the test is just fundamentals, or what prof Lavelle says is 'review of high school chemistry.' I think as long as you go over the material that we've covered up to now, you should be fine.
by 805422680
Wed Oct 02, 2019 9:55 pm
Forum: Significant Figures
Topic: Powers of 10
Replies: 10
Views: 95

Re: Powers of 10

Using powers of ten is really up to your discretion. If you have 104859 grams, you may want to change that into kilograms (104.859 kg). If you have a really small number of grams, for example, .00456 grams, you would probably want to convert that to 4.56 mg.

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