## Search found 101 matches

Sat Mar 14, 2020 5:41 pm
Forum: Ideal Gases
Topic: Kc
Replies: 7
Views: 101

### Re: Kc

You may only use aqueous or gas molecules since they have concentrations.
Sat Mar 14, 2020 5:40 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Gibbs free energy
Replies: 9
Views: 146

### Re: Gibbs free energy

G is not at standard state G* is at standard conditions.
Sat Mar 14, 2020 5:39 pm
Forum: Zero Order Reactions
Topic: units of k
Replies: 5
Views: 96

### Re: units of k

There are different units of k due to the powers involved in concentrations. Units could be more than the power of 1 which would change the unit of k.
Sat Mar 14, 2020 5:37 pm
Forum: Acidity & Basicity Constants and The Conjugate Seesaw
Topic: Ka and Kb
Replies: 4
Views: 172

### Re: Ka and Kb

Correct, Ka is based on H+ concentration, Kb is based on OH- concentration. You can use these values to determine pH and pOH respectively given the formula.
Sat Mar 14, 2020 5:35 pm
Forum: General Science Questions
Topic: Final Overview
Replies: 5
Views: 132

### Re: Final Overview

I would prioritize Kinetics and also Thermodynamics. The other concepts should all be included, although Kinetics would be could be a main topic.
Sun Mar 08, 2020 9:19 pm
Forum: Van't Hoff Equation
Topic: Van't Hoff Equation
Replies: 6
Views: 102

### Re: Van't Hoff Equation

You can derive this equation when solving for different temperature phases or k's. Mainly, we would try to find k2/k1.
Sun Mar 08, 2020 9:17 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Cell Diagram
Replies: 16
Views: 205

### Re: Cell Diagram

Anode should be on the left, cathode should be on the right in most diagrams.
Sun Mar 08, 2020 9:16 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Exothermic vs. Endothermic
Replies: 14
Views: 120

### Re: Exothermic vs. Endothermic

If activation energy is higher than products, exothermic. If higher than reactants, endothermic.
Sun Mar 08, 2020 9:15 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: Figuring out n
Replies: 15
Views: 198

### Re: Figuring out n

n is determined by the amount of electrons transferred in the reactions, easier to find in half-reactions.
Sun Mar 08, 2020 9:13 pm
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: calculating Q
Replies: 12
Views: 104

### Re: calculating Q

Q should be anode/cathode.
Sun Mar 01, 2020 9:12 pm
Forum: Method of Initial Rates (To Determine n and k)
Topic: first order
Replies: 8
Views: 121

### Re: first order

Graph is linear and slope is usually negative.
Sun Mar 01, 2020 9:11 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Work
Replies: 14
Views: 282

### Re: Work

Work done on system is positive, work done by the system is negative.
Sun Mar 01, 2020 9:08 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: delta G=-nFE
Replies: 7
Views: 118

### Re: delta G=-nFE

You can calculate n whether by the other information given, such as Gibbs Free Energy, or using the half reactions to determine the amount of electrons.
Sun Mar 01, 2020 9:00 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: when to use K or Q
Replies: 18
Views: 236

### Re: when to use K or Q

Use K when reactions are at equilibrium, Q when they are not. Q determines which side of the reaction is favored.
Sun Mar 01, 2020 8:58 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Kelvin or Celsius?
Replies: 47
Views: 985

### Re: Kelvin or Celsius?

Kelvin because the ideal gas constant is in terms of Kelvin not celsius.
Sat Feb 22, 2020 2:09 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Replies: 20
Views: 299

Adding an inert gas increases the pressure of the system but in terms of equilibrium it has no effect. Only temperature can do that as it forces the reaction to favor one side or the other.
Sat Feb 22, 2020 2:08 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic Cells
Replies: 8
Views: 52

### Re: Galvanic Cells

Galvanic cells are cells that converts chemical energy into electrical energy.
Sat Feb 22, 2020 2:05 pm
Forum: Balancing Redox Reactions
Topic: Redox in Acid/ Basic Solutions
Replies: 8
Views: 89

### Re: Redox in Acid/ Basic Solutions

Redox in both acidic and basic solutions are very similar. It comes down to adding the H+ or OH- to acidic and basic equations respectively to determine what is being oxidized and reduced.
Sat Feb 22, 2020 2:02 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: converting T to kelvin
Replies: 21
Views: 328

### Re: converting T to kelvin

T to kelvin should only be applied when the the problem involves using constants or equations that use Kelvin instead of Temperature. In ideal gas law equations, you would use Kelvin (+273.15) if given celcsius.
Sat Feb 22, 2020 2:00 pm
Forum: Phase Changes & Related Calculations
Topic: delta G0 versus delta G
Replies: 15
Views: 361

### Re: delta G0 versus delta G

Delta G will always be in the conditions given in the problem where as Delta G naught is in standard conditions.
Fri Feb 14, 2020 2:21 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Constant Pressure and Volume
Replies: 6
Views: 123

### Re: Constant Pressure and Volume

Cp=DeltaH/Delta T and Cv=DeltaU/Delta T. Calculations can also vary depending on if the atom is monoatomic, linear, etc this is when dealing with Cv,m and Cp,m.
Fri Feb 14, 2020 2:19 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy equation
Replies: 3
Views: 54

### Re: Entropy equation

You can use this when dealing with an isothermal process and also when dealing with phase changes.
Fri Feb 14, 2020 2:17 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs Irreversible
Replies: 13
Views: 248

### Re: Reversible vs Irreversible

Reversible is when the reaction is at equilibrium where as irreversible is not, an example of this would be combustion. Equations that relate to this would be work in which reversible process would be:-nRTlnV2/V1 and irreversible: -Pex*DeltaV
Fri Feb 14, 2020 2:14 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: K and Q and G
Replies: 6
Views: 106

### Re: K and Q and G

Q refers to when the reaction given is not at an equilibrium where as K would mean the reaction is at equilibrium. Usually, Q can = K such that delta g would be 0 and delta g naught would be -RT ln K at equilibrium.
Fri Feb 14, 2020 2:11 pm
Forum: Phase Changes & Related Calculations
Topic: Equation Choice
Replies: 5
Views: 196

### Re: Equation Choice

Phase change occurs when a molecule/reaction goes from solid to liquid, liquid to gas, etc. This denotes fusion, vaporization, in terms of change in enthalpy. We learned equations: Hvap=Hvap-Hliq and Hfus=Hliq-Hsol and Hsub=Hvap-Hsol which relate to phase changes.
Sun Feb 09, 2020 9:59 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Hess's Law
Replies: 10
Views: 78

### Re: Hess's Law

Since it is a state function, enthalpy values can be added together or subtracted.
Sun Feb 09, 2020 9:56 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE BOX Reverse ?
Replies: 4
Views: 96

### Re: ICE BOX Reverse ?

The problem should always allow you to find the concentration. If given a change in concentration you can use that to solve for the initial.
Sun Feb 09, 2020 9:54 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE BOX
Replies: 27
Views: 253

### Re: ICE BOX

If the number (x) is less than 10^-3
Sun Feb 09, 2020 9:53 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: equations
Replies: 4
Views: 53

### Re: equations

It usually depends on a lot of factors. If the problem were to give temperature change or volume change nCln (T2/T1) or -nRT ln (V2/V1) respectively. Those are usually the equations you would need to use when there is a change in some constant. Otherwise just know the equations that have work exclus...
Sun Feb 09, 2020 9:50 pm
Forum: Calculating Work of Expansion
Topic: Ideal Gas Internal Energy
Replies: 4
Views: 38

### Re: Ideal Gas Internal Energy

This value usually denotes Cv or Cp. The number depends on if the molecule is monoatomic, diatomic, etc.
Sun Feb 02, 2020 2:00 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated System
Replies: 4
Views: 33

### Re: Isolated System

Isolated systems cannot exchange heat or work for that reason delta u will be 0. (0+0=0)
Sun Feb 02, 2020 1:59 pm
Forum: Calculating Work of Expansion
Topic: Gas constant
Replies: 5
Views: 40

### Re: Gas constant

Gas constant values are dependent on the unit of pressure. Since atm is given, you would use the constant with atm as the units present.
Sun Feb 02, 2020 1:57 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Definition of First Law
Replies: 9
Views: 78

### Re: Definition of First Law

Conservation of energy, a function of heat and work. Delta U= q+w.
Sun Feb 02, 2020 1:53 pm
Forum: Ideal Gases
Topic: pv=nrt
Replies: 9
Views: 115

### Re: pv=nrt

Pressure, volume, moles, and temperature can all vary as R is is the Ideal gas law constant. Usually, there are relationships such as when volume increases, pressure decreases, while temperature and moles carry a similar relationship.
Sun Feb 02, 2020 1:50 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy units
Replies: 4
Views: 31

### Re: Entropy units

Answer should be based on the units given in the problem. Joules can be represented in many units kJ, kg.m^2, s^-2, etc. Just identify what the question asks and have consistent units.
Sun Jan 26, 2020 10:59 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changing K
Replies: 13
Views: 113

### Re: Changing K

Only increasing or decreasing temperature can change the value of K.
Sun Jan 26, 2020 10:57 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Gas Constant
Replies: 13
Views: 82

### Re: Gas Constant

The Gas Constant value is determined based on the pressure usually and other components in the ideal gas law equation. Pressure can be measured in atm, bar, etc, and R is represented in many of those units.
Sun Jan 26, 2020 10:55 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Pure solids & liquids
Replies: 5
Views: 57

### Re: Pure solids & liquids

Pure solids and liquids are not included in solving for K. They also cannot dissolve or be used in ICE tables.
Sun Jan 26, 2020 10:52 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kp to Kc
Replies: 11
Views: 83

### Re: Kp to Kc

Yes as long as it is in the form of a gas. Any gas or aqueous reactant or product can be included in solving for K.
Sun Jan 26, 2020 8:32 pm
Forum: Ideal Gases
Topic: R Constant
Replies: 18
Views: 251

### Re: R Constant

R constants are given and should be applied based on the units given in the problem. Pressure is the unit to look for as it determines which R constant to plug ig to PV = nRT
Sun Jan 26, 2020 8:30 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Shifts Left or Right
Replies: 15
Views: 171

### Re: Reaction Shifts Left or Right

In an exothermic reaction, the reaction will shift to the left when temperature is increased due to heat already being on the product and needing heat on the reactant side since the reverse reaction is endothermic.
Sun Jan 19, 2020 6:20 pm
Forum: Ideal Gases
Topic: 5I.15
Replies: 5
Views: 128

### Re: 5I.15

ICE tables only involve finding the concencentration using only aqueous or gas molecules. Solids or liquids are not included. You also use ICE tables when you are given intial concentrations.
Sun Jan 19, 2020 5:16 pm
Forum: Ideal Gases
Topic: concentration
Replies: 5
Views: 42

### Re: concentration

You can derive the concentration using the ideal gas law. PV=nRT (n/V = P/RT) where n/V gives the concentration.
Sun Jan 19, 2020 5:14 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: ICE table
Replies: 11
Views: 68

### Re: ICE table

An ICE table should be used when given a weak base/acid. When finding concentration always take note of the 5% rule.
Sun Jan 19, 2020 4:40 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Shifts Left or Right
Replies: 15
Views: 171

### Re: Reaction Shifts Left or Right

In this reaction, heat is on the product side. This indicates that the reverse reaction is endothermic. In this case, an increase in temperature would favor the reactants, caushing a shift to the left.
Sun Jan 19, 2020 4:32 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc from K
Replies: 3
Views: 31

### Re: Kc from K

K usually represents Kc or Kp. Kc deals with the concentrations of a reaction whereas Kp deals with partial pressures. I think we would just evaluate the reaction with how we normally calculate for K.
Sun Jan 12, 2020 2:13 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE vs Normal Concentrations
Replies: 5
Views: 36

### Re: ICE vs Normal Concentrations

ICE is used when we are given intial concentrations and we can use gasses from the product and reactant side to solve for x (final concentration).
Sun Jan 12, 2020 1:54 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: 5H.1
Replies: 2
Views: 23

### Re: 5H.1

For this problem, you would follow the procedure we've been doing K=[P]/[R]. If other temperatures were given, then there would be different K values so just be aware of that. For this problem, the products and reactants are all gasses and so all the concentrations of P and R would be present in the...
Sun Jan 12, 2020 1:48 pm
Forum: Ideal Gases
Topic: Bars vs atmospheres
Replies: 13
Views: 90

### Re: Bars vs atmospheres

Both can be used for measuring pressure, depending on the context of the problem it would be good to stay consistent with the units.
Sun Jan 12, 2020 1:38 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Temperature and K
Replies: 6
Views: 75

### Re: Temperature and K

Temperature is the only factor than can affect the value of K. Usually when K is given at 2 different temperatures, it is likely that those values would be different due to a difference in energy.
Sun Jan 12, 2020 1:17 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: when to use Kc vs Kp
Replies: 11
Views: 77

### Re: when to use Kc vs Kp

Kc usually deals with molar concentration and the activity of chemical reactions. Kp deals with partial pressure only when the products and reactants are forms of gasses.
Wed Dec 04, 2019 9:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs linear
Replies: 56
Views: 1161

### Re: Bent vs linear

A molecule would be linear if there is one central atom and no lone pairs on the central atom where as the molecule would be bent if there is a lone pair. The only exception is AX2E3 where it is also linear.
Wed Dec 04, 2019 9:36 pm
Forum: Lewis Acids & Bases
Topic: HCl and HI
Replies: 10
Views: 112

### Re: HCl and HI

HI is more stronger because chlorine is more electronegative and will have a stronger bond. The weaker the bond the stronger the acid.
Wed Dec 04, 2019 9:28 pm
Forum: Amphoteric Compounds
Topic: H2O
Replies: 8
Views: 53

### Re: H2O

H20 can be both since it can accept/give protons and it can also be amphoteric.
Wed Dec 04, 2019 9:24 pm
Forum: Polyprotic Acids & Bases
Topic: Ka value
Replies: 5
Views: 92

### Re: Ka value

Ka values will decrease the more negatively charged the ion becomes. The H+ ion would be harder to lose thus Ka1 would be the greatest.
Wed Dec 04, 2019 9:19 pm
Forum: Lewis Acids & Bases
Topic: Lewis and Bronsted
Replies: 3
Views: 41

### Re: Lewis and Bronsted

Bronsted bases and acids deal with protons (H+) where bases accept protons while acids give them off. Vice versa with Lewis bases and acids except it would be electrons instead of protons.
Mon Nov 25, 2019 7:46 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular shape of carbon Dioxide
Replies: 10
Views: 100

### Re: Molecular shape of carbon Dioxide

CO2 would have a molecular shape of Linear since it follows the AX2 model which corresponds to a bond angle of 180 degrees.
Mon Nov 25, 2019 7:43 am
Forum: Octet Exceptions
Topic: expanded octet
Replies: 7
Views: 251

### Re: expanded octet

Elements that can have expanded octets include the 3rd row and every element below. This is due to the d-block with some elements as an exception to this rule. Elements above the third row must fulfill the octet rule when drawing a lewis structure.
Mon Nov 25, 2019 7:40 am
Forum: Dipole Moments
Topic: Melting points
Replies: 15
Views: 394

### Re: Melting points

Melting point has a direct relationship with intermolecular forces. If the strength of a intermolecular force is strong, then the melting point must be high and vice versa with a weaker IMF. For example, molecules that have dispersion would have a lower melting point than for example a hydrogen bond...
Mon Nov 25, 2019 7:38 am
Forum: Sigma & Pi Bonds
Topic: Molecular Shape
Replies: 11
Views: 127

### Re: Molecular Shape

Sigma and pi bonds do not really affect molecular shape due to bonds (single, double, or triple) being considered as only one region of electron density.
Mon Nov 25, 2019 7:35 am
Forum: Bond Lengths & Energies
Topic: Hydrogen Bonding and Dispersion
Replies: 5
Views: 163

### Re: Hydrogen Bonding and Dispersion

Hydrogen bonding occurs when hydrogen is bonded to Nitrogen, Oxygen, or Fluorine. Dispersion occurs when two non polar molecules interact. Also dispersion is the most weakest intermolecular force, while hydrogen bonding is one of the strongest.
Mon Nov 25, 2019 7:33 am
Forum: Coordinate Covalent Bonds
Topic: Covalent character: BeCl2 Vs MgCl2
Replies: 4
Views: 1313

### Re: Covalent character: BeCl2 Vs MgCl2

BeCl2 has more covalent character due to the fact that the electronegativity difference is smaller than MgCl2.
Mon Nov 25, 2019 7:31 am
Forum: Coordinate Covalent Bonds
Topic: carbon monoxide formal charges
Replies: 4
Views: 169

### Re: carbon monoxide formal charges

This is due to the lewis structure as carbon monoxide requires a triple bond to fulfill the 10 valence electrons needed in the structure. Furthermore when conducting formal charge, carbon would have a +1 charge while oxygen would have a -1 charge.
Mon Nov 25, 2019 7:29 am
Forum: Properties of Light
Topic: Frequency vs. Velocity
Replies: 8
Views: 252

### Re: Frequency vs. Velocity

Frequency and velocity are not the same thing as frequency is obtained by dividing the speed of light over a give wavelength where as velocity is always a constant as "c" which is the speed of light.
Mon Nov 25, 2019 7:25 am
Forum: Sigma & Pi Bonds
Topic: sigma and pi bonds
Replies: 19
Views: 446

### Re: sigma and pi bonds

Single bonds will always be a sigma bond. Double bonds will always have one pi and one sigma bond. Lastly, triple bonds will always have 2 pi bonds and one sigma bond.
Mon Nov 25, 2019 7:24 am
Forum: Coordinate Covalent Bonds
Topic: Electronegativity
Replies: 12
Views: 941

### Re: Electronegativity

Electronegativity increases as you go up and to the right of the periodic table thus why Fluorine has the highest electronegativity. Based on electron affinity and ionization energy trends this also correlates with higher electronegativity.
Sun Nov 17, 2019 3:23 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Repulsion
Replies: 6
Views: 63

### Repulsion

How do you determine repulsion strength and finding the least amount of repulsion when given a structure?
Sun Nov 17, 2019 3:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 2
Views: 31

### Bond Angles

How would you determine the angle of a bond and know that it should be lower than a specific type of angle bond? For example, if a molecule is trigonal planar, we would need to know that the bond angles would be exactly 120 degrees?
Sun Nov 17, 2019 2:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Distortion
Replies: 2
Views: 40

### Distortion

What does the term "distort" refer to when talking about naming molecules and angles?
Sun Nov 17, 2019 2:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Model
Replies: 5
Views: 39

### Re: VSEPR Model

Electron arrangement refers to the placement of electrons, while the molecular shape would determine the bound atoms of a molecule and show the actual regions of electron density, allowing us to determine the name of the shape of the molecule.
Sun Nov 17, 2019 2:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Electron Density
Replies: 2
Views: 31

### Re: Electron Density

Since an electron is present, this represents a region of electron density. If it were a bond or lone pair or just a single electron present, as long as there is one electron, it is a region.
Fri Nov 08, 2019 11:53 am
Forum: DeBroglie Equation
Topic: De Broglie Equation Derivation and Use
Replies: 7
Views: 268

### Re: De Broglie Equation Derivation and Use

De Broglie Equation is used to find the wavelength of a particle with momentum, usually dealing with an electron. The equation is wavelength (lambda)=h/p where p can be rewritten as mass * velocity, while h represents Planck's constant.
Fri Nov 08, 2019 11:48 am
Forum: DeBroglie Equation
Topic: Light waves
Replies: 2
Views: 108

### Re: Light waves

You only use De Broglie when dealing with a particle with momentum, typically having mass and velocity. When solving for light waves, you would use E=Hv, and c=wavelength*v
Fri Nov 08, 2019 11:46 am
Forum: Photoelectric Effect
Topic: frequency and ejection of electrons
Replies: 7
Views: 241

### Re: frequency and ejection of electrons

Based on the photoelectric effect, the ejection of electrons are determined by the frequency. If the light source has a short wavelength then it can eject electrons since the frequency would be high.
Fri Nov 08, 2019 11:42 am
Forum: Formal Charge and Oxidation Numbers
Topic: central atom
Replies: 21
Views: 249

### Re: central atom

The central atom should be the most electronegative and while creating Lewis Structures, you want the formal charge to be as close to 0 as possible. You may need to change/add bonds such as by adding double bonds to fulfill that formal charge, it just depends on the compound given.
Fri Nov 08, 2019 11:41 am
Forum: Lewis Structures
Topic: Exceptions to Octet Rule
Replies: 7
Views: 88

### Re: Exceptions to Octet Rule

Elements in the third period can have more than 8 electrons and are the only exceptions to the octet rule. For example, Cl would be an exception.
Sun Nov 03, 2019 6:57 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge and Energy
Replies: 4
Views: 57

### Re: Formal Charge and Energy

Formal charge shows us which atom has the highest energy due to it indicating if electrons were gained or lost during the bond. Based on the charge, we would determine which Lewis Structure would be best based on having the lowest formal charges.
Sun Nov 03, 2019 6:38 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic vs Covalent
Replies: 14
Views: 211

### Re: Ionic vs Covalent

You can tell if a bond is ionic or covalent based on the atoms present. Ionic bonds are bonds between a metal and nonmetal whereas covalent bonds are bonds between two nonmetals. Knowing this, you can determine whether a bond is ionic or covalent.
Sun Nov 03, 2019 6:35 pm
Forum: DeBroglie Equation
Replies: 7
Views: 103

When mass is given, use De Broglie hence the "m" in the equation and not on the other light equations. Also the light equations given, usually relate to photons where as De Broglie relates to electrons.
Sun Nov 03, 2019 6:19 pm
Forum: Lewis Structures
Topic: Steps to Drawing a Lewis Structure
Replies: 6
Views: 61

### Re: Steps to Drawing a Lewis Structure

First, count the amount of valence electrons. Second, determine what atom is most electronegative, this will be the central atom. Next, fill in bonds and dots based on the amount of electrons and the octet rule. Next, calculate the formal charges and keep manipulating bonds until you get the lowest ...
Sun Nov 03, 2019 5:59 pm
Forum: Molarity, Solutions, Dilutions
Topic: Dilution Equation
Replies: 4
Views: 166

### Re: Dilution Equation

It just depends on the question and the units given. If V2/V1 was given in mL, and you were to find the other volume using the dilution equation, you would to have your final answer be in mL as well.
Sun Oct 27, 2019 5:41 pm
Forum: Lewis Structures
Topic: 2C15
Replies: 1
Views: 65

### 2C15

Two contributions to the resonance structure are shown below for each species. Determine the formal charge on each atom and then, if possible, identify the Lewis structure of lower energy for each species. a) Shows two structures of (HS03)^- one with a double bond one without no double bond. b) Show...
Sun Oct 27, 2019 5:28 pm
Forum: Ionic & Covalent Bonds
Topic: Double bond placement
Replies: 15
Views: 181

### Re: Double bond placement

In most cases, double bond placement does not really matter as long as you fulfill the amount of electrons required to represent the molecule and that you follow the octet rule. If you see Hydrogen, Oxygen, Nitrogen, or Carbon, just note that Hydrogen prefers 1 bond, Oxygen (2), Nitrogen (3), and Ca...
Sun Oct 27, 2019 5:22 pm
Forum: Lewis Structures
Topic: Creating Lewis Structures
Replies: 7
Views: 100

### Creating Lewis Structures

If we were to be given a compound such as ONF, how would we know which atom would be in the middle of the structure?
Sun Oct 27, 2019 5:20 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions to Electron Configuration
Replies: 7
Views: 91

### Re: Exceptions to Electron Configuration

Furthermore to Copper and Chromium being the only exceptions, half full/ full d sub-shells have lower energy thus they are more stable. With Cr and Cu having 1 electron on the 4s sub-shell that electron would be willing to be moved to the d sub shell to fulfill that stability.
Sat Oct 26, 2019 11:39 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic and Covalent Bonds
Replies: 5
Views: 75

### Re: Ionic and Covalent Bonds

Ionic Bonds is when an ion with a positive charge bonds with an ion with a negative charge. This is when a metal typically bonds with a non metal. On the other hand, Covalent Bonds is when two nonmetals form a bond through the sharing of electrons.
Sun Oct 20, 2019 5:15 pm
Forum: DeBroglie Equation
Topic: DeBroglie Equation
Replies: 11
Views: 150

### Re: DeBroglie Equation

DeBroglie Equation is used to calculate DeBroglie Wavelength. You use this when given given that a particle has momentum and are trying to find the wavelength. To find this number you must use Planck's constant and divide that by the mass and velocity of the particle. Since we are calculating wavele...
Sun Oct 20, 2019 4:59 pm
Forum: Photoelectric Effect
Topic: 1B19
Replies: 3
Views: 89

### 1B19

Protons and neutrons have nearly the same mass. How different are their wavelengths? Calculate the wavelength of each particle when traveling at 2.75 * 10^5 m*s^-1 in a particle accelerator and report the difference as a percentage of the wavelength of the neutron. I am confused on how to calculate ...
Sun Oct 20, 2019 4:25 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Hund's rule and Pauli Exclusion Principle
Replies: 14
Views: 224

### Re: Hund's rule and Pauli Exclusion Principle

Hund's Rule and Pauli Exclusion Principle share a relationship in which both relate to the building-up principle. Hund's Rule states that electrons in same subshell disperse through different orbitals with the same spins (parallel), where as Pauli Exclusion Principle allows a maximum of two electron...
Sun Oct 20, 2019 3:03 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Frequencies
Replies: 7
Views: 185

### Re: Frequencies

It would be beneficial if you at least had a general understanding of the electromagnetic spectrum, particular visible light (400-700 nm). There was a question on the textbook, (1A5) I believe where it asks to put some of the radiation in the order of increasing energy, so that may be something to n...
Sun Oct 20, 2019 2:34 pm
Forum: DeBroglie Equation
Topic: Wavelike properties of protons
Replies: 2
Views: 51

### Re: Wavelike properties of protons

Yes, protons, neutrons, and electrons all have wavelike properties. Based on De Broglie's Equation, any moving particle with moment has wavelike properties, thus neutrons and protons would fit this property.
Sun Oct 13, 2019 6:52 pm
Forum: Molarity, Solutions, Dilutions
Topic: M1V1=M2V2
Replies: 11
Views: 6803

### Re: M1V1=M2V2

You use M1V1=M2V2 in dilution problems, typically asking for either the concentration or volume in either the initial side or final side of the equation. One to thing to note is to look closely at what the question is asking for. Just because you are given 2 volume measurements and 1 concentration v...
Sun Oct 13, 2019 6:24 pm
Forum: SI Units, Unit Conversions
Topic: Unit conversion
Replies: 15
Views: 531

### Re: Unit conversion

To convert from angstrom to any other units you must first understand the scientific notation of each measurement. Knowing that information you should use dimensional analysis, in other words, you would be making conversions in which you are cancelling out terms to where the units you want are in th...
Sun Oct 13, 2019 5:49 pm
Forum: Significant Figures
Topic: Sig Figs at the Beginning or End
Replies: 14
Views: 421

### Re: Sig Figs at the Beginning or End

You want your answer to be as accurate as possible so definitely focus on significant figures at the end of your calculation. In most cases, you could get away with rounding Oxygen's atomic mass to 16 grams or Hydrogen to 1.01 grams, but essentially you want to keep those significant figures and rou...
Sun Oct 13, 2019 5:16 pm
Forum: DeBroglie Equation
Topic: Wave properties of electrons
Replies: 3
Views: 69

### Re: Wave properties of electrons

Based on quantum mechanics, all matter has wavelike properties, including neutrons. As long as there is no indication that the the velocity or mass of an object is 0, it can be inferred that a particle has wavelike properties. We are only able to identify this if a particle has a relative low mass w...
Sun Oct 13, 2019 4:58 pm
Forum: Properties of Light
Topic: Photoelectric vs. Atomic spectra
Replies: 4
Views: 51

### Re: Photoelectric vs. Atomic spectra

The difference between the photoelectric effect and atomic spectroscopy is that one focuses on the analysis of light being either emitted or absorbed by a substance (spectroscopy) where as the other focuses on the emission of electrons when light hits a substance, for example metal. In spectroscopy,...
Fri Oct 04, 2019 1:10 am
Forum: SI Units, Unit Conversions
Topic: scientific notation
Replies: 7
Views: 80

### Re: scientific notation

I would use scientific notation when you have an answer that is either very large or very small, involving a lot of zeros as place holders for instance. You want to make sure your answer looks simplified. For example, even Avogadro's constant number is in scientific notation since the number itself ...
Fri Oct 04, 2019 1:02 am
Forum: Molarity, Solutions, Dilutions
Topic: Converting Before or After?
Replies: 10
Views: 159

### Re: Converting Before or After?

You should always convert after you've completed all steps necessary. For example if it is asking for volume, evidently the answer should be in some form of liter measurement. In these types of cases, just pay attention to the units given and determine whether you would need it to be in milliliters,...
Fri Oct 04, 2019 12:46 am
Forum: Significant Figures
Topic: How would sig figs be used in a problem?
Replies: 7
Views: 70

### Re: How would sig figs be used in a problem?

Usually, you would need to identify the least amount of significant figures given in the problem. Your answer should reflect that number. One example, could be multiplying the values (17.2) and (2.9) after calculations you would get 49.88 but as you can see, (2.9) has 2 significant figures thus your...
Thu Oct 03, 2019 6:40 pm
Forum: Limiting Reactant Calculations
Topic: M19
Replies: 3
Views: 104

### M19

M19) A stimulant in coffee and tea is caffeine, a substance of molar mass 194 g*mol^-1. When 0.376 g of caffeine was burned, 0.682 g of carbon dioxide, 0.174 g of water, and 0.110 g of nitrogen were formed. Determine the empirical and molecular formulas of caffeine, and write the equation for its co...