## Search found 61 matches

Sun Mar 17, 2019 12:15 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Types of Molecularity
Replies: 4
Views: 895

### Re: Types of Molecularity

A reaction can be unimolecular with only one reactant molecule, bimolecular where two reactant molecules collide, and termolecular where three molecules must collide at the right orientation and with enough energy to cause a reaction. It is much more difficult for three molecules to collide perfectl...
Sun Mar 17, 2019 12:10 am
Forum: General Rate Laws
Topic: Exergonic reaction
Replies: 3
Views: 315

### Re: Exergonic reaction

AN exergonic reaction is one in which energy is released as the reaction proceeds forward.
Sun Mar 17, 2019 12:07 am
Forum: General Rate Laws
Topic: pseudo rate laws
Replies: 4
Views: 379

### Re: pseudo rate laws

A psuedo rate law is when a higher rate law is adjusted to essentially form a lower order rate law. This is done in order to see how a single reactant affects the rate and is done by increasing the concentration of one of the reactants so much that any change in it has no effect on the rate.
Wed Mar 06, 2019 11:19 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: n and m
Replies: 3
Views: 159

### Re: n and m

n and m are the variables used to represent the order of the individual reactants. Essentially, you could use any variables to represent the same thing but n and m are most commonly used. The overall order of the reaction is found by adding all of the orders of the individual reactants, so if there ...
Wed Mar 06, 2019 11:14 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Units
Replies: 6
Views: 235

### Re: Units

Like the previous comment said, the rate is in mol*L^-1*s^-1 or M*s-1. The units of the rate constant changes with the order of the overall reaction to ensure that the rate always ends up with the units previously mentioned.
Wed Mar 06, 2019 10:23 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Order of a Reaction
Replies: 1
Views: 133

### Re: Order of a Reaction

You can only determine the order and then the rate law through experimental data. So, you would have to calculate the order for each individual reactant using the experimental data then obtain the order of the overall reaction from that.
Thu Feb 28, 2019 4:00 am
Forum: Balancing Redox Reactions
Topic: Knowing which atom was oxidized/ reduced
Replies: 3
Views: 148

### Re: Knowing which atom was oxidized/ reduced

The charges that you are referring to are actually the oxidation numbers of the elements so even if it is not explicitly written, all elements in the reaction have an oxidation number. You can find the oxidation numbers by calculating the numbers of the elements you know then by adding and subtracti...
Thu Feb 28, 2019 3:49 am
Forum: Balancing Redox Reactions
Topic: Oxidation Numbers
Replies: 3
Views: 172

### Re: Oxidation Numbers

The oxidation numbers will be zero for elements in their natural state. O2 and Cl2 are found naturally as diatomic gas molecules so when in that form, they will have an oxidation state of zero. If metals like Zn are in their natural solid state, then they will also have an oxidation number of zero.
Thu Feb 28, 2019 3:46 am
Forum: Balancing Redox Reactions
Topic: Acidic Solutions
Replies: 7
Views: 321

### Re: Acidic Solutions

You first use H2O to balance the oxygens so you put the H2O on the side opposite of the molecule that includes oxygen. Then you use H+ to balance the hydrogens so you will likely put the H+ on the side opposite of the H2O. I think there might be a couple exceptions to this, but usually this is how i...
Tue Feb 19, 2019 10:25 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 3
Views: 346

### Re: Spontaneity

Delta S total is the sum of delta S of the system and delta S of the surroundings. According to the second law of thermodynamics, a spontaneous change is accompanied by an increase in the total entropy of the system and its surroundings. Therefore, if there is an increase in the entropy of the syste...
Tue Feb 19, 2019 10:17 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Indications
Replies: 3
Views: 121

### Re: Indications

If a reaction is spontaneous, then delta G is negative. A very negative change in enthalpy (exothermic reaction) will likely cause delta G to be negative. A very positive change in entropy would likely also make delta G negative. Like the previous comment said, the opposite would then make delta G m...
Tue Feb 19, 2019 10:10 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: difference between gibbs and entropy
Replies: 3
Views: 117

### Re: difference between gibbs and entropy

Gibbs free energy is the energy in the system that is free to do work. Entropy is the amount of disorder in the system. The change in free energy is affected by the change in entropy and the change in enthalpy.
Thu Feb 14, 2019 3:36 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Calorimeter - Type of System
Replies: 5
Views: 500

### Re: Calorimeter - Type of System

Calorimeters are isolated systems because they are used to determine the heat capacities of substances, so no heat can be lost. Therefore, in calorimeters, it would be implied that the change in internal energy is equal to work since the change in heat is zero.
Thu Feb 14, 2019 3:20 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Cp,m
Replies: 5
Views: 418

### Re: Cp,m

You use these terms for an ideal gas. The Cp,m is used at constant pressure and the Cv,m is used at constant volume. The m indicates that it is the molar heat capacity so you would multiply it by the amount of moles in order to get the heat capacity.
Thu Feb 14, 2019 3:05 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Expansion of a system
Replies: 8
Views: 514

### Re: Expansion of a system

A system is expanding if the system is doing work. You can tell that it is expanding if w is negative because this means the system is losing energy through doing work.
Wed Feb 06, 2019 7:47 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Internal energy
Replies: 5
Views: 202

### Re: Internal energy

Internal energy is the energy within the system and is calculated by adding q and w together. It can't be calculated at a single point in time, but the change in internal energy can be calculated. At constant pressure, the change in internal energy is equal to the enthalpy minus pressure times chang...
Wed Feb 06, 2019 7:43 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Heat capacity
Replies: 2
Views: 116

### Re: Heat capacity

I think heat capacity is often given. If anything, we may have to know how to calculate specific or molar heat capacity after being given the heat capacity and the amount of substance.
Wed Feb 06, 2019 7:42 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: thermo equation explanation
Replies: 4
Views: 201

### Re: thermo equation explanation

These equations both calculate the entropy, or disorder, of the system. There are lots of equations to calculate entropy depending on the conditions of the system. The first equation is used for a reversible, isothermal process when the heat and temperature is given. Therefore, this is the equation ...
Thu Jan 31, 2019 3:25 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: bond enthalpies
Replies: 5
Views: 208

### Re: bond enthalpies

The enthalpies of bonds always begin as positive values. The sign will only change depending on whether the bond is being broken or formed. The formula for calculating bond enthalpies is bonds broken - bonds formed because breaking bonds requires adding energy and is an endothermic process (positive...
Thu Jan 31, 2019 3:19 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: steam vs. water
Replies: 5
Views: 285

### Re: steam vs. water

The reason why steam causes worse burns than water is more easily understood while looking at the heating curve of water. Even if steam and liquid water are both at 100 degrees celsius, the steam contains more Jules of heat energy than liquid water. This is because it includes all the heat energy re...
Thu Jan 31, 2019 3:10 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Extensive vs. Intensive
Replies: 5
Views: 451

### Re: Extensive vs. Intensive

Extensive properties are reliant upon the amount of substance present. For example, mass is an extensive property. Intensive properties are not reliant upon the amount of substance that is present and is intrinsic to the substance. General heat capacity is extensive because it is not divided by the ...
Sun Jan 27, 2019 9:43 pm
Forum: Phase Changes & Related Calculations
Topic: state properties
Replies: 3
Views: 175

### Re: state properties

State properties only rely on the values of the initial and final state. Other properties such as heat and work are not state properties because they do not measure "states" but they measure the energy required over a process, if that makes sense. For these type of properties, how the fina...
Sun Jan 27, 2019 9:37 pm
Forum: Phase Changes & Related Calculations
Topic: Steam v. Boiling Water
Replies: 4
Views: 138

### Re: Steam v. Boiling Water

If you look at a water heat capacity chart, the Jules of energy being added to liquid water after it reaches 100 degrees celsius is used to break the bonds of the molecules of liquid water and vaporize the water instead of being used to heat up the liquid water. Therefore, the steam contains more Ju...
Sun Jan 27, 2019 8:40 pm
Forum: Phase Changes & Related Calculations
Topic: State Properties
Replies: 5
Views: 170

### Re: State Properties

State functions only depend on the initial and final state, not how the final state was obtained. Heat and work on the other hand, do not describe states but the amount of energy taken in or exerted during a process.
Wed Jan 16, 2019 12:23 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Acids
Replies: 6
Views: 207

### Re: Acids

A weak acid does not fully dissociate in water and therefore, would require an equilibrium equation. A strong acid fully dissociates in water and so it would be written as just a forward reaction. You just have to memorize the strong acids and every other acid is a weak acid. The strong acids are HC...
Wed Jan 16, 2019 11:48 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Converting Between Kp and Kc
Replies: 3
Views: 108

### Re: Converting Between Kp and Kc

Going off of the previous comment, they are both K constants and calculated the same way. Kp is used for gases and Kc is used for aqueous solutions and concentrations. When doing Kp, you use partial pressures of gases. If you are given the concentration of the gases instead of the partial pressures,...
Wed Jan 16, 2019 11:45 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Test 1 topics
Replies: 1
Views: 45

### Re: Test 1 topics

Yes, as far as I know, I believe that we will only be tested on the first 2 outlines.
Wed Jan 09, 2019 9:32 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Lecture Example of Calculating the equilibrium composition
Replies: 2
Views: 99

### Re: Lecture Example of Calculating the equilibrium composition

You would add the 8.434x10^-3 on the ADP side because it is a product and you would subtract this number on the ATP side because it is a reactant. The basic idea of a reaction is that the reactants are undergoing a chemical change and forming the products. You use the same number for both ADP and AT...
Wed Jan 09, 2019 9:11 pm
Forum: Ideal Gases
Topic: Units
Replies: 19
Views: 410

### Re: Units

Yes, you would put temperature in Kelvin. Usually when doing calculations, Kelvin is the unit that should be used.
Wed Jan 09, 2019 8:24 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Reaction Quotient
Replies: 5
Views: 244

### Re: Reaction Quotient

Going off of the previous comments, Q is the reaction quotient which is calculated the same way that K is. However, K is used once the reaction has reached equilibrium while Q is used for any other point in the reaction while it is reaching equilibrium.
Tue Dec 04, 2018 5:32 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: CO3 2-
Replies: 2
Views: 194

### Re: CO3 2-

For a ligand to be a polydentate, do the ligands have to bond to the same transition metal atom or can they bond to different ones? For example, using CO3^2- as an example, if the third oxygen were to bond to another central transition metal atom, would that be tridentate?
Tue Dec 04, 2018 5:29 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Why is water monodentate?
Replies: 2
Views: 162

### Re: Why is water monodentate?

Water is monodentate because the two lone pairs are on the same atom. There is no structural possibility that a bond could form between each lone pair and the same central transition metal because there would be too much electron repulsion between the bonds.
Tue Dec 04, 2018 5:27 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: polydentate
Replies: 2
Views: 96

### Re: polydentate

I understand that if a ligand is bonding in multiple places to a central transition metal that it is a polydentate, but if the structure is not already drawn, how would you know if the ligand has the potential to be a polydentate and bind in multiple places?
Tue Nov 27, 2018 2:53 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent shape
Replies: 1
Views: 111

### Re: Bent shape

Yes, the bent shape is also sometimes called angular. Also, a molecule with two bonds and a single lone pair is still considered bent. The difference between a bent molecule with one lone pair vs two lone pairs would be the bond angle. A bent molecule with two lone pairs would have a smaller bond an...
Tue Nov 27, 2018 2:09 pm
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: pi bond
Replies: 4
Views: 188

### Re: pi bond

A molecule has a pi bond if there are any bonds that are double bonds or more within that molecule. A double bond consists of one sigma bond and one pi bond. A triple bond consists of one sigma bond and two pi bonds and so on. If a molecule with double bonds or triple bonds has a resonance structure...
Tue Nov 27, 2018 2:05 pm
Forum: Hybridization
Topic: hybridization
Replies: 3
Views: 204

### Re: hybridization

Going off of the previous responses, the 2 relates back to electronic configuration. The 2 describes which energy level the hybridization is occurring at. You could label it as 2sp, 2sp^2, etc. when hybridization occurs between the 2s and 2p orbitals, as is the case when hybridizing boron, carbon, n...
Mon Nov 26, 2018 8:44 pm
Forum: Administrative Questions and Class Announcements
Topic: Textbook
Replies: 3
Views: 168

### Textbook

Hi! I am in 14A and will be taking 14B next quarter. Does anybody know if we use the same textbook for 14B that we used for 14A?
Mon Nov 19, 2018 8:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Regions of electric density in VSEPR Model
Replies: 2
Views: 68

### Re: Regions of electric density in VSEPR Model

As you stated, they are one region of electron density because the electrons in a bond, whether it is single, double, or triple, are confined to the area between the two atoms. They are held in this area due to their attraction to the atoms' nuclei. I believe that this force of attraction probably o...
Mon Nov 19, 2018 7:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: multiple sigma bonds
Replies: 4
Views: 214

### Re: multiple sigma bonds

I believe that after the first bond, pi bonds begin to form. Like it was previously stated, double and triple bonds are formed by overlapping side by side p orbitals. These are pi bonds which can not rotate like sigma bonds can because they are side by side instead of end to end.
Mon Nov 19, 2018 7:41 pm
Forum: Hybridization
Topic: Relation to Bond Angles
Replies: 3
Views: 64

### Re: Relation to Bond Angles

I had similar confusion on this topic. Can someone please explain to me why the three h bonds without hybridization would be at 90 degree angles and how hybridization changes these angles to the correct bond angles according to VESPR?
Wed Nov 14, 2018 1:14 pm
Forum: Electronegativity
Topic: Electronegativity in Molecules with N,O,F
Replies: 4
Views: 338

### Re: Electronegativity in Molecules with N,O,F

NF3 would be able to create a hydrogen bond because H forms hydrogen bonds with N, O and F. The reasoning for this is because of the high electronegativity of these atoms and therefore, the large difference in electronegativities between hydrogen and these three atoms. It would be able to dissolve i...
Wed Nov 14, 2018 10:22 am
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Difference between polarizability and polarizing power.
Replies: 1
Views: 133

### Re: Difference between polarizability and polarizing power.

The ability of a cation to distort or polarize an anion is the cation's polarizability power. The tendency of an anion to be polarized and distorted by a cation is its polarizability. An ion with greater ionic radius is more polarizable because the electrons are held less closely to the nucleus.
Wed Nov 14, 2018 10:07 am
Forum: Dipole Moments
Topic: Dipole Moments [ENDORSED]
Replies: 10
Views: 441

### Re: Dipole Moments[ENDORSED]

Can someone please explain the difference between an induced dipole, dipole moment, and dipole-dipole interaction? When would you observe one versus the others?
Tue Nov 06, 2018 10:42 am
Forum: Lewis Structures
Topic: Sodium Hypochlorite
Replies: 2
Views: 184

### Re: Sodium Hypochlorite

The prefix hypo- tells you how many oxygen atoms there are in the compound. For polyatomic ions, the -ate suffix is the original form which is often best to memorize. Then, as the previous comment showed, the number of oxygen atoms changes with the prefixes/suffixes. The prefix per- means that you a...
Tue Nov 06, 2018 10:35 am
Forum: Ionic & Covalent Bonds
Topic: electronegativity difference
Replies: 4
Views: 224

### Re: electronegativity difference

I believe that if the electronegativity difference falls between 1.5 and 2, that it is a case by case basis. I think that depending on which types of elements are involved in the bond (metal, metalloid, nonmetal) you can determine whether it is ionic or covalent. If it is covalent, it will very like...
Tue Nov 06, 2018 10:19 am
Forum: Ionic & Covalent Bonds
Topic: Identifying compounds
Replies: 2
Views: 137

### Re: Identifying compounds

As for right now, I think we would be given formulas for the compounds. However, in the future we may need to memorize some of the most common ions and polyatomic ions. As the previous comment mentioned, you can usually determine whether a bond is ionic or covalent based on the classification of eac...
Wed Oct 31, 2018 7:07 pm
Forum: Octet Exceptions
Topic: Expanded Valence Shells
Replies: 2
Views: 206

### Expanded Valence Shells

During lecture, Dr. Lavelle mentioned that the reason why atoms can accommodate more than 8 valence electrons is because they have d orbitals in the valence shell that accommodate additional electrons. Does this mean that any atom that has a energy level of 3 or higher on the periodic table can have...
Wed Oct 31, 2018 6:55 pm
Forum: Resonance Structures
Topic: resonance hybrids
Replies: 4
Views: 169

### Re: resonance hybrids

Resonance hybrids basically represent the multiple Lewis structures with a double headed arrow combined into a single Lewis structure. A molecule's resonance hybrid is an average of all the possible resonance structures it can form. The dotted lines represent a possible bond that could be formed in ...
Wed Oct 31, 2018 6:41 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 4
Views: 221

### Re: Lewis Structures

Boron is an exception to the octet rule. This occurs because a coordinate covalent bond is formed. In coordinate covalent bonds, one of the two atoms involved in the bond provides both of the shared electrons as opposed to each atom involved in the bond providing one electron. Additionally, if you w...
Wed Oct 24, 2018 5:19 pm
Forum: Trends in The Periodic Table
Topic: Removing 2nd Electron
Replies: 9
Views: 339

### Re: Removing 2nd Electron

The second electron is more difficult to remove because after the first electron is removed, the atom has a positive net charge. This means that there are now more protons in the atom than electrons so there is a stronger attraction between the positive nucleus and the remaining electrons. This incr...
Wed Oct 24, 2018 5:14 pm
Forum: Trends in The Periodic Table
Topic: Isoelectronic Clarification
Replies: 2
Views: 112

### Re: Isoelectronic Clarification

I think the main thing that you have to know is that they have the same number of electrons. I think the biggest difference between isoelectronic atoms and ions is the net charge, which could have some effect on some of their properties, especially ionization energy. For example hydrogen and lithium...
Wed Oct 24, 2018 5:09 pm
Forum: Trends in The Periodic Table
Topic: Atomic, Covalent, and Ionic Radius
Replies: 5
Views: 286

### Atomic, Covalent, and Ionic Radius

During lecture, Dr. Lavelle went over atomic, covalent, and ionic radius. I know that the definition of covalent and atomic radii are the same so I was wondering what the difference between the two are? Also is the definition for how to find the ionic radius the same as covalent and atomic? Lastly, ...
Sat Oct 20, 2018 12:57 am
Forum: Properties of Light
Topic: Atomic Spectrum and Series
Replies: 4
Views: 80

### Re: Atomic Spectrum and Series

To clarify a little bit for you, the series are classified based on their similar wavelengths. This means they fall near each other on a light spectrum. The series are differentiated based on the shell that the electrons in those series relax to. So, you are correct when you say that in the Lyman se...
Sat Oct 20, 2018 12:43 am
Forum: Properties of Electrons
Topic: Balmer vs Lyman Series [ENDORSED]
Replies: 5
Views: 281

### Re: Balmer vs Lyman Series[ENDORSED]

As the previous post mentioned, the Lyman series corresponds to UV light and the electrons in the Lyman series relax to the n=1 shell. This will always be true of the Lyman series and its just something to memorize. The Balmer series corresponds with visible light and the electrons relax to the n=2 ...
Sat Oct 20, 2018 12:34 am
Forum: Properties of Electrons
Topic: Light vs Electron
Replies: 1
Views: 59

### Light vs Electron

I know that light has wave particle duality ( the ability to behave both as a wave and as a particle) but does this apply to electrons too?
Wed Oct 10, 2018 9:46 pm
Forum: SI Units, Unit Conversions
Topic: Atoms and Molecules
Replies: 5
Views: 174

### Re: Atoms and Molecules

Although atoms and molecules are different, you convert them from moles in the same way. For both atoms and molecules, you would use Avogadro's number. Therefore, for every 1 mole of a compound or substance there are 6.022x10^23 atoms or molecules. Whatever the problem specifies, you would use that ...
Wed Oct 10, 2018 10:12 am
Forum: Properties of Light
Topic: Light acts as a wave or not?
Replies: 10
Views: 253

### Re: Light acts as a wave or not?

Light acts as both a wave and a particle. When dealing with quantum mechanics, light is assumed to act as a particle and is absorbed and emitted in discrete units. However, it also has wave like qualities, such as electromagnetic radiation, wavelength, and frequency. I believe that we go over light'...
Tue Oct 09, 2018 4:59 pm
Forum: Significant Figures
Topic: Sig Fig zero rules
Replies: 7
Views: 783

### Re: Sig Fig zero rules

In simple terms, the significant figures are all the numbers, including zeros, that follow the first non zero digit. The exception to that statement is a number like 70 or 200, which only has one significant figure unless specified with a period after the zero (70. or 200.) You would then include th...
Thu Oct 04, 2018 2:49 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Molecules vs Formula Units? E21
Replies: 2
Views: 87

### Re: Molecules vs Formula Units? E21

I don't believe there is any difference when calculating for molecules vs formula units. In both cases you would use Avogadro's number to convert them to moles. The biggest difference between the two is that a molecule refers to covalently bonded compounds and formula units involve ionic bonds.
Thu Oct 04, 2018 2:40 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Replies: 9
Views: 575