Search found 52 matches
- Sat Mar 17, 2018 8:50 pm
- Forum: Phase Changes & Related Calculations
- Topic: Delta T and Sig Figs
- Replies: 1
- Views: 989
Re: Delta T and Sig Figs
Yes, because they are measurements. Anything that is measured has to consider sig figs.
- Sat Mar 17, 2018 8:48 pm
- Forum: Balancing Redox Reactions
- Topic: determining cathode from anode
- Replies: 11
- Views: 1870
Re: determining cathode from anode
Check the standard cell potentials.
- Sat Mar 17, 2018 8:47 pm
- Forum: Balancing Redox Reactions
- Topic: flipping the sign of anodes
- Replies: 5
- Views: 3224
Re: flipping the sign of anodes
You should always flip it and then if is asks for standard cell potential for the entire cell you can add the standards for the anode and cathode. If you don't flip it then then you subtract the anode from the cathode.
- Sat Mar 17, 2018 8:46 pm
- Forum: Balancing Redox Reactions
- Topic: Notation question
- Replies: 2
- Views: 506
Re: Notation question
The nitrogen goes from an overall -1 charge to a zero charge.
- Mon Mar 12, 2018 6:05 pm
- Forum: Zero Order Reactions
- Topic: Half Lives? [ENDORSED]
- Replies: 7
- Views: 1182
Re: Half Lives? [ENDORSED]
yes, because 1/4 is the half life of the half life.
- Mon Mar 12, 2018 6:03 pm
- Forum: Zero Order Reactions
- Topic: zero order rate?
- Replies: 14
- Views: 1567
Re: zero order rate?
That is definitely correct.
- Mon Mar 12, 2018 6:03 pm
- Forum: Zero Order Reactions
- Topic: Zero order
- Replies: 5
- Views: 1236
Re: Zero order
In a zero order reaction, the concentrations of the reactants does not effect the rate.
- Wed Feb 28, 2018 9:26 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Units of Reaction Rate
- Replies: 7
- Views: 909
Re: Units of Reaction Rate
we do not need to know any constants for this test
- Wed Feb 28, 2018 9:22 pm
- Forum: General Rate Laws
- Topic: Half life
- Replies: 3
- Views: 478
Re: Half life
They will be an equation given to us.
- Wed Feb 28, 2018 9:17 pm
- Forum: General Rate Laws
- Topic: Average Rate of Consumption of R
- Replies: 1
- Views: 289
Re: Average Rate of Consumption of R
That means that more reactants are produced.
- Mon Feb 26, 2018 7:06 pm
- Forum: Method of Initial Rates (To Determine n and k)
- Topic: Value of k
- Replies: 4
- Views: 538
Re: Value of k
The value of k cannot be negative because the reaction rate cannot be negative and the relationship we know is based on the concentrations and time not of k because k is constant for every reaction at a constant pressure and temperature.
- Mon Feb 26, 2018 7:04 pm
- Forum: Zero Order Reactions
- Topic: 15.9b
- Replies: 2
- Views: 383
Re: 15.9b
That is the concentration of the reactants and you are dividing by the concentration.
- Mon Feb 26, 2018 7:02 pm
- Forum: General Rate Laws
- Topic: Reaction rates
- Replies: 3
- Views: 466
Re: Reaction rates
Because at the start there is no products formed so the only concentration you have is the one of the reactants
- Thu Feb 22, 2018 12:06 am
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Oxidizing and Reducing Agents
- Replies: 2
- Views: 389
Re: Oxidizing and Reducing Agents
Look at the standard cell potentials.
- Thu Feb 22, 2018 12:05 am
- Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
- Topic: calculating n
- Replies: 9
- Views: 1192
Re: calculating n
You look at the electrons transferred during the half reactions.
- Thu Feb 22, 2018 12:04 am
- Forum: Balancing Redox Reactions
- Topic: Can solids have charges? [ENDORSED]
- Replies: 4
- Views: 2824
Re: Can solids have charges? [ENDORSED]
No because they are not ionized
- Mon Feb 12, 2018 11:11 am
- Forum: Calculating Work of Expansion
- Topic: When to use this equation
- Replies: 4
- Views: 541
Re: When to use this equation
That equation is used when the pressure is constant.
- Mon Feb 12, 2018 11:09 am
- Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
- Topic: Heat Capacity
- Replies: 2
- Views: 395
Heat Capacity
When do you use the heat capacity of water vs. the heat capacity of ice?
- Mon Feb 12, 2018 11:07 am
- Forum: Phase Changes & Related Calculations
- Topic: Units for Internal Energy
- Replies: 5
- Views: 707
Re: Units for Internal Energy
It can be either one. Just depends on the problem.
- Sat Feb 03, 2018 8:41 pm
- Forum: Entropy Changes Due to Changes in Volume and Temperature
- Topic: Assume ideal gas?
- Replies: 4
- Views: 550
Re: Assume ideal gas?
Yes, because it is an assumption to make calculations easier.
- Sat Feb 03, 2018 8:30 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: ΔS(universe)
- Replies: 6
- Views: 887
Re: ΔS(universe)
The change in entropy of the universe is the same always.
- Sat Feb 03, 2018 8:23 pm
- Forum: Gibbs Free Energy Concepts and Calculations
- Topic: When to use Q versus K [ENDORSED]
- Replies: 6
- Views: 2604
Re: When to use Q versus K [ENDORSED]
You use Q when the reaction is not at equilibrium and use K when the reaction is at equilibrium.
- Sun Jan 28, 2018 7:13 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Example 9.2
- Replies: 2
- Views: 358
Re: Example 9.2
It uses Cv,m because there is a constant volume so they can use that heat capacity.
- Sun Jan 28, 2018 7:12 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Reversible vs. Irreversible
- Replies: 3
- Views: 421
Reversible vs. Irreversible
What is the difference between reversible and irreversible expansion?
- Sun Jan 28, 2018 7:10 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: What is the difference between internal energy and molar internal energy? [ENDORSED]
- Replies: 2
- Views: 2964
Re: What is the difference between internal energy and molar internal energy? [ENDORSED]
Internal energy is the total amount of energy in a system. The molar internal energy is the energy of the system per mole.
- Sun Jan 21, 2018 10:14 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Enthalpies
- Replies: 7
- Views: 808
Re: Bond Enthalpies
Because when the bond enthalpy is less it takes less energy to break therefore, it is less stable. Bonds that take more energy are more stable because more energy is need to break the bonds.
- Sun Jan 21, 2018 10:12 pm
- Forum: Phase Changes & Related Calculations
- Topic: About phase change for methane in the combustion reaction
- Replies: 2
- Views: 403
Re: About phase change for methane in the combustion reaction
No, you assume that the water is in the liquid state the entire time.
- Sun Jan 21, 2018 10:11 pm
- Forum: Phase Changes & Related Calculations
- Topic: What mass of SO2 must be evaporated?
- Replies: 1
- Views: 1037
Re: What mass of SO2 must be evaporated?
Yup. You would convert kcal to kj and mass to moles.
- Mon Jan 15, 2018 5:15 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Enthalpy
- Replies: 2
- Views: 315
Re: Enthalpy
The reverse will be exothermic because it will have a negative enthalpy.
- Mon Jan 15, 2018 5:13 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Hess's Law
- Replies: 3
- Views: 359
Re: Hess's Law
Hess's Law allows you to calculate enthalpy using products and reactants.
- Mon Jan 15, 2018 5:10 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Ch. 8 #15 Part d
- Replies: 2
- Views: 354
Re: Ch. 8 #15 Part d
This is true when w=0 because q has to be 0 so it is only true when both q is 0 and w is 0.
- Wed Dec 06, 2017 10:04 pm
- Forum: Bronsted Acids & Bases
- Topic: Net Ionic Equations
- Replies: 2
- Views: 839
Re: Net Ionic Equations
In a net ionic equation, you only write what is actually reacting. For example, if you put the salt NaF in water it would completely dissociate but the Na+ will not react with anything. So the net ionic equation would be F- + H20 <--> HF + OH- instead of F- + H20 + Na+ <--> HF + OH- + Na+.
- Sun Dec 03, 2017 3:55 pm
- Forum: Bronsted Acids & Bases
- Topic: Identifying Bronsted Acids and Bases [ENDORSED]
- Replies: 3
- Views: 792
Re: Identifying Bronsted Acids and Bases [ENDORSED]
A bronsted acid usually has a H+ that will be donated while a bronsted acid will usually have an OH- it will donate.
- Fri Dec 01, 2017 11:09 am
- Forum: Lewis Acids & Bases
- Topic: Lewis Structure
- Replies: 3
- Views: 534
Re: Lewis Structure
The lewis structure of a lewis acid will not have a lone pair while an lewis base will have a lone pair to donate.
- Fri Dec 01, 2017 11:05 am
- Forum: Ideal Gases
- Topic: Temperature in PV=nRT
- Replies: 9
- Views: 1110
Re: Temperature in PV=nRT
The standard units for temperature is Kelvin (K)
- Mon Nov 27, 2017 12:20 am
- Forum: Equilibrium Constants & Calculating Concentrations
- Topic: Equilibrium Constant units
- Replies: 2
- Views: 320
Re: Equilibrium Constant units
It does not have units because it is just a ratio and ratios do not have units.
- Mon Nov 20, 2017 11:29 pm
- Forum: Naming
- Topic: bisoxalato
- Replies: 1
- Views: 449
bisoxalato
What does bisoxalato mean?
- Fri Nov 17, 2017 11:07 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs Angular
- Replies: 7
- Views: 777
Re: Bent vs Angular
The word angular and bent mean the exact same thing. Don’t worry about when to use either. They are the same.
- Fri Nov 17, 2017 11:06 am
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bent vs Angular
- Replies: 7
- Views: 777
Re: Bent vs Angular
The word angular and bent mean the exact same thing. Don’t worry about when to use either. They are the same.
- Fri Nov 17, 2017 11:02 am
- Forum: Hybridization
- Topic: Triple bond sigma vs. pi
- Replies: 3
- Views: 357
Re: Triple bond sigma vs. pi
A triple bond contains 1 sigma and 2 pi bonds because only one sigma bond can be created between 2 molecules so the other 2 have to be pi bonds.
- Wed Nov 08, 2017 5:37 pm
- Forum: Formal Charge and Oxidation Numbers
- Topic: Sulfur Dioxide?
- Replies: 3
- Views: 628
Re: Sulfur Dioxide?
A sulfur dioxide molecule is always changing so in reality it is a blend of all 3 but it is in the state with the lowest formal charge the majority of the time.
- Wed Nov 08, 2017 5:35 pm
- Forum: Lewis Structures
- Topic: Lewis Structure of N2O
- Replies: 2
- Views: 616
Re: Lewis Structure of N2O
The structure with oxygen have a -1 charge is the most stable because oxygen is already very electronegative. It is the one with the lowest energy.
- Sun Nov 05, 2017 10:14 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Lewis Structures
- Replies: 6
- Views: 763
Re: Lewis Structures
This is the actually shape of the orbital with a 3d shape. It has been determined by flashing light.
- Sun Nov 05, 2017 10:10 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Formal charge and lewis structures
- Replies: 5
- Views: 594
Re: Formal charge and lewis structures
I do not think you have to draw all of the possible ones. If the first one you draw has a formal charge of 0 then you don't have to draw anymore.
- Sat Oct 28, 2017 2:45 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Determining valence electrons for d-block elements [ENDORSED]
- Replies: 3
- Views: 13150
Re: Determining valence electrons for d-block elements [ENDORSED]
We are only considered with the valence shell electrons so that is the s and p orbitals and we will only be working with those.
- Sat Oct 28, 2017 2:40 pm
- Forum: Trends in The Periodic Table
- Topic: atomic size
- Replies: 4
- Views: 686
Re: atomic size
yes I agree, elements on the top left are smaller than elements on the bottom right side of the periodic table.
- Fri Oct 20, 2017 10:08 am
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect as Proof of Particle Qualities of Light
- Replies: 3
- Views: 730
Re: Photoelectric Effect as Proof of Particle Qualities of Light
It is proved by the fact that when you increase the intensity, there is no change. That means that it is dependent on the individual particle and not on the wave as a whole.
- Fri Oct 20, 2017 10:05 am
- Forum: Photoelectric Effect
- Topic: Rydberg
- Replies: 11
- Views: 1642
Re: Rydberg
When using Rydberg's equation, the frequency cannot be negative. To avoid this you put whatever the higher of the 2 energy levels for n1.
- Fri Oct 13, 2017 11:15 am
- Forum: Einstein Equation
- Topic: Lyman and Blamer series [ENDORSED]
- Replies: 7
- Views: 1173
Re: Lyman and Blamer series [ENDORSED]
You can determine what series it is by the smallest energy level so if n1 is 1 and n2 is 3, it is still a Lyman series and if n1 is 2 and n2 is 6, it is still a Balmer series.
- Fri Oct 13, 2017 11:12 am
- Forum: Properties of Light
- Topic: Speed of Light Constant
- Replies: 18
- Views: 1733
Re: Speed of Light Constant
When it comes to constants, use the sig figs that are given in the problem to determine how many values past the decimal point to us in the speed of light constant or plank's constant.
- Thu Oct 05, 2017 8:06 pm
- Forum: Significant Figures
- Topic: Significant Figures of Conversion Factors [ENDORSED]
- Replies: 3
- Views: 15329
Re: Significant Figures of Conversion Factors [ENDORSED]
The conversion factors do not count for sig figs because they are exact values and are not measurements that is why it does not matter.
- Thu Oct 05, 2017 7:53 pm
- Forum: Significant Figures
- Topic: E29 (d) Significant Figures
- Replies: 3
- Views: 486
Re: E29 (d) Significant Figures
This is a mistake in the solution manual. You should use the sig. figs. that are given in the question and not from the periodic table because the periodic table can vary.