Search found 33 matches
- Sun Mar 18, 2018 6:20 pm
- Forum: General Rate Laws
- Topic: rate law
- Replies: 6
- Views: 1020
Re: rate law
no rate laws don't include products you are thinking of the equilibrium constant
- Sun Mar 18, 2018 6:19 pm
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Transition State
- Replies: 3
- Views: 629
Re: Transition State
It is the peak because it has the highest energy since the carbons have 5 bonding groups around them during that small amount of time, making it highly unstable
- Sun Mar 18, 2018 6:17 pm
- Forum: First Order Reactions
- Topic: k' in Pseudo-First-Order Rate Laws
- Replies: 4
- Views: 1557
Re: k' in Pseudo-First-Order Rate Laws
k' stands for k*the reactants that you don't use in the rate law
- Tue Mar 13, 2018 11:16 am
- Forum: Second Order Reactions
- Topic: Half life
- Replies: 6
- Views: 984
Re: Half life
it is 1/(1/16) making it 16/1 (it flips); just plug it into the equation and you should be fine
- Tue Mar 13, 2018 11:15 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: How does a homogeneous catalyst affect (a) the rate law; (b) the equilibrium constant? [ENDORSED]
- Replies: 5
- Views: 1164
Re: How does a homogeneous catalyst affect (a) the rate law; (b) the equilibrium constant? [ENDORSED]
part a increases because catalysts increase the rate of the reaction in general
- Tue Mar 13, 2018 11:12 am
- Forum: Arrhenius Equation, Activation Energies, Catalysts
- Topic: Homogeneous Catalysts
- Replies: 3
- Views: 534
Re: Homogeneous Catalysts
its just an observed trait
- Tue Mar 06, 2018 10:57 am
- Forum: General Rate Laws
- Topic: Concentration and Rate Relationship
- Replies: 4
- Views: 604
Re: Concentration and Rate Relationship
for multiple reactions, see the effect of each reactant on the rate. so if one reactant is 1st order and another is 2nd order, the 1st would double the rate if the concentration is doubled and the 2nd one would quadruple the rate if the concentration was doubled. you usually view them separately lik...
- Tue Mar 06, 2018 10:55 am
- Forum: General Rate Laws
- Topic: How the concentration of a reactant affects the rate of the reaction
- Replies: 3
- Views: 399
Re: How the concentration of a reactant affects the rate of the reaction
depending on order, raise the effect on the concentration to that power to see the effect on the rate. for example if we double the concentration of a 1st order than you do 2^1 (1 because 1st order) which equals 2 meaning the rate will also be doubled. for 2nd order it would be 2^2 meaning the rate ...
- Tue Mar 06, 2018 10:52 am
- Forum: General Rate Laws
- Topic: When to Use Avg. vs Instantaneous
- Replies: 5
- Views: 585
Re: When to Use Avg. vs Instantaneous
you can also usually tell by what is given in the problem. for example if it doesn't give an order but gives you a rate then its most likely average rate instead of instantaneous
- Tue Feb 27, 2018 10:03 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: signs
- Replies: 6
- Views: 1134
Re: signs
we dont want to be talking about "negative" rates so we add the negative when talking about the rates of the reactants since they are decreasing and their rate would normally be negative (adding the negative makes it positive, which we want, this also represents rate of products)
- Tue Feb 27, 2018 10:01 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: units of the rate of reaction
- Replies: 7
- Views: 1035
Re: units of the rate of reaction
theres a pattern to it as you can see in the previous responses so for 2nd reaction the L and mol gets raised to 2nd power and 3rd reaction gets raised to 3rd power and so on; seconds remain just seconds
- Tue Feb 27, 2018 9:59 pm
- Forum: Kinetics vs. Thermodynamics Controlling a Reaction
- Topic: Slowest Elementary Step
- Replies: 4
- Views: 816
Re: Slowest Elementary Step
We need the longest time taken for products to be formed or else that slowest step would not be able to be completed; if the slowest step takes 10 seconds but every other step only takes 1, you still need to give the reaction 10 seconds to complete that slow step
- Fri Feb 23, 2018 2:14 pm
- Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
- Topic: Cell Diagrams [ENDORSED]
- Replies: 7
- Views: 860
Re: Cell Diagrams [ENDORSED]
they are inert so that they will not change the reaction but will act as electron transporters to allow the redox reaction to occur
- Fri Feb 23, 2018 2:05 pm
- Forum: Balancing Redox Reactions
- Topic: Reaction E [ENDORSED]
- Replies: 5
- Views: 714
Re: Reaction E [ENDORSED]
E values never change, even if the chemical reaction is being multiplied by a factor
- Fri Feb 23, 2018 2:03 pm
- Forum: Balancing Redox Reactions
- Topic: Cell Diagram [ENDORSED]
- Replies: 7
- Views: 884
Re: Cell Diagram [ENDORSED]
The only time they aren't going to be separated by lines is when they are both the same state such as two aqueous solutions
- Sun Feb 18, 2018 4:11 pm
- Forum: Balancing Redox Reactions
- Topic: Balancing Redox reactions
- Replies: 3
- Views: 533
Re: Balancing Redox reactions
you need to balance O first because you will only know how much H you need once you get the right amount of O
- Sun Feb 18, 2018 4:09 pm
- Forum: Balancing Redox Reactions
- Topic: agents
- Replies: 3
- Views: 489
Re: agents
an agent is just the thing that does the action so for an oxidizing agent it is the thing that does the oxidizing
- Sun Feb 18, 2018 4:07 pm
- Forum: Phase Changes & Related Calculations
- Topic: Specific heat of water or ice?
- Replies: 6
- Views: 1120
Re: Specific heat of water or ice?
I get confused with this a lot to but you just have to know that under 0 degrees Celsius will be ice and above will be water and if its at 0 degrees it will usually tell you what current state its in
- Wed Feb 07, 2018 3:28 pm
- Forum: Balancing Redox Reactions
- Topic: Ozone oxidation number
- Replies: 2
- Views: 299
Re: Ozone oxidation number
O3 is a neutral substance so it's oxidation number is 0 (there is no negative or positive charge on the compound)
- Wed Feb 07, 2018 3:25 pm
- Forum: Balancing Redox Reactions
- Topic: Transition Metals
- Replies: 4
- Views: 506
Re: Transition Metals
you basically need to rely on the other element in the compound as Audrey said to determine the oxidation state in that situation
- Wed Feb 07, 2018 3:23 pm
- Forum: Balancing Redox Reactions
- Topic: oxidation
- Replies: 4
- Views: 542
Re: oxidation
you essentially look at the elements location in the periodic table. if it is in the first two groups, it will be +1 and +2 (the group number) and if it is in the last couple of groups, it will be -3, -2, -1 (corresponding to group 15, 16, 17)
- Sun Feb 04, 2018 5:56 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: The sign of the change in Gibb's Free Energy
- Replies: 6
- Views: 798
Re: The sign of the change in Gibb's Free Energy
when deltaG is negative, that means deltaS of the universe (total) is positive since deltaS(total)=-(deltaG)/T. deltaS being positive means the reaction is spontaneous (thus deltaG needs to be negative)
- Sun Feb 04, 2018 5:47 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: Test Number 1
- Replies: 9
- Views: 1083
Re: Test Number 1
doing work while maintaining a constant temp needs to include a heat transfer in order to maintain the constant temperature (q=-w or w=-q)
- Sun Feb 04, 2018 5:44 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: q=-w [ENDORSED]
- Replies: 5
- Views: 904
Re: q=-w [ENDORSED]
This formula is true for instances of isothermal expansions since having deltaT=0 (no change in temp), then deltaU (internal energy) would be 0 and since deltaU=q+w, then q would equal -w
- Sun Jan 28, 2018 5:51 pm
- Forum: Concepts & Calculations Using First Law of Thermodynamics
- Topic: isothermal system
- Replies: 3
- Views: 456
Re: isothermal system
The important part is isothermal, meaning deltaT would be 0 making deltaU 0 (since anything *0=0).
- Sun Jan 28, 2018 5:37 pm
- Forum: Concepts & Calculations Using Second Law of Thermodynamics
- Topic: Spontineity
- Replies: 5
- Views: 700
Re: Spontineity
Also spontaneous reactions with gas can't occur while going to a smaller volume because that would require energy but larger volume wouldn't need anything to happen
- Sun Jan 28, 2018 5:22 pm
- Forum: Calculating Work of Expansion
- Topic: The integral equation
- Replies: 8
- Views: 739
Re: The integral equation
I also don't believe we will actually have to derive anything on the tests because it isn't the point of the equation. We only derived it to help us understand where it came from.
- Thu Jan 18, 2018 10:23 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bong Enthalpy accuracy [ENDORSED]
- Replies: 3
- Views: 345
Re: Bong Enthalpy accuracy [ENDORSED]
I think when we are given the question, there will be only one method that fits the question so I don't think you would have much of a choice to not use this method but it is just worth knowing that this method is the least accurate.
- Thu Jan 18, 2018 10:20 am
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Bond Breaking or forming
- Replies: 5
- Views: 595
Re: Bond Breaking or forming
In response to your latest question, you would just notice that a bond in the reactants had been broken and a new bond in the products is formed because there are different combinations. For example, if we have CH4 + HBr --- CH4Br and we drew the lewis structures, we would see that the double carbon...
- Mon Jan 15, 2018 3:10 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: HW Ch.8 #59 and 63
- Replies: 7
- Views: 659
Re: HW Ch.8 #59 and 63
I am confused about this as well because in both questions 59 and 63 they are asking for the standard reaction enthalpy for the reactions and 59 uses kJ/mol while 63 only uses kJ. The questions are basically identical except for the reactions so how do we know when to use one or the other?
- Sat Jan 13, 2018 5:58 pm
- Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
- Topic: Sig Figs for Question 8.45 (a)
- Replies: 5
- Views: 524
Re: Sig Figs for Question 8.45 (a)
I've heard that if the answer ends in .5, you would round to the nearest even number, which in this case would be 448. I am not sure if this is the official rule to go by but I remember reading it in 14A so maybe that would explain it.
- Sat Jan 13, 2018 5:49 pm
- Forum: Phase Changes & Related Calculations
- Topic: Phase Changes
- Replies: 13
- Views: 1556
Re: Phase Changes
An easy way to think about this is that exothermic releases heat, meaning usually involving cooling, so the phase changes being exothermic would be from gas to liquid (condensation), liquid to solid (freezing), or gas to solid.
- Fri Jan 12, 2018 2:39 pm
- Forum: Phase Changes & Related Calculations
- Topic: Heating Curve
- Replies: 6
- Views: 555
Re: Heating Curve
Does the length of the sloped lines indicate anything? Or is it just based on the steepness?