Search found 30 matches

Fri Mar 15, 2019 1:58 pm
Forum: General Rate Laws
Topic: k'
Replies: 3
Views: 144

Re: k'

k' is the rate constant for the reverse reaction, and the K ( equilibrium constant ) would be equal to k ( forward reaction ) / k' ( reverse reaction )
Fri Mar 15, 2019 1:57 pm
Forum: General Rate Laws
Topic: Determining the order
Replies: 3
Views: 170

Re: Determining the order

You will definitely be given different trials of the reaction, the rates and the concentrations!
Fri Mar 15, 2019 1:56 pm
Forum: General Rate Laws
Topic: Final Equations
Replies: 4
Views: 189

Re: Final Equations

I think you should know all the chemical kinetic order reactions, that we use to graph.
Thu Mar 07, 2019 1:52 am
Forum: Zero Order Reactions
Topic: Slope = -k
Replies: 3
Views: 184

Re: Slope = -k

This only means that integrating gives different values, and k would be negative or positive, depending on the equation.
Thu Mar 07, 2019 1:50 am
Forum: Zero Order Reactions
Topic: zero order rate?
Replies: 14
Views: 856

Re: zero order rate?

This is true. For a zero order, Rate = K(conc) raised to power 0. So it is just K.
Thu Mar 07, 2019 1:49 am
Forum: Zero Order Reactions
Topic: Example of a zero order rxn
Replies: 4
Views: 186

Re: Example of a zero order rxn

Zero order is where the reactants are in excess and is a solvent/ liquid and hence the change in its concentration would just be insignificant.
Tue Feb 26, 2019 8:32 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Reducing Agent/ Oxidizing Agent Strength in Metals
Replies: 3
Views: 212

Re: Reducing Agent/ Oxidizing Agent Strength in Metals

The more positive the reduction potential, the more favourable it is to get reduced, and thus, the better oxidising agent it is.
And the same is true vice versa.
Tue Feb 26, 2019 8:29 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Writing Cell Diagrams
Replies: 3
Views: 109

Re: Writing Cell Diagrams

We include an inert electrode when either the anode and cathode are either gas/aqueous and both the reactants and the products are in that same phase.
So for example,
A hydrogen( gas ) electrode would require a platinum electrode.
Tue Feb 26, 2019 8:28 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Moles of electrons?
Replies: 6
Views: 233

Re: Moles of electrons?

The only way of knowing n is by balancing the half reactions - so, that the electrons lost and gained tally.
Wed Feb 20, 2019 10:25 pm
Forum: Balancing Redox Reactions
Topic: flipping the sign of anodes
Replies: 5
Views: 1048

Re: flipping the sign of anodes

You will have to flip it if it is not given in terms of reduction potential.
Wed Feb 20, 2019 10:24 pm
Forum: Balancing Redox Reactions
Topic: determining cathode from anode
Replies: 11
Views: 767

Re: determining cathode from anode

The cathode is where it is reduction, and thus, the potential will be positive(because it is always written in terms of reduction potential) and the other one will be the anode(which causes oxidation to occur - loss of electrons which we can see from the equation given), and thus we know that is the...
Wed Feb 20, 2019 10:20 pm
Forum: Balancing Redox Reactions
Topic: H+ vs H3O+
Replies: 10
Views: 360

Re: H+ vs H3O+

It is better to use H+ because H30+ would cause us to balance oxygen again, and thus, H+ would be a better option to use.
Thu Feb 14, 2019 3:55 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Stability
Replies: 3
Views: 145

Re: Stability

It all depends first on whether the equation represents an exothermic or endothermic reaction.
If G is negative, it is said to be a spontaneous reaction.
Thu Feb 14, 2019 3:53 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: ΔU= 3/2nRT
Replies: 5
Views: 315

Re: ΔU= 3/2nRT

We can use it, for ideal gases and monoatomic ones, but with the plethora of equations we have, we would mostly never come across a time to use it.
Mon Feb 11, 2019 3:21 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Test Question
Replies: 2
Views: 128

Test Question

What would the right answer be in the last question of the test? How would we go about it: b) Consider the above reaction at equilibrium ( Kc= 0.046 given above), fully describe what will happen if the volume is decreased at constant temperature. How do I do this question? if volume decreases, conce...
Wed Feb 06, 2019 10:40 pm
Forum: Calculating Work of Expansion
Topic: Degeneracy
Replies: 6
Views: 317

Re: Degeneracy

Degeneracy is determined as the number of atoms involved raised to the power of possible states.
Wed Feb 06, 2019 9:36 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Entropy as Temperature Increases
Replies: 2
Views: 126

Re: Entropy as Temperature Increases

Here, we notice the average change. If the temperature is already very high, then the particles are already moving around a lot and fast, so the change in disorder would be minuscule. But from a low temperature system, the change in the disorder is more visible, and hence the entropy change is highl...
Thu Jan 31, 2019 6:23 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Reversible Processes
Replies: 2
Views: 140

Re: Reversible Processes

In a reversible process, it is the sum of infinitely small steps and leads to the expending of the entire energy of the system, and thus is said to be most work done. This never happens in reality, and thus reversible systems are said to be an ideal system. Whereas, in irreversible processes, not al...
Thu Jan 31, 2019 6:21 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy Symbol
Replies: 5
Views: 327

Re: Enthalpy Symbol

The naught sybol stands for absolute value, thus, its value at standard conditions, almost like its ideal value, when all conditions are said to be standard. This requires the pressure and temperature to be a particular value. And while measuring other values of H, we use this value as the reference...
Thu Jan 31, 2019 6:19 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: steam vs. water
Replies: 5
Views: 305

Re: steam vs. water

It is because, although the temperature of steam is 100 degree Celsius as well, it contains more heat that is used up to change the phase from water to steam. And this heat is also instrumental in burns, and is clearly missing in just water at 100 degree Celsius. Thus, steam causes more of a burn th...
Thu Jan 24, 2019 9:56 am
Forum: Phase Changes & Related Calculations
Topic: Endothermic or Exothermic
Replies: 20
Views: 913

Re: Endothermic or Exothermic

Its exothermic, because it releases heat and is the opposite of the process that requires heat to change phase.
Thu Jan 24, 2019 9:54 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpy and q
Replies: 3
Views: 101

Re: Enthalpy and q

Enthalpy is denoted by delta H and that is only final - initial and is a state property.
q though, he will explain further but it denotes the value of heat and that depends on its entire path, where it gains/loses heat.
Thu Jan 24, 2019 9:50 am
Forum: Phase Changes & Related Calculations
Topic: How to tell acids and bases
Replies: 8
Views: 257

Re: How to tell acids and bases

Usually, the list of acids and bases remain a constant and we always know what they give us.
But if not, we have to figure out from the lewis structures after we draw them, or from the very formula, if it is given.
Tue Jan 15, 2019 6:32 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: question from module
Replies: 4
Views: 196

Re: question from module

Same number of moles, so no change in direction of equilibrium!
And temperature is as explained above.
Tue Jan 15, 2019 6:31 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Part 4 Post-Module Question
Replies: 4
Views: 313

Re: Part 4 Post-Module Question

If delta H is positive, the increase in temperature will favour forward reaction, and if delta H is negative, it favours reverse reaction.
Tue Jan 15, 2019 6:29 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: test 1 [ENDORSED]
Replies: 7
Views: 332

Re: test 1[ENDORSED]

It includes chemical equilibrium, Le Chatelier's principle, as well as acids and bases.
Fri Jan 11, 2019 9:30 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Effect of Pressure
Replies: 3
Views: 90

Effect of Pressure

I am aware that change in pressure does not affect the equilibrium constant K, but when I googled it, it said when there is an increase in pressure, the reaction shifts towards the direction of lesser number of moles, and there is a decrease in pressure, then it shifts towards the side with more mol...
Thu Jan 10, 2019 12:25 pm
Forum: Ideal Gases
Topic: Units
Replies: 5
Views: 158

Re: Units

In most questions, pressure is usually in atm, so use an appropriate R and make all units cancel out!
Thu Jan 10, 2019 12:22 pm
Forum: Ideal Gases
Topic: Q and K [ENDORSED]
Replies: 35
Views: 1735

Re: Q and K[ENDORSED]

Virtually no difference between how we calculate Q and K, but they just tell us different things ( which - either reactant or product is in excess and which side the equilibrium sits)
Thu Jan 10, 2019 12:21 pm
Forum: Ideal Gases
Topic: Reaction Quotient
Replies: 5
Views: 243

Reaction Quotient

Only Kp is measured in terms of partial pressure, always? when it comes to a reaction that is homogeneous (gas), but both Kc and even Qc are always measured in terms of concentration?

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