Search found 28 matches

by Maria Bajenov 1I
Sat Mar 17, 2018 8:22 pm
Forum: General Rate Laws
Topic: number of mols effect on result
Replies: 2
Views: 248

Re: number of mols effect on result

Number of moles affects the molarity of the reactant. Molarity is stated in the rate law. Depending on if moles increases of decreases, the molarity will be affected correspondingly.
by Maria Bajenov 1I
Sat Mar 17, 2018 8:20 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Irreversible reactions
Replies: 1
Views: 186

Re: Irreversible reactions

Why can you say that all irreversible reactions are spontaneous? Wouldn't you need to do the calculation? How can this be true in general?
by Maria Bajenov 1I
Sat Mar 17, 2018 8:18 pm
Forum: Calculating Work of Expansion
Topic: Reversible vs Irreversible
Replies: 1
Views: 193

Re: Reversible vs Irreversible

w= -PdeltaV takes into account that the external pressure is constant. It produces less work than a reversible reaction because for the reversible reaction, exceptions are made that allow the system to be viewed as not losing energy to other factors.
by Maria Bajenov 1I
Sat Mar 10, 2018 2:10 pm
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Heterogenous vs homogenous
Replies: 2
Views: 147

Heterogenous vs homogenous

What determines if a heterogenous or homogenous catalyst should be used? What determines which is more effective?
by Maria Bajenov 1I
Sat Mar 10, 2018 2:08 pm
Forum: *Enzyme Kinetics
Topic: Km
Replies: 1
Views: 226

Km

How is Km a constant if it depends on concentrations of the enzyme and substrate?
by Maria Bajenov 1I
Sat Mar 10, 2018 2:03 pm
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Elementary Reaction Rate Law [ENDORSED]
Replies: 1
Views: 76

Elementary Reaction Rate Law [ENDORSED]

When writing the rate law for each step of the mechanism, how do we know whether to include the reverse reaction? How do we know if it is too slow to effect the rate?
by Maria Bajenov 1I
Sat Mar 03, 2018 8:20 pm
Forum: Second Order Reactions
Topic: Limiting Step
Replies: 7
Views: 455

Re: Limiting Step

Since we haven't covered activation energy, do we always determine the slow step with the determined rate law? Is there any other method we have learned to determine the slow step?
by Maria Bajenov 1I
Sat Mar 03, 2018 8:15 pm
Forum: General Rate Laws
Topic: Rate constant units
Replies: 2
Views: 122

Rate constant units

How would you use units of the rate constant to identify order of the reaction? (What units of molarity and time raised to powers are associated with each order?)
by Maria Bajenov 1I
Sat Mar 03, 2018 8:13 pm
Forum: First Order Reactions
Topic: Naming Orders
Replies: 3
Views: 174

Re: Naming Orders

Even though the overall reaction order is second, I believe the individual orders would both be first.
by Maria Bajenov 1I
Sat Feb 24, 2018 2:34 pm
Forum: General Rate Laws
Topic: Reaction Rate
Replies: 3
Views: 136

Re: Reaction Rate

I think it means to only look at reactants at the start of the reaction (initial rate). Why does the reaction rate depend only on concentration of reactants, but the reaction rate can be set equal to products as well? How is it allowed to just focus on initial rate of reactants?
by Maria Bajenov 1I
Sat Feb 24, 2018 2:31 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic vs electrochemical [ENDORSED]
Replies: 2
Views: 116

Galvanic vs electrochemical [ENDORSED]

What is the difference between a galvanic and electrochemical cell? Or is galvanic a type of electrochemical cell?
by Maria Bajenov 1I
Sat Feb 24, 2018 2:30 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Galvanic cell set up
Replies: 8
Views: 258

Galvanic cell set up

Since a galvanic cell corresponds to a spontaneous reaction, is the left side of the cell diagram always the anode?
by Maria Bajenov 1I
Sat Feb 10, 2018 3:31 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: Standard State
Replies: 2
Views: 96

Re: Standard State

If it is not in standard state, the values of deltaH differ because the temperature it is carried out at is not the temperature at which deltaH was measured. Therefore, the problem must be done in parts, separating the different temperatures and then combining all the values from each separate calcu...
by Maria Bajenov 1I
Sat Feb 10, 2018 12:23 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Entropy being a state function
Replies: 2
Views: 107

Entropy being a state function

Is it only important to note whether a reaction is irreversible or reversible if the variable we are solving for is not a state function and dependent on the path? So an entropy calculation of an irreversible reaction can be found using the reversible calculation and be the same?
by Maria Bajenov 1I
Sat Feb 10, 2018 12:19 pm
Forum: Van't Hoff Equation
Topic: Derivation
Replies: 9
Views: 425

Derivation

Since we go over derivations in lecture, is it necessary to know how to derive the equations we learn or simply how to use them?
by Maria Bajenov 1I
Sun Feb 04, 2018 9:44 am
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: qrev
Replies: 3
Views: 138

qrev

I'm confused as to what you insert for qrev in delta S? Is it -delta H or nCdeltaT? How do you know when to use which?
by Maria Bajenov 1I
Sun Feb 04, 2018 9:37 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: System vs Surrounding
Replies: 4
Views: 199

System vs Surrounding

In a given problem, how can you determine what is the system and what is the surroundings? When it states that a reaction occurs in the flask, how do you know that the surrounding is the flask, not the lab?
by Maria Bajenov 1I
Sun Feb 04, 2018 9:36 am
Forum: Gibbs Free Energy Concepts and Calculations
Topic: Spontaneity
Replies: 4
Views: 151

Spontaneity

Can a reaction be determined as spontaneous or not only by delta G?
by Maria Bajenov 1I
Sat Jan 27, 2018 9:32 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Internal energy as a state function
Replies: 3
Views: 162

Internal energy as a state function

How can internal energy be a state function if work (a component of it) is not?
by Maria Bajenov 1I
Sat Jan 27, 2018 9:31 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Systems in practice
Replies: 4
Views: 203

Systems in practice

Can any system truly be isolated or adiabatic in practice or only in theory?
by Maria Bajenov 1I
Sat Jan 27, 2018 9:27 am
Forum: Calculating Work of Expansion
Topic: Reversible vs Irreversible
Replies: 2
Views: 133

Reversible vs Irreversible

Does a reversible reaction always correspond to an isothermal system (because it is constant T) and an irreversible to an isobaric system (because constant P)? Or does P within the system change, and therefore, is it not isobaric?
by Maria Bajenov 1I
Sat Jan 20, 2018 12:18 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: ∆U = U final-U initial
Replies: 1
Views: 100

∆U = U final-U initial

When comparing U final and U initial to determine if ∆U is positive or negative, are there two different sets of values for q and w to calculate initial and final (since ∆U= q + w) or is it based on one set of data and then identified if final or initial was greater based on the value calculated?
by Maria Bajenov 1I
Sat Jan 20, 2018 12:09 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: When to use Cv or Cp? to calculate change in Entropy
Replies: 3
Views: 773

Re: When to use Cv or Cp? to calculate change in Entropy

It depends on the type of system the reaction is being carried out in. If the problem specifies that it is isothermal, use Cp. It it is being carried out in isochoric, use Cv. If it is isobaric, use Cp to calculate q because pressure is not changing and change in volume will be accounted for in calc...
by Maria Bajenov 1I
Sat Jan 20, 2018 11:59 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: ∆H equation
Replies: 3
Views: 143

∆H equation

For calculating ∆H, you solve for KJ(energy)/mol. The mol corresponds to n, but what constant corresponds to KJ?
by Maria Bajenov 1I
Sat Jan 13, 2018 10:43 am
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: hw 8.49
Replies: 1
Views: 83

Re: hw 8.49

Since the problem provides delta H and number of moles, there is a way to find delta U. It is possible to find delta T by the relationship between the C value that can be found in the table and the delta H value provided. Then solve for delta U by plugging in the values to the equation on page 280 (...
by Maria Bajenov 1I
Sat Jan 13, 2018 10:31 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Different Molar Heat Capacities For Gases
Replies: 5
Views: 227

Re: Different Molar Heat Capacities For Gases

For measuring heat transfer, the equation q=(n)(Cp)(delta T) relates molar heat capacity at a constant pressure with moles. If one were to change, the other would change accordingly. The relation changes if it is at constant volume instead.
by Maria Bajenov 1I
Sat Jan 13, 2018 10:20 am
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Specific heat capacity vs molar heat capacity
Replies: 5
Views: 169

Specific heat capacity vs molar heat capacity

Is molar heat capacity a type of specific heat capacity since it is per amount?

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