Search found 50 matches

by Diana Andrade_4F
Fri Mar 13, 2020 10:18 pm
Forum: First Order Reactions
Topic: rate constants
Replies: 19
Views: 104

Re: rate constants

Yes, they're always positive!
by Diana Andrade_4F
Fri Mar 13, 2020 9:54 pm
Forum: First Order Reactions
Topic: Units for t
Replies: 13
Views: 32

Re: Units for t

The units of t depend on the problem, but be consistent when doing calculations!
by Diana Andrade_4F
Fri Mar 13, 2020 8:50 pm
Forum: Administrative Questions and Class Announcements
Topic: "Open Book" Final?
Replies: 30
Views: 324

Re: "Open Book" Final?

We will be able to use our notes, textbook, and chemistry community! Exam should be short, but he said he'd give us 3-4 hours to complete it. He will give us more info on Saturday!
by Diana Andrade_4F
Fri Mar 13, 2020 8:45 pm
Forum: Student Social/Study Group
Topic: final?
Replies: 7
Views: 65

Re: final?

Lavelle will let us know more on Saturday, look out for his emails!
by Diana Andrade_4F
Fri Mar 13, 2020 8:43 pm
Forum: Administrative Questions and Class Announcements
Topic: Final
Replies: 11
Views: 77

Re: Final

Final will be up on Sunday, and it is timed (3-4 hours). Lavelle will let us know more info Saturday!
by Diana Andrade_4F
Fri Mar 06, 2020 11:34 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: change in gibbs free energy
Replies: 4
Views: 38

Re: change in gibbs free energy

Photosynthesis is not spontaneous and needs an input of energy in order for it to occur. So that's why the answer is ΔG<0
by Diana Andrade_4F
Fri Mar 06, 2020 11:31 pm
Forum: Balancing Redox Reactions
Topic: Oxidation Numbers
Replies: 7
Views: 68

Re: Oxidation Numbers

For some elements there will be a trend you should follow (look up a periodic table with these trends on google!), and for the unknown you can solve for. The oxidation numbers should add up to the total charge at the end.
by Diana Andrade_4F
Fri Mar 06, 2020 8:53 pm
Forum: General Science Questions
Topic: Test 2 Grades [ENDORSED]
Replies: 23
Views: 238

Re: Test 2 Grades [ENDORSED]

We will most likely get our test grades during discussion of week 10!
by Diana Andrade_4F
Fri Mar 06, 2020 1:10 am
Forum: Administrative Questions and Class Announcements
Topic: Test 2 Grades
Replies: 22
Views: 184

Re: Test 2 Grades

We will most likely get our test grades next week during discussion section
by Diana Andrade_4F
Fri Feb 28, 2020 8:38 pm
Forum: Interesting Applications: Rechargeable Batteries (Cell Phones, Notebooks, Cars), Fuel Cells (Space Shuttle), Photovoltaic Cells (Solar Panels), Electrolysis, Rust
Topic: Porous Disk and Salt Bridge
Replies: 13
Views: 341

Re: Porous Disk and Salt Bridge

Since they ultimately have the same function, I believe that one isn't more efficient than the other
by Diana Andrade_4F
Fri Feb 28, 2020 8:34 pm
Forum: Work, Gibbs Free Energy, Cell (Redox) Potentials
Topic: When to apply Pt into cell diagrams
Replies: 9
Views: 65

Re: When to apply Pt into cell diagrams

use Pt(s) when there's no metal conductor
by Diana Andrade_4F
Fri Feb 28, 2020 8:21 pm
Forum: Balancing Redox Reactions
Topic: Writing half reactions
Replies: 9
Views: 61

Re: Writing half reactions

Yes! It's best to keep oxidized molecules to the left and reduced molecules to the right, this is also stated in the textbook.
by Diana Andrade_4F
Fri Feb 28, 2020 8:17 pm
Forum: Balancing Redox Reactions
Topic: Test 2
Replies: 10
Views: 51

Re: Test 2

Test 2 will cover the rest of outline 4 (what wasn't on the midterm) and Outline 5 only. No kinetics!
by Diana Andrade_4F
Fri Feb 28, 2020 8:16 pm
Forum: Balancing Redox Reactions
Topic: How to tell if its being reduced or oxidized
Replies: 15
Views: 81

Re: How to tell if its being reduced or oxidized

You have to look at Mn only, and we see that it goes from 7+ to 2+, thus being reduced
by Diana Andrade_4F
Sat Feb 22, 2020 2:03 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Adding Inert Gas
Replies: 20
Views: 136

Re: Adding Inert Gas

Adding an inert gas doesn’t affect the equilibrium constant
by Diana Andrade_4F
Fri Feb 21, 2020 3:40 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Adiabatic systems
Replies: 11
Views: 61

Re: Adiabatic systems

Yes, ALWAYS! Thats because there is no heat transfer.
by Diana Andrade_4F
Fri Feb 21, 2020 3:36 pm
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: E
Replies: 5
Views: 20

Re: E

E will be positive if reaction is spontaneous!
by Diana Andrade_4F
Fri Feb 21, 2020 1:04 am
Forum: Balancing Redox Reactions
Topic: Reduction vs. oxidation
Replies: 29
Views: 123

Re: Reduction vs. oxidation

Reduction means gain of electron, it becomes more negative. While oxidation is the loss of electron, becomes more positive.
by Diana Andrade_4F
Fri Feb 21, 2020 1:02 am
Forum: Balancing Redox Reactions
Topic: Test 2 [ENDORSED]
Replies: 12
Views: 104

Re: Test 2 [ENDORSED]

Test 2 was moved to week 9 so we could have more time with the material! Also, it will include material after the midterm (outlines 4 and 5). It won't include kinetics.
by Diana Andrade_4F
Sat Feb 15, 2020 4:54 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: spontaneity
Replies: 34
Views: 225

Re: spontaneity

Definitely Gibbs Free energy (delta G)! If delta G is negative then the reaction is spontaneous, but if it’s positive it is not.
by Diana Andrade_4F
Sat Feb 15, 2020 4:52 pm
Forum: Third Law of Thermodynamics (For a Unique Ground State (W=1): S -> 0 as T -> 0) and Calculations Using Boltzmann Equation for Entropy
Topic: degeneracy W
Replies: 7
Views: 62

Re: degeneracy W

To find W, you can use the equation W=(P)^a
Where “P” is the number of possible positions and “a” is the number of atoms
by Diana Andrade_4F
Tue Feb 11, 2020 12:19 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Test 1 Problem 6
Replies: 2
Views: 41

Re: Test 1 Problem 6

Oh sure thing!

The pH of a 0.010 M solution of hydrofluoric acid is 2.63. What are Ka and percent ionization?
by Diana Andrade_4F
Mon Feb 10, 2020 10:42 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Test 1 Problem 6
Replies: 2
Views: 41

Test 1 Problem 6

Can someone explain to me how to solve problem 6 from test 1? Thank you!
by Diana Andrade_4F
Mon Feb 10, 2020 10:26 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: pKb to pOH
Replies: 2
Views: 24

pKb to pOH

How do you find pOH when only given pKb?
by Diana Andrade_4F
Fri Feb 07, 2020 9:06 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: state occupation of phases
Replies: 7
Views: 23

Re: state occupation of phases

Gasses have higher entropy, while solids and liquids have their molecules tightly packed. Gas molecules can be in any location, since they are not tightly packed, which is why they "occupy more space"
by Diana Andrade_4F
Fri Feb 07, 2020 8:58 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: closed vs isolated
Replies: 14
Views: 59

Re: closed vs isolated

A closed system is when a system can only transfer energy (like heat) with its surroundings, meanwhile an isolated system can't transfer anything with its surroundings.
by Diana Andrade_4F
Fri Feb 07, 2020 8:54 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: isolated system
Replies: 8
Views: 43

Re: isolated system

A reaction in a bomb calorimeter is considered an isolated system because the calorimeter is closed and isolated. This means that no energy and no matter is being transferred.
by Diana Andrade_4F
Fri Feb 07, 2020 8:46 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Isolated vs Closed [ENDORSED]
Replies: 34
Views: 235

Re: Isolated vs Closed [ENDORSED]

A closed system is when a system can only exchange energy (like heat) with its surroundings. Meanwhile, an isolated system is a system that can't exchange anything with its surroundings.
by Diana Andrade_4F
Thu Feb 06, 2020 11:47 pm
Forum: Administrative Questions and Class Announcements
Topic: Grading
Replies: 7
Views: 69

Grading

Can someone explain to me how the grading works for this class, I'm a bit confused. Thanks!
by Diana Andrade_4F
Thu Jan 30, 2020 8:57 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: adiabatic systems
Replies: 10
Views: 310

Re: adiabatic systems

Adiabatic means that there is no heat transfer
by Diana Andrade_4F
Thu Jan 30, 2020 8:52 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Endothermic vs Exothermic
Replies: 10
Views: 53

Re: Endothermic vs Exothermic

Yeah you are right. Positive q means reaction is endothermic since the system gained heat. Negative q means reaction is exothermic since heat is released.
by Diana Andrade_4F
Thu Jan 30, 2020 8:47 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: Units for temperature?
Replies: 11
Views: 44

Re: Units for temperature?

You can use either unit, but make sure you use the same units throughout the problem.
by Diana Andrade_4F
Thu Jan 30, 2020 8:42 pm
Forum: Thermodynamic Definitions (isochoric/isometric, isothermal, isobaric)
Topic: Qv vs Qp
Replies: 7
Views: 35

Re: Qv vs Qp

Qv is when there's constant volume while Qp is constant pressure
by Diana Andrade_4F
Thu Jan 30, 2020 5:39 pm
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: delta V & delta U
Replies: 1
Views: 14

delta V & delta U

Why is it that when delta V = 0, delta U = q?
by Diana Andrade_4F
Thu Jan 23, 2020 5:16 pm
Forum: Phase Changes & Related Calculations
Topic: removing heat from system
Replies: 6
Views: 261

Re: removing heat from system

Yeah, if a reaction is exothermic then temp will decrease. This is because the reaction is releasing heat (delta H is negative).
by Diana Andrade_4F
Thu Jan 23, 2020 5:02 pm
Forum: Student Social/Study Group
Topic: Midterm and Final Question
Replies: 18
Views: 172

Midterm and Final Question

will there be study guides for the midterm and final?
by Diana Andrade_4F
Thu Jan 23, 2020 4:34 pm
Forum: Ideal Gases
Topic: Kc vs Kp
Replies: 43
Views: 280

Re: Kc vs Kp

You use Kc when you are given a concentration, while Kp is used when given partial pressures. However, you can use Kp to find Kc if needed.
by Diana Andrade_4F
Thu Jan 23, 2020 4:24 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Exothermic vs. Endothermic reactions
Replies: 12
Views: 99

Re: Exothermic vs. Endothermic reactions

Yes, you should be able to determine if the reaction is exothermic or endothermic when given delta H.
by Diana Andrade_4F
Thu Jan 23, 2020 4:21 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: pKa/pKb and Ka/Kb
Replies: 5
Views: 30

pKa/pKb and Ka/Kb

What is the difference between pKa/pKb and Ka/Kb?
by Diana Andrade_4F
Fri Jan 17, 2020 5:28 pm
Forum: Ideal Gases
Topic: Partial Pressure
Replies: 8
Views: 55

Re: Partial Pressure

Each gas in a reaction has a partial pressure that all come together to make a whole pressure.
by Diana Andrade_4F
Thu Jan 16, 2020 10:57 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Heat
Replies: 3
Views: 16

Re: Heat

In an endothermic reaction, heat is a reactant. So, if temperature increases, reactants increases so it shifts to the right and favors Products. In an exothermic reaction, heat is a product. If temperature is increased, products increase, so it shifts to the left and Reactants are favored.
by Diana Andrade_4F
Thu Jan 16, 2020 10:20 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH
Replies: 2
Views: 32

pH

Why doesn't pH have units?
by Diana Andrade_4F
Thu Jan 16, 2020 10:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc & Kp
Replies: 12
Views: 66

Kc & Kp

How do you know when to use Kc or Kp when dealing with gasses? For example, in problem 5I.17 we use Kc instead of Kp, why?
by Diana Andrade_4F
Thu Jan 16, 2020 10:13 pm
Forum: Phase Changes & Related Calculations
Topic: Autoprotolysis
Replies: 15
Views: 103

Re: Autoprotolysis

Autoprotolysis is when two identical molecules transfer protons.
by Diana Andrade_4F
Thu Jan 09, 2020 10:23 pm
Forum: Ideal Gases
Topic: K value
Replies: 14
Views: 79

Re: K value

if K < 10^-3, then there are more reactants at equilibrium; this means that the equilibrium sits to the left.
if K > 10^3, then there are products at equilibrium; so equilibrium sits ti the right.
if K=1, the concentration of products and reactants are equal, so they have same stabilities.
by Diana Andrade_4F
Thu Jan 09, 2020 10:08 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Q vs K
Replies: 8
Views: 58

Re: Q vs K

K is an equilibrium constant, while Q is a reaction quotient. K is found when the reaction is at equilibrium, but Q can be calculated at any time during the reaction. You can compare the reaction quotient, Q, to the equilibrium constant, K, to determine the direction of the reaction.
by Diana Andrade_4F
Thu Jan 09, 2020 7:53 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Why is K unitless?
Replies: 10
Views: 52

Re: Why is K unitless?

K is just a ratio of products/reactants, so there are no units. Also, when calculating K, the units just cancel out.
by Diana Andrade_4F
Thu Jan 09, 2020 7:51 pm
Forum: Ideal Gases
Topic: Understanding Q
Replies: 13
Views: 87

Re: Understanding Q

Yes, you don't include solids and liquids, only whatever is in gaseous/aqueous states when calculating Q.
by Diana Andrade_4F
Thu Jan 09, 2020 4:14 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Textbook 5H.1 Part 1
Replies: 4
Views: 26

Textbook 5H.1 Part 1

For this part of the problem, why do we get the square root of 41?

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