Search found 93 matches

by Agustina Santa Cruz 2F
Sun Feb 28, 2021 7:13 pm
Forum: Balancing Redox Reactions
Topic: sapling #19
Replies: 6
Views: 16

Re: sapling #19

I got the same thing but add in the phases and I didn't use parentheses in the product side, IDK if I was supposed to but it said it was right: 4Fe(s)+3O2(g)+6H2O(l)⟶2Fe2O3∙3H2O(s)
by Agustina Santa Cruz 2F
Sun Feb 28, 2021 7:12 pm
Forum: Student Social/Study Group
Topic: Sapling Weeks 7-8 Homework Question
Replies: 2
Views: 10

Re: Sapling Weeks 7-8 Homework Question

Shorthand notation should be: Pb (s), PbCl2 (s), Cl- (aq), Cl-(aq), AgCl(s), Ag(s)
by Agustina Santa Cruz 2F
Sun Feb 28, 2021 7:07 pm
Forum: Balancing Redox Reactions
Topic: Sapling Week 7/8 Question 3
Replies: 5
Views: 38

Re: Sapling Week 7/8 Question 3

Make sure you put phases in and the correct arrow (irreversible I think)
by Agustina Santa Cruz 2F
Sun Feb 28, 2021 5:44 pm
Forum: Balancing Redox Reactions
Topic: reversible redox reaction
Replies: 3
Views: 9

reversible redox reaction

Can a redox reaction be reversible? How do we know if it is?
by Agustina Santa Cruz 2F
Sun Feb 28, 2021 5:43 pm
Forum: Balancing Redox Reactions
Topic: states of matter
Replies: 52
Views: 109

states of matter

Hi for Sapling Problems in week 7 and 8 I keep getting the balancing redox reaction problems wrong but feel like I'm doing it right. Can states of matter cause an equation on Sapling to be wrong?
by Agustina Santa Cruz 2F
Sun Feb 21, 2021 6:35 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Boiling point
Replies: 6
Views: 28

Boiling point

Is boiling point always found at equilibrium (deltaG=0)? If so, why?
by Agustina Santa Cruz 2F
Sun Feb 21, 2021 6:32 pm
Forum: Calculating Work of Expansion
Topic: adiabatic processes
Replies: 18
Views: 36

adiabatic processes

In adiabatic processes is w=0?
by Agustina Santa Cruz 2F
Sun Feb 21, 2021 6:30 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: calculating H through bond enthalpies
Replies: 3
Views: 12

calculating H through bond enthalpies

Why is there an added negative sign on the side of the products when using bond enthalpies to calculate total reaction enthalpy?
by Agustina Santa Cruz 2F
Sun Feb 21, 2021 6:27 pm
Forum: Entropy Changes Due to Changes in Volume and Temperature
Topic: Hfus
Replies: 9
Views: 22

Hfus

How do we know when to use Hfusion?
by Agustina Santa Cruz 2F
Sun Feb 21, 2021 6:21 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: state functions
Replies: 6
Views: 16

state functions

Why are heat and work not state functions? I'm having a little trouble understanding the definition of state functions.
by Agustina Santa Cruz 2F
Sun Feb 14, 2021 9:44 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: thermodynamic reaction quotient
Replies: 4
Views: 10

thermodynamic reaction quotient

When calculating Q,, I know its (partial pressure of products/ partial pressure of reactants) and to use molar coefficients as exponents but do you multiply or add the partial pressures of individual molecules in the numerator (or denominator)? Like if there's multiple reactants or products.
by Agustina Santa Cruz 2F
Sun Feb 14, 2021 9:41 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: values
Replies: 3
Views: 34

values

Will entropy, enthalpy, and deltaGf values of specific molecules from the sapling charts be given on tests?
by Agustina Santa Cruz 2F
Sun Feb 14, 2021 9:39 pm
Forum: Gibbs Free Energy Concepts and Calculations
Topic: units
Replies: 5
Views: 39

units

Are the standard units for thermodynamics questions always volume (L), temperature (K), energy (KJ)? Am I missing one?
by Agustina Santa Cruz 2F
Sun Feb 14, 2021 5:24 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: qrev vs q
Replies: 19
Views: 56

qrev vs q

What is the difference between qrev vs just regular q? When do we use each?
by Agustina Santa Cruz 2F
Sun Feb 14, 2021 5:24 pm
Forum: Concepts & Calculations Using Second Law of Thermodynamics
Topic: qrev vs q
Replies: 8
Views: 23

qrev vs q

What is the difference between qrev vs just regular q? When do we use each?
by Agustina Santa Cruz 2F
Sun Feb 07, 2021 11:57 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: sapling 20
Replies: 3
Views: 21

sapling 20

Hi does anyone know how to do this one? A 0.825 mol sample of CO2(g) initially at 298 K and 1.00 atm is held at constant volume while enough heat is applied to raise the temperature of the gas by 18.7 K. Assuming ideal gas behavior, calculate the amount of heat (q) in joules required to affect this ...
by Agustina Santa Cruz 2F
Sun Feb 07, 2021 11:56 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: sapling 18
Replies: 1
Views: 14

sapling 18

Hi for 18 I was able to get deltaU which was 112.4 but couldn't find q. A 0.825 mol sample of Xe(g), initially at 298 K and 1.00 atm, is held at constant pressure while enough heat is applied to raise the temperature of the gas by 10.9 K. Calculate the amount of heat q required to bring about this t...
by Agustina Santa Cruz 2F
Sun Feb 07, 2021 11:46 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: sapling 19
Replies: 1
Views: 18

sapling 19

Hi can anyone help on this one? A constant‑volume calorimeter was calibrated by carrying out a reaction known to release 1.05 kJ of heat in 0.700 L of solution in the calorimeter (q=−1.05 kJ) , resulting in a temperature rise of 2.19 ∘C . In a subsequent experiment, 350.0 mL of 0.30 M HClO2(aq) and ...
by Agustina Santa Cruz 2F
Sun Feb 07, 2021 10:26 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: Sapling 10 week 4
Replies: 3
Views: 24

Sapling 10 week 4

An ice cube with a mass of 46.8 g at 0.0 ∘C is added to a glass containing 401 g of water at 45.0 ∘C . Determine the final temperature of the system at equilibrium. The specific heat capacity of water, Cs , is 4.184 J/g⋅∘C , and the standard enthalpy of fusion, ΔH∘fus , of water is 6.01×103 J/mol . ...
by Agustina Santa Cruz 2F
Sun Feb 07, 2021 9:58 pm
Forum: Heat Capacities, Calorimeters & Calorimetry Calculations
Topic: -qlost=qabsorbed
Replies: 4
Views: 15

-qlost=qabsorbed

Hi, for saplng 9 week 4, we put a (-) in front of the side that lost heat. However, in sapling 10, no negative is inserted for the water that got cooled from the ice cube. Can anyone explain why?
by Agustina Santa Cruz 2F
Thu Jan 28, 2021 9:50 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: lecture method 3 equation
Replies: 3
Views: 42

lecture method 3 equation

Hi, why did Dr. Lavelle leave out 2 H2O (l) from the method 3 class example but not 2 O2 (g) on the reactants side? Aren't they both at standard states? Also, when do we have to take into account the change in enthalpy of vaporization or any of phase change? The professor said that if H2O were to ha...
by Agustina Santa Cruz 2F
Thu Jan 28, 2021 9:37 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Sapling week 3 #6
Replies: 12
Views: 106

Sapling week 3 #6

C(g)+4H(g)⟶CH4(g)

enthalpy of formation of CH4(g)

4×bond energy of C−H

enthalpy of combustion of C

−4×bond energy of C−H

Why is the answer -4 x bond energy rather than 4 x bond energy?
by Agustina Santa Cruz 2F
Thu Jan 28, 2021 8:14 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Enthalpies
Replies: 2
Views: 18

Enthalpies

Will the enthalpies be given on the test for molecules? Bc in the lecture he says to look them up but obviously on the tests we can't do that. (this is in regards to the enthalpies used in methods 2 and 3)
by Agustina Santa Cruz 2F
Mon Jan 25, 2021 4:36 pm
Forum: Phase Changes & Related Calculations
Topic: midterm 1
Replies: 11
Views: 117

midterm 1

Hi, does someone know if the cutoff for the midterm material on sapling question 10 from week 3/4? B/c the exam is only on week 1-3 right?
by Agustina Santa Cruz 2F
Mon Jan 25, 2021 4:33 pm
Forum: Phase Changes & Related Calculations
Topic: heating curve
Replies: 8
Views: 45

heating curve

Hi, can someone explain the heating curve and how that applies to why steam causes severe burns? Dr. Lavelle explained in one of his lectures but I'm still a little confused.
by Agustina Santa Cruz 2F
Sun Jan 24, 2021 8:49 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: pKa
Replies: 14
Views: 58

Re: pKa

p before a constant or value usually means taking the log or -log of it. In this cause pKa IS -log(Ka) which is your equilibrium constant of the dissociation recation of an acid.
by Agustina Santa Cruz 2F
Sun Jan 24, 2021 8:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: X Approximations
Replies: 23
Views: 106

Re: X Approximations

Usually if K is smaller than 10^-4, you can approximate and take it out of denominator so that you don't have to use the quadratic formula.
by Agustina Santa Cruz 2F
Sun Jan 24, 2021 8:29 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Sapling Week 2 #7
Replies: 8
Views: 52

Sapling Week 2 #7

HClO is a weak acid ( Ka=4.0×10−8 ) and so the salt NaClO acts as a weak base. What is the pH of a solution that is 0.024 M in NaClO at 25 °C?

Why does the ICE table only include ClO- and HClO and OH-. What happened to the NaClO?
by Agustina Santa Cruz 2F
Sun Jan 24, 2021 8:18 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: acids and bases
Replies: 4
Views: 44

acids and bases

Hi, I know this is primarily a 14A concept, but what are some tips that help you identify whether a substance is neutral, basic, or acidic?
by Agustina Santa Cruz 2F
Sun Jan 24, 2021 7:15 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: approximating
Replies: 10
Views: 45

approximating

Hi, after creating the ICE table oftentimes we see that x will be too small to make a difference, therefore, we can approximate. However, why do we only take one x out from the denominator and not from the x^2 in the numerator?
by Agustina Santa Cruz 2F
Sun Jan 17, 2021 5:55 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: endothermic vs exothermic
Replies: 16
Views: 59

endothermic vs exothermic

How can you tell if a reaction is endothermic or exothermic?
by Agustina Santa Cruz 2F
Sun Jan 17, 2021 4:25 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Week 1 Sapling 5
Replies: 4
Views: 57

Week 1 Sapling 5

Consider the reaction of NH3 and I2 to give N2 and HI. 2NH3(g)+3I2(g)↽−−⇀N2(g)+6HI(g)K Using two or more of the given equations, determine the equilibrium constant, K , for the reaction of NH3 with I2. H2 (g) +I2 (g) >>> 2HI (g) Ka = 160 I2 (g) >>>2I (g) Kb = 2.1 * 10-3 N2 (g) + 3H2 (g) >>>2NH3 (g) ...
by Agustina Santa Cruz 2F
Sun Jan 17, 2021 3:55 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Week 1 Sapling 3
Replies: 11
Views: 69

Week 1 Sapling 3

At a certain temperature, the equilibrium constant, Kc, for this reaction is 53.3. H2(g)+I2(g)↽−−⇀2HI(g)Kc=53.3 At this temperature, 0.700 mol H2 and 0.700 mol I2 were placed in a 1.00 L container to react. What concentration of HI is present at equilibrium? Would you use the quadratic formula for: ...
by Agustina Santa Cruz 2F
Sun Jan 17, 2021 3:02 pm
Forum: Ideal Gases
Topic: R Value
Replies: 17
Views: 89

R Value

Hi, I've seen a lot of different posts about the R Value in the Ideal Gas Law. For tests, do we use 8.206 x 10^-2?
by Agustina Santa Cruz 2F
Sun Jan 17, 2021 2:58 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: shifts left or right
Replies: 23
Views: 95

shifts left or right

Hi, I know that when Q<K then its a forward reaction and it shift right. It shifts left when it is the opposite. But, what exactly does this shift indicate? I know it's important to know whether it is a forward or reverse reaction but what is the importance of identifying the shift?
by Agustina Santa Cruz 2F
Sun Jan 10, 2021 7:57 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: K vs P
Replies: 6
Views: 52

K vs P

When should you calculate P instead of K? I initially thought P was only for gases but then I think I saw K be calculated for a homogenous gas reaction.
by Agustina Santa Cruz 2F
Sun Jan 10, 2021 7:55 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: reaction quotient
Replies: 6
Views: 34

reaction quotient

I know how to calculate reaction quotient but what does reaction quotient actually define?
by Agustina Santa Cruz 2F
Sun Jan 10, 2021 7:54 pm
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: adding heat
Replies: 15
Views: 102

adding heat

Why is heating endothermic reactions more favorable?
by Agustina Santa Cruz 2F
Sat Jan 09, 2021 4:14 pm
Forum: Ideal Gases
Topic: gas law vs equlibrium constant vs quotient constant
Replies: 3
Views: 61

gas law vs equlibrium constant vs quotient constant

Hi! I understand how to use the ideal gas law, find equilibrium constant, and quotient constant but can someone summarize WHEN each should be used? I'm especially having trouble understanding when to apply the ideal gas law.
by Agustina Santa Cruz 2F
Wed Jan 06, 2021 3:47 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: molar concentrations
Replies: 5
Views: 35

molar concentrations

Will the molar concentrations always be given in problems where we need to find Kc? If not, how do you calculate concentration?
by Agustina Santa Cruz 2F
Wed Dec 16, 2020 5:27 pm
Forum: Student Social/Study Group
Topic: Final Exam
Replies: 49
Views: 355

Re: Final Exam

Ya, I started on the problems I knew so that I would get points for those for sure. The others could've been wrong so if I ran out of time it probably would have the same effect on my grade. Wish there had been more time too!
by Agustina Santa Cruz 2F
Wed Dec 16, 2020 5:26 pm
Forum: Student Social/Study Group
Topic: Plans for Relaxing After Finals
Replies: 98
Views: 573

Re: Plans for Relaxing After Finals

I'm going to my cabin in the Sierra Nevadas for some isolation and relaxation. Hopefully there's snow this year!
by Agustina Santa Cruz 2F
Wed Dec 16, 2020 5:25 pm
Forum: Student Social/Study Group
Topic: Course Evals
Replies: 18
Views: 137

Re: Course Evals

I don't think they are mandatory or graded so don't stress. You don't have to do them but it helps teachers prep and make changes for next quarter/year.
by Agustina Santa Cruz 2F
Wed Dec 16, 2020 5:23 pm
Forum: Student Social/Study Group
Topic: Words of encouragement
Replies: 13
Views: 109

Re: Words of encouragement

So proud of everyone! Don't be too hard on yourselves as we start getting final grades back. This semester was extra challenging and we should take that into account. Studying in a home environment, it's difficult to stay motivated. Pat yourself on the back for getting through it!
by Agustina Santa Cruz 2F
Wed Dec 16, 2020 5:22 pm
Forum: Administrative Questions and Class Announcements
Topic: 14B Enrollment [ENDORSED]
Replies: 31
Views: 1473

Re: 14B Enrollment [ENDORSED]

Thank you Professor Lavelle for a great semester! See you in Chem 14B!
by Agustina Santa Cruz 2F
Wed Dec 16, 2020 5:21 pm
Forum: Student Social/Study Group
Topic: Final Jitters
Replies: 251
Views: 36391

Re: Final Jitters

Congrats to everyone for completing this course! You should be very proud of yourselves given the circumstances! Don't be too hard on yourselves, it's immensely hard to learn from home so cut yourself some slack & give yourself some credit!
by Agustina Santa Cruz 2F
Wed Dec 16, 2020 5:19 pm
Forum: Student Social/Study Group
Topic: grade calculation
Replies: 12
Views: 125

grade calculation

Is there any grade calculator available for this course?
by Agustina Santa Cruz 2F
Sun Dec 06, 2020 9:56 pm
Forum: Student Social/Study Group
Topic: finals
Replies: 4
Views: 60

finals

How are you guys studying for finals? Do you start by reviewing old material or the new material? Also how do you simultaneously learn this week's topics and also review for finals without getting overwhelmed?
by Agustina Santa Cruz 2F
Sun Dec 06, 2020 9:51 pm
Forum: Bronsted Acids & Bases
Topic: H2PO4- amphoteric
Replies: 2
Views: 23

H2PO4- amphoteric

How is H2PO4- amphoteric? Amphoteric means that is can be both an acid or a base right? Therefore, this molecule should be able to accept protons and donate?
by Agustina Santa Cruz 2F
Sun Dec 06, 2020 9:49 pm
Forum: Conjugate Acids & Bases
Topic: NH3
Replies: 4
Views: 27

NH3

How is NH3 a base? Aren't acids the compounds containing H? and bases contain OH?
by Agustina Santa Cruz 2F
Sun Dec 06, 2020 9:48 pm
Forum: Conjugate Acids & Bases
Topic: HSO4- conjugate base
Replies: 4
Views: 42

HSO4- conjugate base

How does the conjugate base of HSO4 end up being SO42-. B/c wouldn't that be taking an H+ away? I thought a base was a proton acceptor.
by Agustina Santa Cruz 2F
Sun Dec 06, 2020 9:45 pm
Forum: Lewis Acids & Bases
Topic: lewis vs bronsted
Replies: 10
Views: 70

lewis vs bronsted

What is the difference between a lewis acid/base and a bronsted acid/base?
by Agustina Santa Cruz 2F
Sun Nov 29, 2020 9:57 pm
Forum: Electronegativity
Topic: Be vs Cl
Replies: 13
Views: 117

Re: Be vs Cl

Be is higher in electronegativity because the periodic trend for increasing electronegativity is going right and up.
by Agustina Santa Cruz 2F
Sun Nov 29, 2020 9:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: AsO43-
Replies: 9
Views: 81

AsO43-

How is AsO43- a nonpolar molecule if it has a charge?
by Agustina Santa Cruz 2F
Sun Nov 29, 2020 9:46 pm
Forum: Hybridization
Topic: PBr5
Replies: 6
Views: 45

PBr5

Why would the hybridization of PBr5 be sp3d?
by Agustina Santa Cruz 2F
Sun Nov 29, 2020 9:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: trigonal bipyramidal
Replies: 5
Views: 43

trigonal bipyramidal

How do you know when the bond angle is 120 versus 90 for trigonal bipyramidal?
by Agustina Santa Cruz 2F
Sun Nov 29, 2020 8:14 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: ions
Replies: 8
Views: 86

ions

If atoms in a molecule have a negative or positive charge, how would that affect the VSEPR theory?
by Agustina Santa Cruz 2F
Fri Nov 20, 2020 3:03 pm
Forum: Dipole Moments
Topic: higher dipole moment sapling #10
Replies: 5
Views: 60

higher dipole moment sapling #10

Sapling #10 Which molecule should have higher dipole moment, and why? a. COF2 because it contains more F atoms. b. COFH because the polar bonds in COF 2 nearly cancel each other out. c. COF2 because it contains more lone pairs. I'm confused as to why the answer is B. You'd think that COF2 has a high...
by Agustina Santa Cruz 2F
Fri Nov 20, 2020 2:58 pm
Forum: Dipole Moments
Topic: Polarity
Replies: 30
Views: 165

Polarity

How can a molecule be made up of polar bonds but not be polar as whole molecule?
by Agustina Santa Cruz 2F
Fri Nov 20, 2020 2:57 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: determining molecular shape
Replies: 10
Views: 89

determining molecular shape

How is Co2 not polar but So2 is? Since they both have similar structures.
by Agustina Santa Cruz 2F
Fri Nov 20, 2020 2:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear shape
Replies: 7
Views: 57

Linear shape

How is NO2- not a linear molecular shape?
by Agustina Santa Cruz 2F
Fri Nov 20, 2020 2:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: axial and equatorial atoms
Replies: 2
Views: 36

axial and equatorial atoms

I'm having some trouble identifying axial and equatorial atoms. What's the difference? Because I feel like if I rotate the molecule, the perspective changes.
by Agustina Santa Cruz 2F
Sun Nov 15, 2020 8:37 pm
Forum: Resonance Structures
Topic: resonance structures
Replies: 10
Views: 49

resonance structures

How do you know which resonance structure contributes most heavily to the true structure of the molecule?
by Agustina Santa Cruz 2F
Sun Nov 15, 2020 8:01 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Sapling #20
Replies: 12
Views: 97

Re: Sapling #20

Sukhkiran_Kaur_3F wrote:Hydrogen bonds are not present in CH3CHO because none of the hydrogens are bonded to the oxygen.

How do you know the H isn't bonded to the electronegative O, thus creating a hydrogen bond? Would you have to draw the lewis structre out?
by Agustina Santa Cruz 2F
Sun Nov 15, 2020 7:45 pm
Forum: Electronegativity
Topic: polar vs nonpolar
Replies: 19
Views: 116

polar vs nonpolar

What does the minimum numerical difference in electronegativity have to be for a molecule to be considered polar?
by Agustina Santa Cruz 2F
Sun Nov 15, 2020 6:39 pm
Forum: Ionic & Covalent Bonds
Topic: bond lengths
Replies: 9
Views: 82

bond lengths

Why are double bonds shorter than single bonds?
by Agustina Santa Cruz 2F
Sun Nov 15, 2020 6:10 pm
Forum: Octet Exceptions
Topic: octet rule
Replies: 8
Views: 80

octet rule

Why does Cl get 18 octet electrons?
by Agustina Santa Cruz 2F
Sun Nov 08, 2020 4:41 pm
Forum: Bond Lengths & Energies
Topic: bond lengths
Replies: 9
Views: 37

bond lengths

How do you know which bond lengths are longer than others?
by Agustina Santa Cruz 2F
Sun Nov 08, 2020 4:36 pm
Forum: Lewis Structures
Topic: octet rule
Replies: 7
Views: 58

octet rule

How do we know if the octet rule should be followed or not? When is it allowed to be broken?
by Agustina Santa Cruz 2F
Sun Nov 08, 2020 4:18 pm
Forum: Lewis Acids & Bases
Topic: Acids and Bases
Replies: 3
Views: 20

Acids and Bases

Can a lewis acid only react with a Lewis base?
by Agustina Santa Cruz 2F
Thu Nov 05, 2020 9:33 pm
Forum: Electronegativity
Topic: polyatomic ions
Replies: 4
Views: 33

polyatomic ions

How do you know which atom is negative or positive in a polyatomic ion? I was looking for an extra electron when I saw a resonance structure of carbamate and the oxygen was negative, but it had the correct number. It was double bonded to a positive nitrogen (with four bonds) so does that automatical...
by Agustina Santa Cruz 2F
Thu Nov 05, 2020 9:27 pm
Forum: Ionic & Covalent Bonds
Topic: resonance structures
Replies: 2
Views: 22

resonance structures

Can quadruple bonds be formed in resonance structures?
by Agustina Santa Cruz 2F
Sun Nov 01, 2020 5:39 pm
Forum: Properties of Electrons
Topic: ion radius size
Replies: 3
Views: 45

ion radius size

What is the trend for ion radius size?
by Agustina Santa Cruz 2F
Sun Nov 01, 2020 5:36 pm
Forum: Bond Lengths & Energies
Topic: ionization energy
Replies: 6
Views: 92

ionization energy

Why does oxygen have a lower first ionization energy than both nitrogen and flourine?

This was one of the sapling questions, and I completed it, but I am still a little confused. Can anyone clear this up please?
by Agustina Santa Cruz 2F
Wed Oct 28, 2020 2:42 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: ground state electron configuration
Replies: 2
Views: 23

ground state electron configuration

What is the difference between excited and ground state electron configuration?
by Agustina Santa Cruz 2F
Wed Oct 28, 2020 12:54 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: How many electrons in an atom
Replies: 1
Views: 38

How many electrons in an atom

How many electrons in an atom could have these sets of quantum numbers?
n=2
n=4, l=3
n=7, l=2, ml= -1

Hi, could someone explain this problem please? I'm so confused. I know that L=0,1, 2, 3 is correspondant with s, p, d, and f. and that s has one orbital, p=3, d=5, and f= 7.
by Agustina Santa Cruz 2F
Wed Oct 28, 2020 12:17 am
Forum: Properties of Light
Topic: Sapling Week 3 Problem 8
Replies: 3
Views: 82

Re: Sapling Week 3 Problem 8

Yes for this problem the ending energy level would be n=2, in the Balmer series. What equation did you plug n and the wavelength into? If you're using Rydberg's equation, it is v = R (1/n1^2 - 1/n2^2), where n1 is the final energy level and n2 is the initial level. Convert wavelength to meters. You...
by Agustina Santa Cruz 2F
Wed Oct 28, 2020 12:03 am
Forum: SI Units, Unit Conversions
Topic: Angstrom
Replies: 6
Views: 69

Angstrom

I'm a little confused on converting units still. I know 1 Angstrom is 10^-10m. But if I have 6.001x10^-7 and I multiply that by 10^-10 on my calculator, I get 6.001x10^-17 when the answer should be 6001 angstroms I think. Any ideas?
by Agustina Santa Cruz 2F
Tue Oct 27, 2020 11:01 pm
Forum: Properties of Light
Topic: Sapling Week 3 Problem 8
Replies: 3
Views: 82

Sapling Week 3 Problem 8

A blue line is observed at 486.1 nm in the spectrum of atomic hydrogen. Determine the values of n for the beginning and ending energy levels of the electron during the emission of energy that leads to this spectral line. I've seen a lot of these but can't seem to really grasp the answer. Since it is...
by Agustina Santa Cruz 2F
Tue Oct 27, 2020 10:54 pm
Forum: Properties of Light
Topic: rydberg's equation
Replies: 2
Views: 39

rydberg's equation

On the equation sheet, rydberg's equation is v= R(1/n1^2-1/n2^2) , but online, it's usually 1/wavelength= R(1/n1^2-1/n2^2). Which one is better to use and why do they differ?
by Agustina Santa Cruz 2F
Tue Oct 27, 2020 10:53 pm
Forum: Properties of Light
Topic: rydberg's constant
Replies: 11
Views: 98

rydberg's constant

On the equation sheet, rydberg's constant is 3.28984 x10^15 Hz, but online, it's usually 1.097x10^7 m. Which one is better to use and why do they differ?
by Agustina Santa Cruz 2F
Sun Oct 18, 2020 8:14 pm
Forum: Significant Figures
Topic: rounding during equations
Replies: 14
Views: 111

Re: rounding during equations

I recommend rounding at the end to get the most accurate result and sig figs.
by Agustina Santa Cruz 2F
Sun Oct 18, 2020 8:13 pm
Forum: SI Units, Unit Conversions
Topic: studying tactics
Replies: 8
Views: 35

studying tactics

Hey guys what are the most productive studying tactics to study for the midterm? Do you recommend mostly book problems and step up sessions?
by Agustina Santa Cruz 2F
Sun Oct 18, 2020 8:05 pm
Forum: Student Social/Study Group
Topic: How are you studying?
Replies: 203
Views: 1402

Re: How are you studying?

Hey, I think a key step in memorizing information from lectures is to write a summary at the end and then try to recite it later that day so the information stays fresh. Do chem everyday even if it's just for 15-20 minutes. Textbook problems are good to get a feel for similar questions on the test a...
by Agustina Santa Cruz 2F
Sun Oct 18, 2020 7:46 pm
Forum: SI Units, Unit Conversions
Topic: unit conversions
Replies: 24
Views: 286

unit conversions

When converting units do you just multiply by 10^x given number or is there a different way? For example if I convert centi to giga, I multiply the number I'm converting by 10^9 and leave it in scientific notation?
by Agustina Santa Cruz 2F
Sun Oct 18, 2020 7:42 pm
Forum: Significant Figures
Topic: sig fig
Replies: 20
Views: 188

sig fig

Do you guys recommend changing to the correct numbers of sig figs in the middle of an equation or when you have the final result? Also, will we get marked down if sig fig numbers of final result don't match the amount given?
by Agustina Santa Cruz 2F
Sun Oct 18, 2020 7:29 pm
Forum: Significant Figures
Topic: Sig Figs and Zeroes
Replies: 5
Views: 56

Re: Sig Figs and Zeroes

Hi! Basically the rules for significant figures are: 1) non-zero numbers are always significant 2) any zeros between non-zero numbers are significant 3) a final zero in the decimal portion of a number is significant (ex. 111.900) 6 sigfigs * zeros after a decimal but before a non-zero don't count th...
by Agustina Santa Cruz 2F
Sun Oct 11, 2020 6:49 pm
Forum: Significant Figures
Topic: Sapling #4
Replies: 10
Views: 71

Re: Sapling #4

Hi Adam! Yes, I think any number after a decimal counts, even zeros!
by Agustina Santa Cruz 2F
Sun Oct 11, 2020 6:43 pm
Forum: Limiting Reactant Calculations
Topic: Help finding limiting reactant
Replies: 4
Views: 73

Help finding limiting reactant

Balance the reaction for the combustion of aspartame, an artificial sweetener (294.30g/mol): C14H18N2O5(s) + O2(g) -> CO2(g) + H2O(l) + N2(g) If you were to react exactly 2.00g O2 with 2.00g aspartame, what is the limiting reactant and the theoretical yield of liquid water? If the true yield is 0.05...
by Agustina Santa Cruz 2F
Sun Oct 11, 2020 6:32 pm
Forum: Empirical & Molecular Formulas
Topic: Sampling #9
Replies: 7
Views: 66

Re: Sampling #9

Hi! I had trouble with this one as well at first. 1) identify molar mass of CO2 and the given mass in grams. then find the mass of carbon alone. (grams/molar mass of CO2 x molar mass of carbon) This answer tells you how many grams of carbon are in one gram of the compound. Therefore, you can find th...
by Agustina Santa Cruz 2F
Sun Oct 11, 2020 6:14 pm
Forum: Molarity, Solutions, Dilutions
Topic: Sapling HW #6
Replies: 8
Views: 82

Re: Sapling HW #6

Hi! I was having the same issue. I think the molar mass that you used at the beginning was wrong. 187.56 is what google says but if you add all of them up separately you get 125.55. Try that?
by Agustina Santa Cruz 2F
Sun Oct 11, 2020 6:04 pm
Forum: Significant Figures
Topic: Sapling #4
Replies: 10
Views: 71

Re: Sapling #4

Hi! Basically the rules for significant figures are: 1) non-zero numbers are always significant 2) any zeros between non-zero numbers are significant 3) a final zero in the decimal portion of a number is significant (ex. 111.900) 6 sigfigs * zeros after a decimal but before a non-zero don't count th...

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