Search found 67 matches

by Lorraine Jiang 2C
Thu Jan 14, 2021 12:17 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Changing pressure by adding gas
Replies: 12
Views: 35

Re: Changing pressure by adding gas

Hi! So basically the equilibrium constant of a reaction with gases only shifts when there is a change of volume. Adding a gas (inert gas specifically) will not change the volume of the reaction environment as the inert gas will not react with the reactants nor the products. So the equilibrium consta...
by Lorraine Jiang 2C
Thu Jan 14, 2021 12:13 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: q vs k
Replies: 20
Views: 81

Re: q vs k

Hi! The reaction quotient basically represents the concentration of production to reactant at any given time in the reaction. However, K specifically implies the ratio at equilibrium.

Hope it helps!
by Lorraine Jiang 2C
Thu Jan 14, 2021 12:12 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Pressure Rule
Replies: 12
Views: 141

Re: Pressure Rule

Hi! So only gases are affected when there is a change in pressure so I think we don’t look at solids and liquids and we only look at gases in the reaction.

Hope it helps!
by Lorraine Jiang 2C
Thu Jan 14, 2021 12:11 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: adding heat
Replies: 14
Views: 41

Re: adding heat

Hi! An endothermic reaction means that it requires energy. By increasing the temperature of the reaction environment, we are helping the reactants to overcome the activation energy so the equilibrium will shift to the product side.

Hope it helps!
by Lorraine Jiang 2C
Thu Jan 14, 2021 12:09 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Increase in Pressure
Replies: 13
Views: 28

Re: Increase in Pressure

Hi! I believe increasing/decreasing pressure in a reaction system only has an effect on gases.

Hope it helps!
by Lorraine Jiang 2C
Fri Jan 08, 2021 6:25 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: dobule arrows
Replies: 6
Views: 49

Re: dobule arrows

Hi! I think the double arrow just highlights that value A is definitely smaller/larger than value B.

Hope it helps!
by Lorraine Jiang 2C
Fri Jan 08, 2021 6:20 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Gas Constant (R)
Replies: 12
Views: 44

Re: Gas Constant (R)

I think for this class we can use 8.314 J·K^-1·mol^-1.

Hope it helps!
by Lorraine Jiang 2C
Fri Jan 08, 2021 6:19 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Kc
Replies: 11
Views: 35

Re: Kc

Yep! I think we always use molarity to calculate Kc. For partial pressure, I think the same logic applies to Kp although I didn't see much examples on this topic.

Hope it helps!
by Lorraine Jiang 2C
Fri Jan 08, 2021 6:17 am
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Preset values of K
Replies: 5
Views: 36

Re: Preset values of K

Hi! I think the equilibrium constant is only temperature-dependent. I have linked a website that helped me when I was studying equilibrium constants. https://chem.libretexts.org/Bookshelves/Physical_and_Theoretical_Chemistry_Textbook_Maps/Supplemental_Modules_(Physical_and_Theoretical_Chemistry)/Equ...
by Lorraine Jiang 2C
Fri Jan 08, 2021 6:15 am
Forum: Ideal Gases
Topic: Kc for Gases
Replies: 11
Views: 54

Re: Kc for Gases

Hi! Basically, both Kc and Kp are values for chemical dynamic equilibrium. However, we use Kp when the reaction is in gas phase, and we use Kc when the reaction is in the aqueous phase.
by Lorraine Jiang 2C
Sat Dec 12, 2020 12:53 am
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Sapling Week 10 #13
Replies: 7
Views: 63

Re: Sapling Week 10 #13

Hi! For this question, you only need to consider the pKa of the species and the pH of the condition. For example, if pH is higher than the pKa, then acid will deprotonate and it will become charged.

Hope it helps!
by Lorraine Jiang 2C
Sat Dec 12, 2020 12:26 am
Forum: Conjugate Acids & Bases
Topic: Amphoteric
Replies: 11
Views: 84

Re: Amphoteric

Hi! I think professor Lavelle mentioned in the lecture that the amphoteric compounds mostly line up with the metalloids in the periodic table. Some examples are H2O and Al2O3.

Hope it helps!
by Lorraine Jiang 2C
Sat Dec 12, 2020 12:20 am
Forum: Polyprotic Acids & Bases
Topic: Calculating Ka
Replies: 9
Views: 74

Re: Calculating Ka

Hi! The formula for Ka will be [A-][H3O+]/[HA] so that is the concentration of the anion multiplies the concentration of the H+ ion divided by the concentration of the acid.

Hope it helps!
by Lorraine Jiang 2C
Sat Dec 12, 2020 12:18 am
Forum: Calculating the pH of Salt Solutions
Topic: Deciding which part of the salt affects pH
Replies: 4
Views: 16

Re: Deciding which part of the salt affects pH

Hi! I agree with the posts above, so basically you should consider the general formula of the salt first. If the salt contains a cation that is favorable to lose H+ when dissolved, then we know that the salt is acidic. If the cation is from group1 or 2, and the anion is capable of getting another H+...
by Lorraine Jiang 2C
Sat Dec 12, 2020 12:15 am
Forum: Calculating the pH of Salt Solutions
Topic: pH formula?
Replies: 46
Views: 922

Re: pH formula?

Hi! The formula to calculate pH is -log[H+]

Hope it helps!
by Lorraine Jiang 2C
Sun Dec 06, 2020 2:24 am
Forum: Lewis Acids & Bases
Topic: Bronsted vs. Lewis bases
Replies: 11
Views: 70

Re: Bronsted vs. Lewis bases

Bronsted acids/bases and Lewis acids/bases are two sets of definitions of acids and bases. Bronsted focus on the transfer of protons and Lewis focus on the transfer of electron. For example, Bronsted acid is a proton donor, and lewis acid is an electron acceptor. However, there are cases of acids an...
by Lorraine Jiang 2C
Sun Dec 06, 2020 2:21 am
Forum: Naming
Topic: oxidation number on sapling question
Replies: 2
Views: 24

Re: oxidation number on sapling question

Hi! So from the question, we know that the total charge of the coordination compound is neutral, we know that the complex ion has a total charge of 1+ (since Cl is 1-). From that, we know that the ligand Cl has 1- charge, and there is one Cl ligand within the complex ion. Since the NH3 ligand is nat...
by Lorraine Jiang 2C
Sun Dec 06, 2020 2:17 am
Forum: Naming
Topic: Amphoteric Compund
Replies: 5
Views: 35

Re: Amphoteric Compund

Hi! Amphoteric compounds can act as either acids or bases. And there is a diagonal line of elements in the periodic table that forms amphoteric oxides, for example, BeO, Al2O3, Ga2O3... etc.) It is similar to the metalloid diagonal line but not exactly the same.

Hope it helps!
by Lorraine Jiang 2C
Sun Dec 06, 2020 2:14 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: ligands
Replies: 11
Views: 81

Re: ligands

NH3 is neutral because all of its atom's formal charges add up to 0.

Hope it helps!
by Lorraine Jiang 2C
Sun Dec 06, 2020 2:13 am
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Sapling Homework 9 Problem 2
Replies: 10
Views: 93

Re: Sapling Homework 9 Problem 2

Hi! So coordination number is basically the number of ligands bonded to the central transition metal in a complex ion.

Hope it helps!
by Lorraine Jiang 2C
Sat Nov 28, 2020 12:55 am
Forum: *Molecular Orbital Theory (Bond Order, Diamagnetism, Paramagnetism)
Topic: Sigma and Pi Bonds
Replies: 31
Views: 390

Re: Sigma and Pi Bonds

I think you just need to know that there is a sigma bond and two pi bonds in a triple bond, but I think it is most common to say sigma bond first before pi bonds.

Hope it helps!
by Lorraine Jiang 2C
Sat Nov 28, 2020 12:53 am
Forum: Hybridization
Topic: Sapling Week 7 & 8 HW Question 11
Replies: 14
Views: 107

Re: Sapling Week 7 & 8 HW Question 11

Hi! I think if you consider the region of electron density in this molecule it will be easier for you to determine the hybridization of the orbitals. For example, this molecule has 4 electron density regions so it will be sp^3 (1+3 = 4)

Hope it helps!
by Lorraine Jiang 2C
Sat Nov 28, 2020 12:50 am
Forum: Hybridization
Topic: Unhybridized p orbital energy
Replies: 4
Views: 77

Re: Unhybridized p orbital energy

Hi! I think you can think of hybridized orbitals a combination of s and p orbitals, and for 2sp^2 orbitals, it is closer towards the 2p orbital because it has slightly higher energy. And because of this, we will not have a paired electron spin at the 2sp^2 but a single electron at the 2p orbital bec...
by Lorraine Jiang 2C
Sat Nov 28, 2020 12:47 am
Forum: Hybridization
Topic: e density
Replies: 30
Views: 124

Re: e density

Yep! I think regions of electron density accounts for both bonded regions and lone pairs.

Hope it helps!
by Lorraine Jiang 2C
Sat Nov 28, 2020 12:45 am
Forum: Hybridization
Topic: Single Bonds and Sigma Bonds
Replies: 23
Views: 99

Re: Single Bonds and Sigma Bonds

Hi! I would remember it like this: Every single bond consists of a sigma bond, every double bond has a sigma bond and a pi bond, every triple bond has a sigma bond and two pi bonds...etc.

Hope it helps!
by Lorraine Jiang 2C
Wed Nov 18, 2020 11:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Molecular geometry vs. shape
Replies: 4
Views: 40

Re: Molecular geometry vs. shape

Hi! I think molecular geometry considers all-electron densities in a molecule, but a molecular shape only considers the bonded atoms. For example, if you have three atoms bonded to the central atom and you have a lone-pair, the molecular geometry is tetrahedral, but the molecular shape is Trigonal P...
by Lorraine Jiang 2C
Wed Nov 18, 2020 11:50 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bond angles
Replies: 16
Views: 246

Re: bond angles

I think we can predict the bond angles using the VSEPR theory, so for example how long-pairs repel each other more than lone-pairs repel a bonding pair. So if we have a lone-pair of electrons on the central atom we will know that the other atoms bonded to the central atom will be pushed down and the...
by Lorraine Jiang 2C
Wed Nov 18, 2020 11:48 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone Pair E-
Replies: 47
Views: 255

Re: Lone Pair E-

I think one lone pair of e- is counted as one electron density. So for example, like H2O, on the oxygen atom, there are two lone pairs of e- and we say there are four electron density clouds, 2 bonding and 2 lone-pairs.

Hope it helps!
by Lorraine Jiang 2C
Wed Nov 18, 2020 11:46 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Shape Names
Replies: 50
Views: 267

Re: Shape Names

Yes, the shape of H2O can either be bent or angular.
by Lorraine Jiang 2C
Wed Nov 18, 2020 11:44 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Electron density in VSEPR models
Replies: 4
Views: 31

Re: Electron density in VSEPR models

Hi! I think by "electron density" Dr. Lavelle is referring to different regions that have electrons. And he also mentioned that lone-pair vs lone-pair repulsion > long-pair vs. bonding pair repulsion > bonding pair vs. bonding pair repulsion. To answer your last question, the lone-pairs pu...
by Lorraine Jiang 2C
Thu Nov 12, 2020 10:16 am
Forum: Electronegativity
Topic: Confusion between electronegativity and electron affinity
Replies: 15
Views: 107

Re: Confusion between electronegativity and electron affinity

I think electronegativity and electron affinity are two different things. Electronegativity measures the tendency of an atom to attract a shared pair of electron. Electron affinity is the amount of energy released when an electron is added to an atom. The tendency to attract a pair of electron is di...
by Lorraine Jiang 2C
Thu Nov 12, 2020 10:11 am
Forum: Lewis Structures
Topic: Radicals
Replies: 12
Views: 38

Re: Radicals

Radicals have the key feature of having one unpaired electron next to it. It is usually represented like this: .CH3
Hope it helps!
by Lorraine Jiang 2C
Thu Nov 12, 2020 10:08 am
Forum: Dipole Moments
Topic: induced dipole vs dipole
Replies: 11
Views: 42

Re: induced dipole vs dipole

Only polar molecules can have dipole-dipole intermolecular force. A polar molecule means there is a difference between the electronegativity between the two bonded atoms so that one of them is delta positive and the other is delta negative. Induced dipole-induced-dipole occurs when two non-polar mol...
by Lorraine Jiang 2C
Thu Nov 12, 2020 10:05 am
Forum: Formal Charge and Oxidation Numbers
Topic: Calculating Formal Charge
Replies: 9
Views: 98

Re: Calculating Formal Charge

I think it is better to use the formal charge equation as well because it is the most straight forward way to solve the formal charge problems.
by Lorraine Jiang 2C
Thu Nov 12, 2020 10:03 am
Forum: Ionic & Covalent Bonds
Topic: Covalent vs Dipole Dipole
Replies: 4
Views: 25

Re: Covalent vs Dipole Dipole

Hi! So covalent bonds are known as intramolecular bonds, and dipole-dipole (and other examples professor Lavelle gave in the lecture e.g. hydrogen, dipole-induced dipole... etc.) are intermolecular bonds. The difference between intramolecular bonds and intermolecular bonds is that intramolecular mea...
by Lorraine Jiang 2C
Wed Nov 04, 2020 12:43 am
Forum: Trends in The Periodic Table
Topic: Effective nuclear charge
Replies: 4
Views: 21

Re: Effective nuclear charge

OH yes now I understand! Thank you so much Bella, Selena, and Will :))
by Lorraine Jiang 2C
Wed Nov 04, 2020 12:30 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: difference in p orbitals
Replies: 8
Views: 53

Re: difference in p orbitals

Hi! I think professor Lavelle mentioned that p orbitals have 3 parallel sub-orbitals: px, py, and pz, and each orbital can hold at most 2 electrons with opposite spins (ms). According to Hund's rule, we will fill one electron in all px, py, and pz sub-orbitals first before we started filling in the ...
by Lorraine Jiang 2C
Wed Nov 04, 2020 12:27 am
Forum: Trends in The Periodic Table
Topic: Effective nuclear charge
Replies: 4
Views: 21

Effective nuclear charge

Hi, can someone explain the concept of the effective nuclear charge? Is it the same as the shielding effect, so when electrons are further away from the nucleus they are more shielded by the inner electrons and they have a higher effective nuclear charge?

Thank you!
by Lorraine Jiang 2C
Wed Nov 04, 2020 12:25 am
Forum: Trends in The Periodic Table
Topic: Ionic Radius
Replies: 8
Views: 60

Re: Ionic Radius

If you are considering Na+ and F-, an easy way to think is to imagine that sodium has lost an outermost electron on its outermost shell, so it loses one shell (3s) and because of this, the electrostatic attraction is stronger and the nucleus will pull the other shells closer to it. so the radius dec...
by Lorraine Jiang 2C
Wed Nov 04, 2020 12:19 am
Forum: Trends in The Periodic Table
Topic: Inert-pair effect
Replies: 4
Views: 43

Re: Inert-pair effect

The inert-pair effect has to do with the tendency of the outermost two electrons in the s orbitals to remain unshared in post-transitional metals, and it explains why heavier atoms like Sb and Pb have a difference in the oxidation state of 2. But since professor Lavelle mentioned we only need to kno...
by Lorraine Jiang 2C
Wed Nov 04, 2020 12:13 am
Forum: Trends in The Periodic Table
Topic: Why is the ionization energy of O lower than N?
Replies: 13
Views: 90

Re: Why is the ionization energy of O lower than N?

I think oxygen has a lower ionization energy than Nitrogen is because an electron is added to an already half-filled p orbital. According to Hund's rule, half-filled orbitals are more stable, so it is fairly easy to remove the 'extra' electron in the p orbital in oxygen and that is why its first ion...
by Lorraine Jiang 2C
Thu Oct 29, 2020 9:35 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Orbital shapes
Replies: 3
Views: 38

Re: Orbital shapes

Hi! I think the nuclear charge doesn't really have much to do with the orbitals since they are just math functions that predict how the electrons will move. And I think you are right about electrons will get attracted to the nucleus (because of the nuclear charge) and that is the reason behind the s...
by Lorraine Jiang 2C
Thu Oct 29, 2020 9:31 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 4s and 3d
Replies: 14
Views: 102

Re: 4s and 3d

Hi! In general terms, the electrons have to fill up the 3d orbital first before they move on to the 4s orbital because it is at a lower energy state. But there are two exceptions, Potassium and Calcium, which fills the 4s orbital first.

Hope it helps!
by Lorraine Jiang 2C
Thu Oct 29, 2020 9:29 am
Forum: Quantum Numbers and The H-Atom
Topic: How many electrons in an atom could have these sets of quantum numbers?
Replies: 3
Views: 29

Re: How many electrons in an atom could have these sets of quantum numbers?

Hi! When ml is given we can basically just look at that and only 2 electrons can occupy an orbital so the answer will be 2. Hope it helps!
by Lorraine Jiang 2C
Thu Oct 29, 2020 9:25 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook question E31 and E33
Replies: 3
Views: 38

Re: Textbook question E31 and E33

Ok I got it! Thank you so much!
by Lorraine Jiang 2C
Thu Oct 29, 2020 9:24 am
Forum: Quantum Numbers and The H-Atom
Topic: Spin state
Replies: 25
Views: 170

Re: Spin state

Hi! The spin state (ms) is a fourth quantum number discovered after Schrodinger's wave function (which consists of 3 quantum numbers: n, l, ml). The spin state can either be (+1/2) or (-1/2). +1/2 means the electron is spinning upwards, and -1/2 means it is spinning downwards. And professor Lavelle ...
by Lorraine Jiang 2C
Thu Oct 22, 2020 5:58 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook question E31 and E33
Replies: 3
Views: 38

Textbook question E31 and E33

Hello! I know these two questions are not included in homework but I was doing them for extra practice and I couldn't get the correct answer.

For E31, I got the mass of water which is 1.6kg, but I couldn't find the cost of it.
If anyone can help with these two questions I would really appreciate it!
by Lorraine Jiang 2C
Wed Oct 21, 2020 1:09 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Textbook Problem 1B27
Replies: 6
Views: 49

Re: Textbook Problem 1B27

Hi! Whenever we are given "+ -" the delta x is always 2 times the number after "+-". I believe there is a mistake in the solution and here is the link to all the mistakes that professor Lavelle found. https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14A/Solution_Manu...
by Lorraine Jiang 2C
Wed Oct 21, 2020 1:02 am
Forum: DeBroglie Equation
Topic: Sapling Question 10
Replies: 5
Views: 87

Re: Sapling Question 10

Hi! I believe you will have to use the DeBroglie Equation for this question. To find the wavelength, take the Plank's constant and divide it by the momentum of the oxygen atom. Since the question gave us a hint about oxygen is a diatomic molecule, we need to use 16g/mol x 2 = 32g/mol, then convert i...
by Lorraine Jiang 2C
Wed Oct 21, 2020 12:56 am
Forum: DeBroglie Equation
Topic: Sapling Question 17
Replies: 2
Views: 22

Re: Sapling Question 17

Yep, I accidentally entered the wrong number in my calculator, and I got the same answer as you now! Thank you!
by Lorraine Jiang 2C
Wed Oct 21, 2020 12:55 am
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Electromagnetic radiation and associated energy levels
Replies: 4
Views: 44

Re: Electromagnetic radiation and associated energy levels

Hi! The infrared region is n=3 and it is called the Paschen series. I think in our tests we only need to perform calculations related to the Lyman series and the Balmer series.

Hope it helps!
by Lorraine Jiang 2C
Wed Oct 21, 2020 12:53 am
Forum: DeBroglie Equation
Topic: 1.B21
Replies: 3
Views: 35

Re: 1.B21

I think you should use DeBroglie's equation here. So first convert the 5.15 ounces to kg, then use Plank's constant divide the momentum of the baseball (mass times velocity) to get the wavelength. Hope it helps!
by Lorraine Jiang 2C
Wed Oct 21, 2020 12:42 am
Forum: DeBroglie Equation
Topic: Sapling Question 17
Replies: 2
Views: 22

Sapling Question 17

Hi, does anyone know how to do sapling question 17? I know I need to use the DeBroglie equation, but when I am converting mass, I used (35.45 x 2)/6.02 x 10^23 to find the mass of one chlorine atom. And then the question hints says that the mass needs to be in kg so I divided the number by 1000. May...
by Lorraine Jiang 2C
Fri Oct 16, 2020 3:13 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Homework Problem 1B.27
Replies: 2
Views: 23

Re: Homework Problem 1B.27

Hello! The answer should be 6.7 x 10^-37 m since there is a mistake in the textbook answer. Professor Lavelle has a list of mistakes in the textbook answers on his website and this is the link to the document: https://lavelle.chem.ucla.edu/wp-content/supporting-files/Chem14A/Solution_Manual_Errors_7...
by Lorraine Jiang 2C
Wed Oct 14, 2020 6:19 am
Forum: DeBroglie Equation
Topic: Question about post-module assessment
Replies: 5
Views: 94

Re: Question about post-module assessment

Nope, they will not. This is because their sizes are too big for them to have diffraction patterns. On the other hand, electrons, or photons, are small enough so that they will have diffraction patterns. I think professor Lavelle mentioned this before, that whether a diffraction pattern will occur i...
by Lorraine Jiang 2C
Wed Oct 14, 2020 6:14 am
Forum: Properties of Light
Topic: What exactly is Φ?
Replies: 16
Views: 153

Re: What exactly is Φ?

The work function, which is also called the threshold energy, is the minimum amount of energy required for the e- on an atom to be removed!

Hope it helps!
by Lorraine Jiang 2C
Wed Oct 14, 2020 6:10 am
Forum: Einstein Equation
Topic: Planck's Constant
Replies: 7
Views: 102

Re: Planck's Constant

Hi! I think professor Lavelle mentioned the Plank's constant was derived by plotting energy against frequency in a line graph. And the gradient of this graph will be Plank's constant. I think I have seen this in one of his modules, but I don't recall which one, I think it is not super important that...
by Lorraine Jiang 2C
Wed Oct 14, 2020 4:21 am
Forum: Properties of Light
Topic: Textbook Problem A.3
Replies: 2
Views: 24

Re: Textbook Problem A.3

Hi! I think the extent of the change in the electrical field at a given point means the amplitude of the wavelength on an electric field. Imagine if the frequency decreased, and we know that the wavelength would increase according to c = λ x ν, the waves will be longer and flatter (amplitude decreas...
by Lorraine Jiang 2C
Wed Oct 14, 2020 4:14 am
Forum: Properties of Light
Topic: Textbook Homework 1A.9
Replies: 4
Views: 33

Textbook Homework 1A.9

Hi everyone, I am working through the textbook questions and I got stuck by this question. 1A.9 A college student recently had a busy day. Each of the Student’s activities on that day (reading, getting a dental x-ray, making popcorn in a microwave oven, and acquiring a suntan) involved radiation fro...
by Lorraine Jiang 2C
Thu Oct 08, 2020 12:56 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook Homework E19
Replies: 2
Views: 26

Re: Textbook Homework E19

Oh Okay now I understand. Thank you Jenny!
by Lorraine Jiang 2C
Wed Oct 07, 2020 10:36 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Textbook Homework E19
Replies: 2
Views: 26

Textbook Homework E19

A report stated that the Sudbury Neutrino Observatory in Sudbury, Canada, uses 1.00 3 103 tonne (1 t 5 103 kg) of heavy water, D2O, in a spherical tank of diameter 12 m to detect neutri-43 reasoning. (The volume of a sphere of radius r is V 5 /3pr .) The density of normal water (H2O) at the temperat...
by Lorraine Jiang 2C
Wed Oct 07, 2020 2:10 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Chemical Formulas of Compounds
Replies: 9
Views: 114

Re: Chemical Formulas of Compounds

I think for the basic organic molecules like Methane, Butene, Methanol, Propanol, Butanoic acid...etc. We should know their chemical formulae. But for other more complex compounds like the one you mentioned, I think the question will provide us the IUPAC name, or the Lewis structure for us to figure...
by Lorraine Jiang 2C
Wed Oct 07, 2020 2:06 am
Forum: Balancing Chemical Reactions
Topic: Combustion
Replies: 14
Views: 189

Re: Combustion

I think Dr.Lavelle was giving us multiple examples of combustion. That includes the combustion of butane (which was the example), burning (of calories when we exercise), as well as oxidation. They all have similar reactions and they all release energy. For exmaple, combustion of butane requires oxyg...
by Lorraine Jiang 2C
Wed Oct 07, 2020 2:03 am
Forum: Balancing Chemical Reactions
Topic: Reaction Terminology "In excess"
Replies: 11
Views: 129

Re: Reaction Terminology "In excess"

I believe you are correct if the question says "in excess", then that means the molecule it is referring to is more than proportion than the other reactant molecule (which is the limiting reagent). Hope it helps!
by Lorraine Jiang 2C
Wed Oct 07, 2020 2:01 am
Forum: Balancing Chemical Reactions
Topic: Fractions
Replies: 34
Views: 566

Re: Fractions

I think in most cases we should always leave the Stoichiometric coefficients in integers, for example, in the butane combustion class example, professor Lavelle multiplied by all stoichiometric coefficients by 2 in order to have every coefficient as an integer. Unless the question specifically says ...
by Lorraine Jiang 2C
Wed Oct 07, 2020 1:58 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Avogadro's #
Replies: 31
Views: 361

Re: Avogadro's #

Avogadro's constant represents the relationship between the number of particles per mole. So we can use this relationship when the question is asking us to solve for example, how many particles are in x moles of y molecule. It is also an easy way for you to understand the concept of moles (mol) in c...
by Lorraine Jiang 2C
Mon Oct 05, 2020 2:13 am
Forum: Significant Figures
Topic: Significant Figures In A Given Weight
Replies: 11
Views: 186

Re: Significant Figures In A Given Weight

Hi! I think if the question states "7" then it has one significant figure only. Also, numbers like 70, 700, and 7,000 all have only one significant figure because I think there is a rule that states "the last zeros of an integer number do not count as significant numbers". Hope i...

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