## Search found 61 matches

Mon Jan 18, 2021 1:46 am
Forum: Ideal Gases
Topic: Units for Pressure
Replies: 41
Views: 807

### Re: Units for Pressure

I think from examples in lecture atm tends to be used more often
Mon Jan 18, 2021 1:44 am
Forum: Ideal Gases
Topic: Inverse Kc
Replies: 24
Views: 55

### Re: Inverse Kc

The inverse K provided the K value of the reverse reaction, but can also be helpful when solving a question that requires combining or manipulating several reactions.
Mon Jan 18, 2021 1:42 am
Forum: Ideal Gases
Topic: PV=nRT
Replies: 72
Views: 438

### Re: PV=nRT

P = Pressure, typically in atm or bars
V = Volume, Liters
n = # of moles
R = gas constant (which I believe is provided on the equations sheet)
T = temperature, Kelvin
Mon Jan 18, 2021 1:40 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: ICE table values
Replies: 18
Views: 51

### Re: ICE table values

I believe that keeping your units in Mol/L is helpful to preventing calculation errors, so it is recommended.
Mon Jan 18, 2021 1:39 am
Forum: Ideal Gases
Topic: R Value
Replies: 16
Views: 33

### Re: R Value

Hi! I believe the value will be provided for us on the equations and formulas sheet we’re allowed to use.
Sun Jan 10, 2021 11:51 pm
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Using Kc Vs Kp
Replies: 22
Views: 245

### Re: Using Kc Vs Kp

We use Kc if the problem uses concentrations, but we use Kp if the problem provides partial pressures.
Sun Jan 10, 2021 11:49 pm
Forum: Ideal Gases
Topic: Inert Gases
Replies: 11
Views: 36

### Re: Inert Gases

Changing the pressure will not change the concentrations because we calculate K through quantity per volume, and an inert gas does not affect the equilibrium reaction.
Sun Jan 10, 2021 11:45 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Rice method correlation [ENDORSED]
Replies: 4
Views: 26

### Re: Rice method correlation[ENDORSED]

The RICE method is basically the same as the ICE table we can use.
Sun Jan 10, 2021 11:43 pm
Forum: Ideal Gases
Topic: Gas constant R
Replies: 26
Views: 93

### Re: Gas constant R

The gas constant R is universal and is provided to us on the equations sheet.
Sun Jan 10, 2021 10:33 pm
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Kelvin or Celsius?
Replies: 57
Views: 1300

### Re: Kelvin or Celsius?

Use Kelvin because it will cancel with the units for R.
Thu Dec 17, 2020 2:12 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Bent vs Angular
Replies: 20
Views: 97

### Re: Bent vs Angular

I believe bent and angular are synonymous, although for this class we tend to use the term bent more often.
Thu Dec 17, 2020 2:11 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Tetrahedral molecular shape
Replies: 10
Views: 69

### Re: Tetrahedral molecular shape

The tetrahedral has 4 bond angles of about 109.5* rather than 90* because, with three-dimensional space, we are not limited to a single plane. Since we are trying to give the atoms the highest amount of distance between one another, we would utilize the three-dimensional space so that their placemen...
Thu Dec 17, 2020 2:07 am
Forum: Determining Molecular Shape (VSEPR)
Topic: What are the bond angles for T shaped?
Replies: 17
Views: 116

### Re: What are the bond angles for T shaped?

The bond angles should be a bit less than 90* due to the lone pairs.
Thu Dec 17, 2020 2:05 am
Forum: Determining Molecular Shape (VSEPR)
Topic: wedge and dash
Replies: 14
Views: 96

### Re: wedge and dash

Hi! The wedge indicates the bond coming towards you while the dashed line represents the bond extending further away from your perspective. They’re both supposed to help us visualize the orientation of the bonds in three dimensional space
Thu Dec 17, 2020 2:04 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Seesaw vs. trigonal pyramidal
Replies: 22
Views: 132

### Re: Seesaw vs. trigonal pyramidal

Hi! They aren’t the same shape; seesaw has 5 regions of electron density, one of which is a lone pair (AX4E), whole trigonal pyramidal has 4 regions of electron density, one of which is a lone pair (AX3E).
Sun Dec 06, 2020 11:14 pm
Forum: Dipole Moments
Topic: Dipole canceling
Replies: 13
Views: 78

### Re: Dipole canceling

Yes! Even when a molecule has polar bonds within it, those individual interactions do not determine the overall polarity of the molecule on their own. It depends on whether the dipoles within the molecule have something to cancel them out, which results in a nonpolar molecule.
Sun Dec 06, 2020 11:11 pm
Forum: Bond Lengths & Energies
Topic: Higher Melting Point
Replies: 27
Views: 214

### Re: Higher Melting Point

CHI3 has the higher melting point because Iodine is a larger atom than Fluorine, which has the smaller atomic radius. Since it is larger, Iodine has higher LDFs and polarizability, and since more energy to break interactions means a higher temperature, CHI3 will have the higher melting point.
Sun Dec 06, 2020 11:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: polar v nonpolar molecules
Replies: 30
Views: 144

### Re: polar v nonpolar molecules

Polar molecules are when the bonded atoms have an electro negativity difference and asymmetry is observed where dipole forces are not canceled out. On the other hand nonpolar molecules are when electrons are shared equally among the atoms of the molecule or when the dipole forces cancel one another ...
Sun Dec 06, 2020 11:02 pm
Forum: Determining Molecular Shape (VSEPR)
Replies: 5
Views: 39

Yes, both are considered angular or bent. The general shapes of the structure are described, but the angles depend on what atoms are involved and if lone pairs are present. Because lone pairs are present in this case, the bond angles between the other regions will be a bit less because the lone pair...
Sun Dec 06, 2020 10:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angle
Replies: 4
Views: 43

### Re: Bond angle

The shape is bent because in addition to the two atoms that the central atom is bound to, there are also two lone pairs which will had a repelling effect and contribute to the total of four electron density regions. With four regions trying to have the greatest amount of distance between them, the b...
Mon Nov 30, 2020 12:03 am
Forum: Lewis Structures
Topic: Tips on drawing Lewis structures
Replies: 20
Views: 139

### Re: Tips on drawing Lewis structures

Hi! I sometimes have difficulty drawing Lewis Structures too, but what I do to prevent errors is that I always check I have the correct number of electrons that includes the valence electrons of the atoms as well as the charge if applicable. Another thing that helps is noticing how the formula is wr...
Mon Nov 30, 2020 12:01 am
Forum: Dipole Moments
Topic: Dipole arrows
Replies: 8
Views: 46

### Re: Dipole arrows

Dipole arrows will point towards the end which has higher electronegativity. For that question we had to consider how the different dipole forces would create a net dipole force, and in which direction.
Sun Nov 29, 2020 11:57 pm
Forum: Sigma & Pi Bonds
Topic: Strength of bonds
Replies: 5
Views: 56

### Re: Strength of bonds

Pi bonds are probably stronger because they are found in double and triple bonds while sigma bonds are found in any covalent bond.
Sun Nov 29, 2020 11:55 pm
Forum: Ionic & Covalent Bonds
Topic: Polar and Nonpolar
Replies: 28
Views: 174

### Re: Polar and Nonpolar

It helps to take into account the 3D shape of the molecule rather than just the Lewis structure, as the Lewis structure may lead us to believe it is nonpolar when it is actually polar, and vice versa. Sometimes I will look at the symmetry of the forces acting on the molecule, because if it is symmet...
Sun Nov 29, 2020 11:51 pm
Forum: Lewis Acids & Bases
Topic: angle size
Replies: 11
Views: 75

### Re: angle size

I agree with previous replies that having a chart for reference is very helpful. I've found that with time and having completed more exercises, it has become easier to recall what types of shape and angle sizes would be associated with the molecule. Drawing out the molecule can also help.
Tue Nov 24, 2020 12:37 am
Forum: Dipole Moments
Topic: Polarity
Replies: 30
Views: 152

### Re: Polarity

I think one method of figuring out if a molecule is polar or not, even when it has dipole forces, is to look at the molecule's structure and determine whether it has symmetry or not. If it has symmetry, in most cases it will not be polar, even when it has dipole forces, because they will cancel out.
Tue Nov 24, 2020 12:28 am
Forum: Bond Lengths & Energies
Topic: Covalent Bond Length
Replies: 13
Views: 127

### Re: Covalent Bond Length

Electronegativity, Atomic radius, Bond type (Triple, Double, or Single), among other factors will affect bond length and in turn, bond strength. Shorter bonds tend to be stronger than longer bonds, and molecules with stronger bonds typically have a higher boiling point as a result.
Tue Nov 24, 2020 12:21 am
Forum: Electronegativity
Topic: determining electronegativity
Replies: 31
Views: 253

### Re: determining electronegativity

The general periodic trend for electronegativity is that it increases from left to right for periods and down to up for groups.
Tue Nov 24, 2020 12:17 am
Forum: Lewis Structures
Topic: Dot stucture
Replies: 11
Views: 66

### Re: Dot stucture

You typically start by counting the number of valence electrons each atom would normally have, and distributing them accordingly. The central atom tends to be the one with the lowest ionization energy, which is often a Carbon atom. Once you have finished drawing out your bonds and filling out the oc...
Tue Nov 24, 2020 12:08 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Example of s-orbital wave function equation
Replies: 2
Views: 45

### Re: Example of s-orbital wave function equation

Sun Nov 15, 2020 11:53 pm
Forum: Ionic & Covalent Bonds
Topic: bond lengths
Replies: 9
Views: 55

### Re: bond lengths

I believe double bonds are stronger than single bonds because the shorter distance between the atoms makes the double bond stronger than the single bond. This might be due to the idea that the pull of the nucleus is stronger the closer the object is to the nucleus.
Sun Nov 15, 2020 11:47 pm
Forum: Coordinate Covalent Bonds
Topic: Hydrogen bonding
Replies: 15
Views: 112

### Re: Hydrogen bonding

Hydrogen bonding is a type of intermolecular force and dipole-dipole interaction, but is not a coordinate covalent bond.
Sun Nov 15, 2020 11:43 pm
Forum: Trends in The Periodic Table
Topic: Electron affinity and Ionization energy
Replies: 7
Views: 60

### Re: Electron affinity and Ionization energy

Hello! Ionization energy is the energy needed to remove an electron from an atom (gas phase). The further the electron is from the nucleus, the easier it is to remove. The trend for ionization energy increases as you move right across a period and up a group. On the other hand, Electron affinity is ...
Sun Nov 15, 2020 11:38 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Textbook problem 1D.1
Replies: 3
Views: 36

### Re: Textbook problem 1D.1

I believe it is a conceptual principle that was mentioned in the Quantum Numbers and Atomic Orbitals Lecture, in which it was stated that the Principle Quantum Number (n) determines energy and size
Sun Nov 15, 2020 11:35 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Structure plausibility
Replies: 5
Views: 34

### Re: Structure plausibility

I had difficulty determining the plausibility of the structure as well, but I mainly looked at how the charges were dispersed throughout the structure (evenly or not), and if an electronegative atom was holding the charge (I believe my TA mentioned that the more electronegative the atom, the better ...
Mon Nov 09, 2020 12:01 am
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Parallel electrons
Replies: 7
Views: 56

### Re: Parallel electrons

Hund's Rule states that due to electron repulsion electrons in the same subshell, l, will occupy different orbitals with parallel spins and are unpaired. Paired electrons have opposite spins and are in the same orbital.
Sun Nov 08, 2020 11:58 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: What are orbitals?
Replies: 10
Views: 112

### Re: What are orbitals?

It was mentioned in lecture that an orbital is a math function with three quantum numbers (n, l, m. I think orbitals are 3D representations of the space where an electron can be found rather than indicators of an electron's specific position, especially considering the movement of electrons.
Sun Nov 08, 2020 11:50 pm
Forum: Einstein Equation
Topic: E=pc vs E=hv
Replies: 15
Views: 144

### Re: E=pc vs E=hv

E = hv is only used for finding the energy of photons/light, while E = pc can be used for particles with mass.
Sun Nov 08, 2020 11:27 pm
Forum: Properties of Light
Topic: Amplitude and Intensity Relationship
Replies: 4
Views: 29

### Re: Amplitude and Intensity Relationship

Intensity is proportional to amplitude so that when one increases, so will the other.
Sun Nov 08, 2020 11:23 pm
Forum: Properties of Electrons
Topic: Elements with similar number of electrons
Replies: 9
Views: 54

### Re: Elements with similar number of electrons

Hello! I think that, due to the periodic table being arranged in part by the number of protons the element has, similar characteristics can be noted within a certain grouping of elements. This further plays out in the trends that can be seen in the periodic table, such as the trend of electronegativ...
Mon Nov 02, 2020 12:07 am
Forum: Lewis Acids & Bases
Topic: Water
Replies: 62
Views: 487

### Re: Water

Pure water is neutral and is neither acidic or basic. However, depending on the question and context provided, water can act as an acid or base.
Mon Nov 02, 2020 12:04 am
Forum: Empirical & Molecular Formulas
Topic: Empirical formula question
Replies: 7
Views: 46

### Re: Empirical formula question

There can only be whole numbers in an empirical formula, as it is the simplest positive integer ratio of atoms in a compound.
Mon Nov 02, 2020 12:00 am
Forum: Balancing Chemical Reactions
Topic: Balancing Equations Coefficient Question
Replies: 15
Views: 108

### Re: Balancing Equations Coefficient Question

Yes, you would want to multiply your coefficients by the same number in order to get whole ratios. As long as you preserve the ratio, multiplying the coefficients is fine.
Sun Nov 01, 2020 11:57 pm
Forum: *Liquid Structure (Viscosity, Surface Tension, Liquid Crystals, Ionic Liquids)
Topic: determining viscosity
Replies: 11
Views: 98

### Re: determining viscosity

There are multiple methods to measuring a liquid's viscosity, such as measuring the rate at which it flows through a narrow tube. The more viscous the liquid the slower it will flow.
Sun Nov 01, 2020 11:38 pm
Forum: Significant Figures
Topic: Sig Figs and Scientific Notation
Replies: 10
Views: 97

### Re: Sig Figs and Scientific Notation

The 10x portion does not count as part of your sig figs, as your sig figs should be focused on nonzero values or zeros that are considered significant due to their placement.
Sun Oct 25, 2020 7:48 pm
Forum: Properties of Light
Topic: Light spectrum
Replies: 8
Views: 59

### Re: Light spectrum

I think we should try to memorize the order and wavelengths of electromagnetic radiation. One of the TAs covered a question in which we had to know the wavelength, as it wasn't provided
Sun Oct 25, 2020 7:02 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: for test 1
Replies: 14
Views: 223

### Re: for test 1

I think it would definitely be helpful to understand these concepts, as we will probably have to identify their meanings and different applications in future chem classes. Furthermore, these terms are often used in lab settings, so it would be better to understand what it means when your data is acc...
Sun Oct 25, 2020 6:57 pm
Forum: SI Units, Unit Conversions
Topic: Can someone explain Avogrado's #?
Replies: 8
Views: 91

### Re: Can someone explain Avogrado's #?

Avogadro's number is the number of objects in one mole of a substance. You can use it to describe the number of atoms, molecules, etc there are in a mole of whatever substance because it is just a number.
Sun Oct 25, 2020 6:50 pm
Topic: What is Black Body?
Replies: 35
Views: 563

### Re: What is Black Body?

Black Body refers to a material that could, in theory, absorb all wavelengths of light, which renders it invisible due to no light reflecting off of its surface, which is required for us to see an object.
Sun Oct 25, 2020 6:39 pm
Forum: Balancing Chemical Reactions
Topic: Naming compounds
Replies: 21
Views: 192

### Re: Naming compounds

Hi! As previous replies have states, we don't need to memorize a bunch of compounds for now. However, if you want to start practicing how to name compounds, I think there is a section of the textbook fundamentals that covered the topic. I believe it was 1D, but I'm not entirely certain.
Sun Oct 18, 2020 10:54 pm
Forum: SI Units, Unit Conversions
Topic: Metric Conversions
Replies: 9
Views: 117

### Re: Metric Conversions

For the acronym mentioned a couple comments above, the Great Master Knight Did Commit Murder Under No Pretenses, it goes G - giga 10^9 M - mega 10^6 K - kilo 10^3 D - deci 10^-1 C - centi 10^-2 M - milli 10^-3 u - micro 10^-6 n - nano 10^-9 p -pico 10^-12 In this acronym Giga is the prefix with the ...
Sun Oct 18, 2020 7:36 pm
Forum: Photoelectric Effect
Topic: Light Intensity
Replies: 23
Views: 109

### Re: Light Intensity

You're correct, the brighter light was caused by an increase in photons. For the experiment they realized that increasing the intensity of the light did not change the energy of the photons, because it is a change in wavelength/frequency that causes that change.
Sun Oct 18, 2020 7:27 pm
Forum: Properties of Electrons
Topic: protons and electrons
Replies: 33
Views: 191

### Re: protons and electrons

Protons and neutrons have a similar mass, which is about 1 amu, while electrons have what is considered negligible mass.
Sun Oct 18, 2020 7:24 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactants (Practice Problem)
Replies: 5
Views: 52

### Re: Limiting Reactants (Practice Problem)

The reactant which will run out of moles first in relation to the molar ratios expressed in the chemical equation will be the limiting reactant. For example, if you have 5 moles of Oxygen and 20 moles of Hydrogen, but the molar ratio given by the balanced chemical reaction states that the ratio betw...
Sun Oct 18, 2020 7:16 pm
Forum: Empirical & Molecular Formulas
Topic: F3 Part A (Textbook)
Replies: 6
Views: 47

### Re: F3 Part A (Textbook)

In order to determine the formula for nitric acid you can refer to what was suggested in the textbook, -ate ions go with -ic acids, while -ite ions go with -ous acids". We know that in most cases acids typically begin with H, and that because its nitric acid, the hydrogen is paired with nitrate...
Sun Oct 18, 2020 7:11 pm
Forum: SI Units, Unit Conversions
Topic: (M1)(V1)=(M2)(V2) with L vs mL
Replies: 5
Views: 39

### Re: (M1)(V1)=(M2)(V2) with L vs mL

I would recommend maintaining the same units throughout your calculations so that it is less likely that your conversions are off. Before starting to solve the problem, converting the units into Liters would probably be better.
Sun Oct 11, 2020 6:03 pm
Forum: Significant Figures
Topic: Sapling #4
Replies: 10
Views: 70

### Re: Sapling #4

Non-zero digits are always significant. On the other hand, zeros are only significant if they are between two non-zero digits (Ex: 3004 has four sig figs) or if they are trailing a digit with a decimal (Ex:30.00 has four sig figs). I believe there is a module reviewing sig figs on the chemistry webs...
Sun Oct 11, 2020 5:57 pm
Forum: Ionic & Covalent Bonds
Topic: Determining Empirical Formula (HW Question)
Replies: 6
Views: 143

### Re: Determining Empirical Formula (HW Question)

This question also confused me initially, but I decided to first convert the grams of CO2 and grams of H2O into moles because I knew that is usually one of the steps in solving for the empirical formula. After doing so I realized that it was critical to the problem that we know what mass of oxygen w...
Sun Oct 11, 2020 5:42 pm
Forum: Limiting Reactant Calculations
Topic: Sapling Homework Week 1 Q10
Replies: 6
Views: 132

### Re: Sapling Homework Week 1 Q10

I also assumed a 1:1 ratio for the 2-butanone: 3-methyl 3-hexanol. The value provided in my version of the question was 0.30 mL of 2-butanone, which I then converted to grams and then moles. I calculated 0.0034 moles of 2-butanone, so therefore there was 0.0034 moles of 3-methyl 3-hexanol. Next I co...
Sun Oct 11, 2020 5:36 pm
Forum: Balancing Chemical Reactions
Topic: Order of Balancing Rxns
Replies: 23
Views: 115

### Re: Order of Balancing Rxns

I think a part of balancing equations is intuition and trial and error, but in my own experience I tend to first look at all of the elements involved and then see which one is the most limited in the sense that it appears in the equation a lesser amount of instances than the other elements. I then w...
Sun Oct 11, 2020 5:32 pm
Forum: Empirical & Molecular Formulas
Topic: Sapling Homework 1 Q#9
Replies: 21
Views: 248

### Re: Sapling Homework 1 Q#9

This question also confused me initially, but I decided to first convert the grams of CO2 and grams of H2O into moles because I knew that is usually one of the steps in solving for the empirical formula. After doing so I realized that it was critical to the problem that we know what mass of oxygen w...