Search found 66 matches

by Salena Chowdri 1I
Sun Mar 17, 2019 1:58 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Effects of Compression
Replies: 5
Views: 211

Re: Effects of Compression

Yes compression would effect the position of a reaction, taking it away from equilibrium. When the volume reduces, the side that has less gas molecules is favored. The compression increases pressure because of the gaseous state.
by Salena Chowdri 1I
Sun Mar 17, 2019 1:56 am
Forum: Applying Le Chatelier's Principle to Changes in Chemical & Physical Conditions
Topic: Le Chatelier's Principle
Replies: 2
Views: 173

Re: Le Chatelier's Principle

When the concentration of reactants increases, forward reaction is favored (vice versa)
When the temperature increases for an endothermic reaction, forward reaction is favored (vice versa)
When gas is compressed, the side that has less gas molecules will be favored
by Salena Chowdri 1I
Sun Mar 17, 2019 1:55 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: When is delta U = 0?
Replies: 4
Views: 219

Re: When is delta U = 0?

For an isothermal system delta U = 0
by Salena Chowdri 1I
Sun Mar 17, 2019 1:53 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011787

Re: Post All Chemistry Jokes Here

If the Silver Surfer and Iron Man team up, they’d be alloys.
by Salena Chowdri 1I
Sun Mar 17, 2019 1:52 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011787

Re: Post All Chemistry Jokes Here

Q: What is the chemical formula for "coffee"?
A: CoFe2
by Salena Chowdri 1I
Sun Mar 17, 2019 1:52 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011787

Re: Post All Chemistry Jokes Here

Why do chemists like nitrates so much?
They're cheaper than day rates.
by Salena Chowdri 1I
Sun Mar 17, 2019 1:52 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011787

Re: Post All Chemistry Jokes Here

Did you know that you can cool yourself to -273.15˚C and still be 0K?

yikes that wasn't such hot joke.
by Salena Chowdri 1I
Sun Mar 17, 2019 1:51 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011787

Re: Post All Chemistry Jokes Here

Why can't you trust atoms?

They make up everything haha
by Salena Chowdri 1I
Sun Mar 17, 2019 1:49 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Largest E Cell
Replies: 2
Views: 171

Re: Largest E Cell

You would subtract the most positive reduction potential from the most negative reduction potential.
by Salena Chowdri 1I
Sun Mar 17, 2019 1:48 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: What is pKa and Ka exactly?
Replies: 11
Views: 1015

Re: What is pKa and Ka exactly?

Ka is acid dissociation constant and represents the strength of the acid. pKa is the -log of Ka, having a smaller comparable values for analysis. They have an inverse relationship. Larger the Ka, smaller the pKa and stronger the acid.
by Salena Chowdri 1I
Sun Mar 17, 2019 1:41 am
Forum: Non-Equilibrium Conditions & The Reaction Quotient
Topic: Increasing volume
Replies: 3
Views: 181

Re: Increasing volume

Yes if the volume increases K will indicate movement to whichever side has less gas molecules, this is because an increase in volume (expansion) is indicative of a decrease in pressure.
by Salena Chowdri 1I
Sun Mar 17, 2019 1:40 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Pt
Replies: 2
Views: 170

Re: Pt

Platinum is an inert element the is used as an electrode for whichever side lacks a solid
by Salena Chowdri 1I
Sun Mar 17, 2019 1:34 am
Forum: Reaction Mechanisms, Reaction Profiles
Topic: Pre-equilibrium Approach
Replies: 2
Views: 216

Re: Pre-equilibrium Approach

For K, we only consider the aqueous and gaseous states, and ignore the liquids and solids
by Salena Chowdri 1I
Sun Mar 17, 2019 1:33 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: Cell Diagram
Replies: 2
Views: 158

Cell Diagram

If H+(aq) is added in the half equation, how do you know where to put it for the cell diagram?
by Salena Chowdri 1I
Sun Mar 17, 2019 1:28 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: Exothermic vs. Endothermic
Replies: 5
Views: 237

Re: Exothermic vs. Endothermic

Both endothermic and exothermic reactions have Ea, however endothermic reactions will have a larger energy barrier to go over.
by Salena Chowdri 1I
Sun Mar 17, 2019 1:26 am
Forum: General Rate Laws
Topic: Rate constant units
Replies: 3
Views: 181

Re: Rate constant units

The units for rate are mol.L-1.s-1, change of concentration over change in time. The rate constant units depend on the order of the reaction. To put it simply, a 0th order k: mol.L-1.s-1, 1st order k: s-1, 2nd order k: mol-1.L.s-1
by Salena Chowdri 1I
Sun Mar 17, 2019 1:24 am
Forum: Arrhenius Equation, Activation Energies, Catalysts
Topic: catalyst vs intermediate
Replies: 3
Views: 198

Re: catalyst vs intermediate

Catalysts are there from the beginning, but are never consumed. However, intermediates are formed and consumed within the reaction.
by Salena Chowdri 1I
Sun Mar 17, 2019 1:23 am
Forum: Ideal Gases
Topic: ICE table
Replies: 3
Views: 213

Re: ICE table

Ka is [A-][H+]/[HA], so if you have the initial concentration of HA you'll be able to calculate the concentration of hydrogen ions.
by Salena Chowdri 1I
Sun Mar 17, 2019 1:20 am
Forum: Balancing Redox Reactions
Topic: Balanced Half Reactions
Replies: 5
Views: 199

Re: Balanced Half Reactions

you will need to balance the number of ions and electrons for each half reaction and then to combine them and get an overall reaction you will need to balance both half equations to have the same number of electrons.
by Salena Chowdri 1I
Sun Mar 17, 2019 1:13 am
Forum: Second Order Reactions
Topic: 6th edition 15.39
Replies: 2
Views: 207

Re: 6th edition 15.39

the rate law isn't directly related to the coefficients of the reactants
by Salena Chowdri 1I
Sun Mar 17, 2019 1:03 am
Forum: Thermodynamic Systems (Open, Closed, Isolated)
Topic: Adiabatic and isothermal
Replies: 6
Views: 407

Re: Adiabatic and isothermal

An adiabatic process occurs without transfer of heat or mass of substances between a thermodynamic system and its surroundings. In an adiabatic process, energy is transferred to the surroundings only as work. An isothermal process is a change of a system, in which the temperature remains constant: Δ...
by Salena Chowdri 1I
Sun Mar 17, 2019 1:01 am
Forum: Appications of the Nernst Equation (e.g., Concentration Cells, Non-Standard Cell Potentials, Calculating Equilibrium Constants and pH)
Topic: Nernst Equation Confusion
Replies: 4
Views: 223

Re: Nernst Equation Confusion

They are the same, however the second equation is commonly used in questions that ask for pH to be found from the [H+]
by Salena Chowdri 1I
Sun Mar 17, 2019 1:00 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: pseudo rate law
Replies: 7
Views: 238

Re: pseudo rate law

So the pseudo rate law just allows easier analysis of the effect of one reactant. In this case, the other reactant(s) are in high concentration that they can be considered constant, and so k[high conc. reactant] is k'
by Salena Chowdri 1I
Sun Mar 17, 2019 12:58 am
Forum: *Enzyme Kinetics
Topic: Adsorption
Replies: 11
Views: 476

Re: Adsorption

Adsorption occurs with a heterogeneous catalyst, it provides a solid surface area for compounds to react.
by Salena Chowdri 1I
Sun Mar 17, 2019 12:57 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Units of k
Replies: 5
Views: 212

Re: Units of k

we know that the units for rate are mol.L-1.s-1 Zero order: rate =k[A]^0 so units of k have to be the same as the units for the rate First order: rate =k[A] the multiplication of the units of k and units of concentration of A (i.e mol.L-1) should result in the units for the rate; thus, units of k is...
by Salena Chowdri 1I
Sun Mar 17, 2019 12:54 am
Forum: Galvanic/Voltaic Cells, Calculating Standard Cell Potentials, Cell Diagrams
Topic: cell concentration
Replies: 1
Views: 160

Re: cell concentration

Did you mean to upload a picture for this question?
by Salena Chowdri 1I
Sun Mar 17, 2019 12:49 am
Forum: Calculating Standard Reaction Entropies (e.g. , Using Standard Molar Entropies)
Topic: molar mass
Replies: 2
Views: 338

Re: molar mass

It would depend on what formula and variables you have to calculate the entropy.
by Salena Chowdri 1I
Sun Mar 17, 2019 12:35 am
Forum: Concepts & Calculations Using First Law of Thermodynamics
Topic: first law
Replies: 2
Views: 172

Re: first law

The first law states that in an isolated system, there is no change in internal energy. So w=-q.
by Salena Chowdri 1I
Sun Mar 17, 2019 12:34 am
Forum: Balancing Redox Reactions
Topic: balaning redox reactions
Replies: 3
Views: 223

Re: balaning redox reactions

In the example of 2Fe^2+, a reduction reaction would look like:

2Fe^2+ + 4e- ---> 2Fe

I hope this answered your question!
by Salena Chowdri 1I
Sun Mar 17, 2019 12:32 am
Forum: Method of Initial Rates (To Determine n and k)
Topic: Units k
Replies: 1
Views: 179

Re: Units k

This would depend on the order of the reaction! It's easiest to write out the units for each individual element of the rate law and cancel out units from there. Here's a short cut though: first order: s^-1, second: mol^-1.L.s^-1, third: mol^-2.l^2.s^-1
by Salena Chowdri 1I
Mon Jun 11, 2018 2:11 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011787

Re: Post All Chemistry Jokes Here

Q: Did you hear oxygen went on a date with potassium?
A: It went OK
by Salena Chowdri 1I
Mon Jun 11, 2018 2:11 am
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011787

Re: Post All Chemistry Jokes Here

Why do chemists like nitrates so much?
They're cheaper than day rates.
by Salena Chowdri 1I
Sat Jun 09, 2018 4:36 pm
Forum: Bronsted Acids & Bases
Topic: J.5
Replies: 2
Views: 192

Re: J.5

^^ you'd have to know that non-metals create acids, most metals form bases and i think you'll have to remember the middle section of amphoteric elements.
by Salena Chowdri 1I
Sat Jun 09, 2018 4:34 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical to molecular
Replies: 3
Views: 364

Re: Empirical to molecular

calculate what the molar mass of the empirical formula is, let's call this 'x'. The question, more often than not, will provide you with the actual molar mass of the compound ('y'). Divide 'y' by 'x', this will give you the ratio of empirical formula to molecular. Using the whole number obtained, mu...
by Salena Chowdri 1I
Sat Jun 09, 2018 4:28 pm
Forum: Dipole Moments
Topic: Are London dispersion forces present in every molecule?
Replies: 2
Views: 150

Re: Are London dispersion forces present in every molecule?

London dispersion forces are present between any 2 molecules that are close together
by Salena Chowdri 1I
Sat Jun 09, 2018 4:26 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Oxidation Number
Replies: 5
Views: 311

Re: Oxidation Number

The oxidation number of a free element is always 0. The oxidation number of a monatomic ion equals the charge of the ion.
by Salena Chowdri 1I
Wed Jun 06, 2018 9:16 pm
Forum: Conjugate Acids & Bases
Topic: pKa [ENDORSED]
Replies: 3
Views: 249

Re: pKa [ENDORSED]

You will need to find the concentration of products (ions) and the initial acid through experimentation (when mixed with water). In this case, pH is often equal to pKa. The general equation would be: [+ion][-ion]/[acid]
by Salena Chowdri 1I
Wed Jun 06, 2018 9:10 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011787

Re: Post All Chemistry Jokes Here

What do dipoles say in passing?

Have you got a moment?
by Salena Chowdri 1I
Wed Jun 06, 2018 9:06 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011787

Re: Post All Chemistry Jokes Here

You'd think that atoms bonding with other atoms would mean they're being friendly, but really they steal each other's electrons.

How ionic.
by Salena Chowdri 1I
Wed Jun 06, 2018 9:03 pm
Forum: Hybridization
Topic: Pi bonds in triple bond
Replies: 17
Views: 434

Re: Pi bonds in triple bond

There are 2 pi bonds in a triple bond and 1 pi bond in a double bond.
by Salena Chowdri 1I
Wed Jun 06, 2018 3:54 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar VS Nonpolar shapes
Replies: 4
Views: 162

Re: Polar VS Nonpolar shapes

The dipole moments have to be equal in strength, so 2 of the same bonds can cancel each other out. "Cancel" here means opposing vectors. However, when you're considering whether a compound is polar or nonpolar always think of the structure in 3D.
by Salena Chowdri 1I
Wed Jun 06, 2018 3:38 pm
Forum: Electronegativity
Topic: HW question 3.77
Replies: 3
Views: 243

Re: HW question 3.77

The electronegativity difference between C and H is less than the difference between C and F. C and H have almost the same electronegativity.
by Salena Chowdri 1I
Sat Jun 02, 2018 2:01 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011787

Re: Post All Chemistry Jokes Here

Initially I decided to write jokes about the Periodic Table, but never really felt I was in my element.
by Salena Chowdri 1I
Wed May 30, 2018 5:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: lone pairs
Replies: 5
Views: 182

Re: lone pairs

Commonly, a linear compound consists of 3 atoms that lie at 180 degrees. The compound takes a bent structure when there is a lone pair found on the central atom (usually on top). This creates a repelling force that pushes both the present bonds downwards into a 120 degree angle.
by Salena Chowdri 1I
Wed May 30, 2018 4:16 pm
Forum: Ionic & Covalent Bonds
Topic: Double/Triple Bonds
Replies: 8
Views: 299

Re: Double/Triple Bonds

most atoms are capable of having double or triple bonds. It's just a matter of oxidation states and formal charges in order to create the most stable structure of the compound. They are usually added to complete the octet of atoms.
by Salena Chowdri 1I
Wed May 30, 2018 4:02 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond angles and lone pairs
Replies: 4
Views: 192

Re: Bond angles and lone pairs

if you are given just the bond angle and number of atoms involved, you'll know a lone pair is involved when the bond angle is smaller than usual. this is because lone pairs repel the bonded pairs, causing the angle to be smaller.
by Salena Chowdri 1I
Wed May 30, 2018 3:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR confusion
Replies: 8
Views: 315

Re: VSEPR confusion

^^ Valence shell electron pair repulsion (VSEPR) theory is a model used in chemistry to predict the geometry of individual molecules from the number of electron pairs surrounding their central atoms. The VSEPR formula is just the structure.
by Salena Chowdri 1I
Wed May 30, 2018 3:33 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 7569
Views: 1011787

Re: Post All Chemistry Jokes Here

Q: How often does this group tell chemistry jokes?
A: Periodically!
by Salena Chowdri 1I
Wed May 30, 2018 3:29 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Cancelling out dipole moments
Replies: 3
Views: 178

Re: Cancelling out dipole moments

Once you draw out the compound, the biggest thing that will help you are the dipole arrows in relation to the elements involved. If you have an asymmetrical structure that's one sign but when deciding if something is polar or nonpolar check if the arrows of 2 identical bonds cancel out (are exactly ...
by Salena Chowdri 1I
Mon May 14, 2018 6:57 pm
Forum: Significant Figures
Topic: what part of the probem to apply sig fig rules
Replies: 2
Views: 174

Re: what part of the probem to apply sig fig rules

It's best not to round off any values used in the calculation. Only apply the sig fig rule to your final answer. This will give you the most accurate value!
by Salena Chowdri 1I
Sun May 13, 2018 5:22 pm
Forum: Properties of Light
Topic: Test 2 Question 4
Replies: 8
Views: 281

Re: Test 2 Question 4

Most students attempted to solve this problem using Rydberg's, however that is not necessary. The question already mentions that energy is released in the form of light at 400nm. The energy produced by this wavelength is the "energy difference". So all we need is to plug in the wave length...
by Salena Chowdri 1I
Sun May 13, 2018 5:18 pm
Forum: Lewis Structures
Topic: Expanded Octet
Replies: 2
Views: 102

Re: Expanded Octet

These elements are capable of forming expanded octets (some more often than others), but you will not always find the elements in that state. For instance, compare Sulfur oxide (SO2) to sulfur hexafluoride (SF6).
by Salena Chowdri 1I
Sun May 13, 2018 5:15 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Calculating formal charges
Replies: 5
Views: 194

Re: Calculating formal charges

To calculate the formal charge, subtract the sum of the total number of lone electrons and total number of bonds (0.5 x total number of bonded electrons) from the number of valence electrons of that specific atom. All the atoms FC should add up to the compounds overall charge. It is preferred to hav...
by Salena Chowdri 1I
Sun May 13, 2018 5:10 pm
Forum: Lewis Structures
Topic: BrO- Lewis Structure
Replies: 2
Views: 287

Re: BrO- Lewis Structure

Hypobromite ion would have one covalent bond between the Br and O atoms. Both atoms would have complete octets but the oxygen atom would have a -1 charge due to an extra electron.
by Salena Chowdri 1I
Sat May 12, 2018 5:52 pm
Forum: Ionic & Covalent Bonds
Topic: HW problem 3.21
Replies: 4
Views: 188

Re: HW problem 3.21

The answer key is right; the ground state electron configuration for Ag+ is [kr] 4d^10 and has no unpaired electrons. The ground state electron configuration for just Ag is [kr] 4d^10 5s^1. Since Ag+ has a charge of +1, that means it is losing an electron to become more positive. Since 5s has a high...
by Salena Chowdri 1I
Sat May 12, 2018 5:43 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal charges and full valence shells
Replies: 3
Views: 173

Re: Formal charges and full valence shells

There's no direct relationship between formal charges and full valence shells. Full valence shells do no always result in a formal charge of zero, they can result in formal charges of -1,+1 and others. The formal charge is calculated by subtracting the sum of the number of lone pair electrons and th...
by Salena Chowdri 1I
Sat May 12, 2018 5:36 pm
Forum: Ionic & Covalent Bonds
Topic: Why can't hydrogen be a central atom? [ENDORSED]
Replies: 6
Views: 393

Re: Why can't hydrogen be a central atom? [ENDORSED]

Hydrogen can't be the central atom because it can only form one bond, so it must generally be in the outer layer of atoms. When drawing a lewis structure, it's recommended for hydrogen atoms to be added in last.
by Salena Chowdri 1I
Sat May 12, 2018 5:31 pm
Forum: Ionic & Covalent Bonds
Topic: Nonpolar covalent bonds
Replies: 2
Views: 113

Re: Nonpolar covalent bonds

A covalent bond is a chemical bond that involves the sharing of electron pairs between atoms. Lewis structures are often used to depict the sharing of electrons between atoms in a covalently bonded compound.
by Salena Chowdri 1I
Wed Apr 18, 2018 9:08 pm
Forum: Empirical & Molecular Formulas
Topic: empirical vs molecular
Replies: 5
Views: 282

Re: empirical vs molecular

The empirical formula is the most simplified version of the formula, with the smallest ratio of whole numbers. So if glucose C6H1206 was divided by 3, we would get CH2O which is that most simplified formula. The molecular accounts for the actual state of the compound and its atomic binding.
by Salena Chowdri 1I
Wed Apr 18, 2018 9:06 pm
Forum: Limiting Reactant Calculations
Topic: Limiting Reactants
Replies: 5
Views: 245

Re: Limiting Reactants

If you want to find the limiting reactant of this question, you would first need to calculate the number of moles present of each reactant (by using the molar mass and given mass). Then use the ratio of 1 mole of CaC2: 2 moles of H2O to deduce which of the reactants is actually present in excess.
by Salena Chowdri 1I
Wed Apr 18, 2018 9:03 pm
Forum: Significant Figures
Topic: Rounding: when and where?
Replies: 10
Views: 470

Re: Rounding: when and where?

As mentioned above, don't round off until the final answer. Your answer would not be marked as wrong but maybe to be safe in parenthesis mention that number of sig figs you've rounded to. However, the general rule is round off to the lowest number of sig figs given in the question asked.
by Salena Chowdri 1I
Wed Apr 18, 2018 8:59 pm
Forum: DeBroglie Equation
Topic: 10^-18
Replies: 3
Views: 116

Re: 10^-18

As Jack said, the EMS has currently identified wavelengths between the range of 10^(-18) to approximately 100 km. Since the smallest identifiable wavelength is to the 10^-18 (gamma waves), anything smaller than that is undetectable. The car mentioned in class would be considered a classical particle...
by Salena Chowdri 1I
Wed Apr 18, 2018 8:55 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Frequency if energy goes from n=2 to n=4
Replies: 6
Views: 215

Re: Frequency if energy goes from n=2 to n=4

When you go from a lower energy level to a higher level, energy is require. The electron absorbs this energy, over releasing a photon. So as mentioned, photons will not have a negative value of energy. However, the change in energy of the electron will be positive going up energy levels and negative...
by Salena Chowdri 1I
Wed Apr 18, 2018 8:49 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: The Negative Sign in En = -hR/n^2
Replies: 5
Views: 158

Re: The Negative Sign in En = -hR/n^2

That is correct. The energized electron falls from a higher energy level to a lower energy level (releasing photons). The release of energy causes the change in energy (Delta E) to be a negative value.

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