Search found 17 matches

by Rebecca Sine 1K
Wed Mar 09, 2016 4:51 pm
Forum: Polyprotic Acids & Bases
Topic: PUBLIC SERVICE ANNOUNCEMENT
Replies: 1
Views: 443

Re: PUBLIC SERVICE ANNOUNCEMENT

Chemistry joke somewhat related to day-light savings:

Question: Why do chemists like nitrates so much?
Answer: They're cheaper than day rates.
by Rebecca Sine 1K
Mon Feb 22, 2016 3:39 pm
Forum: Student Social/Study Group
Topic: Post All Chemistry Jokes Here
Replies: 8017
Views: 1402220

Re: Chemistry Jokes

354nh2.jpg
by Rebecca Sine 1K
Sun Feb 14, 2016 11:06 am
Forum: General Rate Laws
Topic: 15.17
Replies: 1
Views: 264

Re: 15.17

When you want to figure out the reaction order of one reactant (let's say A for example), choose an experiment in which the initial concentrations of the other reactants (B and C) stay the same. For the two experiments that you choose to compare, only the initial concentrations of A should be differ...
by Rebecca Sine 1K
Mon Feb 01, 2016 1:33 pm
Forum: Balancing Redox Reactions
Topic: A Little Helpful Tip
Replies: 1
Views: 340

A Little Helpful Tip

In the course reader, the acronym "LEO" is used as a way to remember that "Losing Electrons is Oxidation". Another great way to remember this by using the acronym "OIL RIG" (a device used to extract natural gas), which stands for "Oxidation Is Loss" and "...
by Rebecca Sine 1K
Tue Jan 12, 2016 4:15 pm
Forum: Phase Changes & Related Calculations
Topic: negative and positive work
Replies: 1
Views: 213

Re: negative and positive work

I think when we use this version of the work equation (W = F x D), we can do work on an object in any state of matter as long as we apply a force (F) and manage to move the object over a certain distance (D). However, I think the modified version of the equation (W = P x deltaV), can only be used on...
by Rebecca Sine 1K
Sun Jan 10, 2016 3:46 pm
Forum: Reaction Enthalpies (e.g., Using Hess’s Law, Bond Enthalpies, Standard Enthalpies of Formation)
Topic: Delta H of Formation of Diatomic Molecules
Replies: 2
Views: 509

Re: Delta H of Formation of Diatomic Molecules

I think that the formation of gaseous Br2 would have a delta-H value that is something other than zero; it's likely that you'll only ever find the delta-H of Br2 to be zero when in it's in its natural liquid state.
by Rebecca Sine 1K
Sun Nov 29, 2015 9:50 pm
Forum: Bronsted Acids & Bases
Topic: Bronsted Acid and Base
Replies: 1
Views: 366

Re: Bronsted Acid and Base

Common compounds that can act as both an acid and base are buffers - they can either provide or accept protons in order keep a solution at a certain pH. Although buffers can act in either capacity, a buffer will often be classified as a weak acid or weak base. So although the chemical makeup of a bu...
by Rebecca Sine 1K
Sun Nov 22, 2015 8:24 pm
Forum: Polyprotic Acids & Bases
Topic: Ka for Polyproptic Acids
Replies: 2
Views: 510

Re: Ka for Polyproptic Acids

After each reaction that occurs as a polyprotic acid dissociates, the Ka gets smaller and smaller. This is because it is harder for the acid to lose protons as it acquires a negative charge.
by Rebecca Sine 1K
Sun Nov 15, 2015 12:23 pm
Forum: Biological Examples
Topic: Summary of Biological Importance
Replies: 2
Views: 485

Re: Summary of Biological Importance

Coordination compounds involving chromium helps control blood sugar by helping insulin function. Coordination compounds involving iron form myoglobin and hemoglobin complexes that transport oxygen through the bloodstream. Coordination complexes involving cobalt are involved in the role of B-vitamins.
by Rebecca Sine 1K
Sat Nov 07, 2015 4:59 pm
Forum: Equilibrium Constants & Calculating Concentrations
Topic: Approximations
Replies: 1
Views: 230

Re: Approximations

The reason why equilibrium expressions are only considered approximations may be because we only include gaseous and aqueous compounds in the expressions. Solids and liquids are excluded because they undergo extremely insignificant changes in concentration. However, those changes are still changes a...
by Rebecca Sine 1K
Sat Oct 24, 2015 3:58 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: helpful VSEPR chart
Replies: 1
Views: 268

Re: helpful VSEPR chart

Thank you!
by Rebecca Sine 1K
Sat Oct 24, 2015 3:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining bond angles
Replies: 3
Views: 442

Re: Determining bond angles

Oops, in the first example I meant C2H4, not C2H2.
by Rebecca Sine 1K
Sat Oct 24, 2015 2:50 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Determining bond angles
Replies: 3
Views: 442

Re: Determining bond angles

Looking at C2H2 as a simple example, we know that each carbon has a trigonal planar VSEPR shape. Therefore the bond angle of every atom surrounding each of the two carbons will be 120 degrees. Keep in mind that three atoms are required to form an angle, like three points in geometry. For more comple...
by Rebecca Sine 1K
Thu Oct 15, 2015 4:51 pm
Forum: Empirical & Molecular Formulas
Topic: Empirical Formula
Replies: 1
Views: 356

Re: Empirical Formula

Let’s imagine that we determined that 100 grams of a certain compound had 40.9 grams of carbon, 4.58 grams of hydrogen, and 54.5 grams of oxygen. Finding the empirical formula of this compound means finding the basic ratio of each of the elements. To do this, we need to know how many moles of each e...
by Rebecca Sine 1K
Thu Oct 08, 2015 11:08 pm
Forum: Properties of Electrons
Topic: Homework Problems 1.33 and 1.37
Replies: 1
Views: 418

Re: Homework Problems 1.33 and 1.37

For #1.33, we need to use the "de Broglie" equation, which is "lamda=h/(m*v)". Lambda is wavelength, "h" is Planck's Constant (6.626*10^-34 J*s), "m" is the mass of an electron (9.10939*10^-31 kg), and v is the velocity of the electron. (a) We are given the ve...
by Rebecca Sine 1K
Fri Oct 02, 2015 12:37 am
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Deriving ΔV from the Uncertainty Equation
Replies: 1
Views: 321

Deriving ΔV from the Uncertainty Equation

Knowing that Δp*Δx = h bar/2, may I please know how one can manipulate this equation to find the equation for ΔV (in detail)? Measured in meters per second, why is ΔV used to denote uncertainty in position in the answer and not ΔX? These questions arise from the context of problem number 43 of chapt...

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