CHEMISTRY COMMUNITY

Ivy Kwok 2I

For this problem, the given ΔH° values are 1533 kJ, 3009 kJ, -348 kJ, and 445 kJ. With regards to sigfigs, why is the final answer is 3692 kJ, as opposed to 3690 kJ? Thank you!

Ivy Kwok 2I

The standard Gibbs free energy of activation is equal to ΔH°++ - TΔS°++. Because the standard Gibbs free energy of activation is always positive, ΔH°++ must be greater than ΔS°++, thus the standard enthalpy of is usually much larger than the standard entropy of activation. I'm not 100% sure if this ...

Ivy Kwok 2I

Ivy Kwok 2I

I believe that this concept has to do with the Arrhenius equation, which states that ln k = ln A - Ea / RT , or k = Ae^-^E^a^/^R^T . With this equation, increasing the temperature (T) will decrease the quantity Ea / RT , thus increasing the quantity Ae^-^E^a^/^R^T . Because e is an exponential funct...

Ivy Kwok 2I

You shouldn't drink water when studying because adding water to your system decreases concentration!

Ivy Kwok 2I

Ivy Kwok 2I

Yes, isothermal processes always constitute a constant temperature! It follows that ΔU = 0 because for ideal gases, the change in internal energy is dependent upon temperature; if T is not changing, neither will ΔU. And ultimately, q = -w.

Ivy Kwok 2I

It depends on the context of the system, from the perspective of the system! If it helps, you can think of internal energy change as ALWAYS being the ADDITION of q and w, but with varying signs (positive or negative). Positive denotes a gain and negative denotes a loss. In other words: - If the syst...

Ivy Kwok 2I

Yes! When the volume of the gas increases, the gas itself is the thing that is doing the work (for example, pushing up against a piston). If you think of the system from the perspective of the gas molecules, the gas is doing work, so it uses (and therefore loses) energy, as represented by the negati...

Ivy Kwok 2I

Ivy Kwok 2I

Before attempting the problem, it will be helpful to first convert all the given quantities into standard units! As such: • Diameter of pump (d) = 3 cm = 0.03 m. => Radius (r) = 0.015 m. • Distance compressed (x) = 20 cm = 0.2 m. • Pressure applied (P) = 2 atm = 2 x 1.0 x 10^5 Pa = 2.0 x 10^5 Pa. a)...

Ivy Kwok 2I

Q: Why does Nicki Minaj like NaOH?
A: It's a super base.

Ivy Kwok 2I

Thank you both!

Ivy Kwok 2I

Out of curiosity, why are strong acids considered strong acids if they lose hydrogen ions so easily?

Ivy Kwok 2I

Thank you to you both! (:

Ivy Kwok 2I

Will we have to consider sigfigs when performing calculations regarding equilibrium?

Ivy Kwok 2I

I believe that with regards to the ideal gas law, when the gas constant (R) is involved, we would use atmospheres, but in terms of other equations, we calculate using pascals.

Ivy Kwok 2I

Another approach would be to draw out the dipole moments (pointing toward the more electronegative atom in each case) and treat them like vectors. If all of the dipole moments have a corresponding equal and opposite one, then the molecule is nonpolar; if they do not, then the molecule is polar. It i...

Ivy Kwok 2I

HCl has more ionic bonds than H2S because there is a greater difference of electronegativity between the hydrogen and chlorine atoms than between the hydrogen and sulfur atoms. Additionally, because of this, the HCl molecule is also more polar than the H2S molecule.

Ivy Kwok 2I

Q: What's the significance of "NaCl/NaOH" in the context of video games?
A: Your base is under a salt (assault)!

Ivy Kwok 2I

Thank you so much!

Ivy Kwok 2I

May someone explain the second part of #2 on the Fall 2015 practice quiz? I balanced the equation, converted the given quantities of Al and HCl to moles, and did some dimensional analysis, but I can't seem to get the correct answer. Thank you! * Update: Aluminum and hydrogen chloride, HCl, react to ...

Ivy Kwok 2I

Diffraction patterns occur when a wave of light passes through multiple mediums / substances. Constructive interference occurs when the phase difference between two waves is a multiple of 2π (the peaks and troughs align), and destructive interference occurs when the phase difference between two wave...

Ivy Kwok 2I

My TA told me that we would be given just about all the necessary constants / formulas, and that we just need to make sure we know exactly when / how to use each one!

Ivy Kwok 2I

I believe we use grams when the problem involves chemistry concepts (e.g. converting substances to moles) for the majority and kilograms when the problem involves physics concepts (e.g. kinetic energy in the photoelectric effect) for the majority.

CHEMISTRY COMMUNITY

Search found 25 matches

Winter 2014 Final Exam #1

Re: Question 4.37

Re: Post All Chemistry Jokes Here

Re: Effects of Temperature on Rate Constant

Re: Post All Chemistry Jokes Here

Re: Post All Chemistry Jokes Here

Re: isothermal

Re: How to Calculate the Change in Internal Energy

Re: Work Equation [ENDORSED]

Re: Post All Chemistry Jokes Here

Re: Chapter 8 #3

Re: Post All Chemistry Jokes Here

Re: Strong Acids

Strong Acids

Re: Significant Figures [ENDORSED]

Significant Figures [ENDORSED]

Re: PV=nRT

Re: Polar vs Nonpolar

Re: H2S and HCl

Re: Post All Chemistry Jokes Here

Re: Fall 2015 Quiz #2 [ENDORSED]

Fall 2015 Quiz #2 [ENDORSED]

Re: Diffraction Patterns and Interacting Waves

Re: Formulas need to know? [ENDORSED]

Re: When do we know whether to use gram vs. kilogram, etc.? [ENDORSED]