CHEMISTRY COMMUNITY

Daniel Zhang 1E

Yes! Since it is required to boil it is just the amount of heat needed to get to boiling point. Vaporization would occur at anything above 100 degrees celsius the difference comes from the wording, if it had said vaporize we would use the enthalpy of vaporization but since it says to boil we can om...

Daniel Zhang 1E

In Q1A of the 2011 Final, it asks for us to calculate the amount of methane needed to combust to generate enough heat to boil 50.0mL of water. However, in the solutions it does not consider the amount of energy required to vaporize the water - it only considers the energy to raise the temperature to...

Daniel Zhang 1E

Keep in mind that triple bonds have priority for lowest numbering in alkynes

Daniel Zhang 1E

Double and triple bonds have priority over substituents and should always be given the lowest possible number. For substituents, you give priority to them based on alphabetical order. Alphabetical order does not include any of the prefixes (di, tri, etc.) and it does not include the common prefixes...

Daniel Zhang 1E

How do we know when to use each classification? When do we know whether or not we should classify according to cis and trans or z and e?

Daniel Zhang 1E

How come for 4-ethyl-2,2-dimethyl-hexane dimethyl is prioritized for lower numbering? Shouldn't ethyl be prioritized so that it would be 3-ethyl-5,5-dimethyl-hexane because ethyl is listed first in the name?

Daniel Zhang 1E

How do we know which of these two methods to use? Are there specific conditions we should look for or will the question tell us which of the two to use?

Daniel Zhang 1E

But the units don't cancel out? It's $\frac{2x}{x^{2}}$

Daniel Zhang 1E

Are we supposed to include spectator ions when we draw the cell diagrams in line notation? Online sources say that you shouldn't but the solution for 14.15 says that you should.

Daniel Zhang 1E

For question 4 on the 2011 practice midterm, the answer was given in bar even though there was no indication of it being used in the constants provided. How do we know to use bar rather than kPa or atm?

Daniel Zhang 1E

An isolated system is similar to a calorimeter with a lid. None of the matter inside will come out, and the calorimeter will contain any transfer of energy between the system and its surroundings. An closed system is like a lightbulb. It is sealed so that none of the components can come out but can ...

Daniel Zhang 1E

Which work equation should we use for problems with isothermal, reversible reactions at constant pressure? The course reader says to use $w = -P\Delta V$ for reversible expansions with constant pressure and $w = -nRTln(V_{2}/V_{1})$ for isothermal, reversible expansions with variable pressure.

Daniel Zhang 1E

So would we assume that the pressure has decreased after the ammonia has become a gas?

Daniel Zhang 1E

Diatomic molecules will tend to have higher entropy due to this equation: S = k_{b}lnW The number of microstates (W) is given by the equation: W = m^{n} m is the number of states while n is the total number of particles. A diatomic molecule would have a greater number of microstates and, therefore, ...

Daniel Zhang 1E

Why is it that ammonia can remain in a gaseous state while below the temperature of vaporization? For question 9.20, we are supposed to calculate the standard entropy of vaporization of ammonia @210K. The temperature of vaporization of ammonia is 329.4K. To do the problem, we have to assume the liqu...

Daniel Zhang 1E

How do we know when or what gas constants to use when calculating for the change in internal energy of a gas with constant pressure? For example, 8.9 from the textbook uses 8.314 and 0.08206, but how did they know to use these constants?

Daniel Zhang 1E

Here's my video on how to find the empirical formula of a compound. Contributors include: Anthony Giron, Carrie Huang, and Daniel Zhang.

Daniel Zhang 1E

Does the formal charge or the octet rule create a more stable Lewis structure for elements who can have expanded octets? For example, sulfur in SO _{2} can form a double bond with both oxygens to have a low formal charge. However, sulfur would have an expanded octet. If sulfur formed a double bond w...

Daniel Zhang 1E

Why is the electron configuration for tungsten $4f^{14}5d^{4}6s^{2}$ instead of $4f^{14}5d^{5}6s^{1}$ ? Shouldn't the 6s orbital lend an electron to the 5d orbital for a more stable half-orbital?
This is based on the answer for 2.43 from the textbook, part e).

Daniel Zhang 1E

You can use both equations. If using the Rydberg you can use the frequency value to find E with $E = \textit{h}\nu$

You can plug this into the Rydberg formula to figure out the principle quantum level the electron started from.

CHEMISTRY COMMUNITY

Search found 20 matches

Re: Why is heat of vaporization not considered in this probl

Why is heat of vaporization not considered in this problem?

Re: Naming

Re: Numbering Carbons

Cis and trans vs Z and E

Prioritizing in naming

Pre-equilibrium vs steady-state

Re: How to know what units for pressure to use?

Cell diagrams and spectator ions

How to know what units for pressure to use?

Re: How to identify systems

Isothermal, reversible expansion at constant pressure

Re: Standard entropy of vaporization of ammonia

Re: Diatomic vs Monotomic Gases Clarification

Standard entropy of vaporization of ammonia

Using ideal gas constants

Video: Empirical Formulas

Formal charge vs octet rule

Electron Configuration for Tungsten (W)

Re: Rydberg vs. Bohr equation for hydrogen atom