CHEMISTRY COMMUNITY

Jessica Dharmawan 1G

Are there any specific biological examples that we need to know for the final? In terms of structure, function, etc.

Jessica Dharmawan 1G

I feel like there might be a practice final because Lyndon, who did the Garlic Bread midterm questions last time, has a session on Friday. He might tell us in class during one of the lectures this week. Also, I assume that the TAs and UAs will also go over practice final questions during their own s...

Jessica Dharmawan 1G

What are the electronegativity cut offs that can be used to determine if a bond is ionic/covalent?

Jessica Dharmawan 1G

When doing calculations, should we use 2.99792 × 10⁸ m.s^-1 or 3.00 × 10⁸ m.s^-1 for the speed of light?
I used the 3.00 × 10⁸ m.s^-1 on the midterm and got an answer that was two hundredths off and got it marked wrong, so what should be the accurate number to use?

Jessica Dharmawan 1G

What is the easiest/quickest way to determine what the limiting reagent in a chemical reaction is?

Jessica Dharmawan 1G

What's the easiest way to determine hybridization schemes for certain molecules?

Jessica Dharmawan 1G

What's the significance of sigma and pi bonds? How are they useful to know when looking at molecular interactions?

Jessica Dharmawan 1G

What is hybridization in general, in terms of its definition as well as how it is used in the context of this lesson?

Jessica Dharmawan 1G

The shortcut is basically to first count how many electrons are surrounding a single atom. For example, when looking at the formal charge for Cl in PCl 5 , you would count that there are 6 lone electrons and then one electron right next to the Cl that is being shared with the P (in other words, only...

Jessica Dharmawan 1G

Is there a way to determine bond length of a Lewis structure with single/double/triple bonds? Or does that information have to be given to us in the problem?

Jessica Dharmawan 1G

When do we multiply the uncertainty in p or x or v by 2? I'm getting confused when doing calculations.

Jessica Dharmawan 1G

The radius of the atom represents 1/2 of the uncertainty of the position of the electron, the diameter equaling the entire uncertainty. the size of the atom represents the uncertainty in position. You can use this uncertainty, as well as the mass of an electron and the constant h/4pi to calculate d...

Jessica Dharmawan 1G

The question states: The hydrogen atom has a radius of approximately 0.05 nm. Assume that we know the position of an electron to an accuracy of 1 % of the hydrogen radius, calculate the uncertainty in the speed of the electron using the Heisenberg uncertainty principle. Comment on your value obtaine...

Jessica Dharmawan 1G

The question states: Calculate the uncertainty (indeterminacy) in position of an electron if its uncertainty in speed is one hundredth the speed of light.

Does this mean the uncertainty is 3x10^6? if so, does delta v = 2(3x10^6)?

Jessica Dharmawan 1G

The question asks: An excited hydrogen atom emits light with a frequency of 1.14 x 10^14 Hz to reach the energy level n = 4. In what principle quantum level did the electron begin?

What is the easiest way to solve this?

Jessica Dharmawan 1G

In the photoelectric effect, do we look at the light as waves or photons? I keep getting confused with questions asking for example: if long wavelength light is not ejecting e- from a surface, will increasing intensity of light result in e- being ejected?? I think increasing the intensity of light w...

Jessica Dharmawan 1G

When there's a problem asking for the change in energy from n=3 to n=1 of a hydrogen atom, how many sig figs should our answer have, since there's only one sig fig from the given data?

Jessica Dharmawan 1G

Roman numerals are used to name the different ions of the transition metals. An example would be: Cu3+ named as Cu(III).

Jessica Dharmawan 1G

I know that ionization energy is the energy needed to remove an electron from an atom. The further away the electron is from the nucleus, the easier it is to remove the electron. Ionization energies decrease down a group and increase across a period.

Jessica Dharmawan 1G

What is the easiest way to find the number of elements that have given quantum numbers?
Example: given n = 5 and l = 1, how many elements can have these quantum numbers?

Jessica Dharmawan 1G

As the light source is increased in intensity, then the number of electrons ejected increases. Light intensity is proportional to the number of electrons ejected.

Jessica Dharmawan 1G

It is better to round off at the end of the problem, instead of in the middle of a calculation, to ensure accuracy. Use as many digits as possible in the middle of a calculation and just carry those numbers over until you're at the end of the problem.

Jessica Dharmawan 1G

Should we also know conversions like M (mega)? It was on the homework so I'm just wondering

Jessica Dharmawan 1G

It's good to know them for context and conceptual understanding, but we don't have to know how to draw them.

Jessica Dharmawan 1G

What are the equations we should memorize for Test 2?

Jessica Dharmawan 1G

Do we have to memorize these for the test this week?

Jessica Dharmawan 1G

I looked at formula units as the number of atoms/molecules, depending on what is given. I used Avogadro's number to find the formula units asked for in the problem.

Jessica Dharmawan 1G

The test was fairly straightforward, and most of the problems were similar to the homework problems. It was also pretty short, and most of us finished early, giving us time to even check back on all of the problems again.

Jessica Dharmawan 1G

I'm having trouble finding easy ways to determine the limiting reactant. Any advice??? There is also a problem in one of the post-assessment modules that asks questions about the chemical equation 2A + 1B --> 3C, such as what reactant is in excess and what is the maximum amount of product that can b...

Jessica Dharmawan 1G

I believe you do multiply by 2 when using H2. Because there are two atoms of hydrogen, you would multiply the molar mass of 1 H atom by 2 to get the total molar mass of H2.

Jessica Dharmawan 1G

On question #17, it asks us to balance the equation $CH_{}4 + O_{}2 \rightarrow CO_{2} + H_{2}O$ .
I believe the correct answer is C) $2CH_{}4 + 4O_{}2 \rightarrow 2CO_{2} + 4H_{2}O$ , but the survey says it is wrong, maybe it's a typo?

Jessica Dharmawan 1G

I believe Dr. Lavelle said we should include the state of matter when balancing an equation. We will probably be able to recognize the states of matter as we go along and do problems, so I think we will pick it up eventually. If not, then the state of matter will be stated in the question. To balanc...

CHEMISTRY COMMUNITY

Search found 32 matches

What should we know for the final?

Re: Final [ENDORSED]

Ionic/Covalent bond cut offs

Speed of light

Finding limiting reagent

Hybridization scheme

Significance of sigma and pi bonds

General definition/context

Re: Shortcut

Determine bond length

When to multiply by 2

Re: Post-Module Q#18

Post-Module Q#18

Post-Module Q#17

Post-Module Q#42

Photoelectric Effect - waves vs. photons

Sig figs???

Re: Roman numerals next to element

Re: Periodic table

Finding number of elements that have given quantum numbers

Re: Photoelectric Effect

Re: Sig Figs in the Middle of a Problem

Re: SI Units

Re: Test Question

Test 2 Equations

Re: Lyman, Balmer, Pascal

Re: formula units [ENDORSED]

Re: Test 1

How to find the limiting reactant easily and quickly

Re: When to use H vs H2

Post-Module Assessment typo?? - Balancing Chemical Reactions

Re: How To....