CHEMISTRY COMMUNITY

Karina Koo 2H

9.47 Initially a sample of ideal gas at 323 K occupies 1.67 L at 4.95 atm. The gas is allowed to expand to 7.33 L by two pathways: (a) isothermal, reversible expansion; (b) isothermal, irreversible free expansion. Calculate Stot, S, and Ssurr for each pathway I dont understand how to solve part B. a...

Karina Koo 2H

Why does S total increase with irreversible but not reversible?

Karina Koo 2H

How do you calculate the standard entropy of vaporization of water at 85C, given that its standard entropy of vaporization at 100C is 109.0 J/K/mol and the molar heat capacities at constant pressure of liquid water and water vapor are 75.3 J/K/mol and 33.6 J/K/mol? For this problem, I used change in...

Karina Koo 2H

During the test of an internal combustion engine, 3.00L of nitrogen gas at 18.5 degrees C was compressed suddenly (and irreversibly) to .500L by driving in a piston. In the process the temperature of the gas increased to 28.1 degrees C. Assume ideal behavior and 1.00 mole of nitrogen gas. What is th...

Karina Koo 2H

A human body generates heat at the rate of about 100. W (1 W 1 J .s-'). (a)At what rate does your body heat generate entropy in your surroundings, taken to be at 20.0 C? (b)How much entropy do you generate each day? (c)Would the entropy generated be greater or less if you were in a room kept at 30° ...

Karina Koo 2H

which equation do u use for bomb calorimeters and which one do u use for normal calorimeters?

Karina Koo 2H

what are the units for PV=nRT?

Karina Koo 2H

is q always written as J and delta U and delta H always written as J/mol? (unless its specific aka over g)

Karina Koo 2H

the textbook states that reaction enthalpy is less negative than the reaction internal energy for reactions that generate gases. Why is this?

Karina Koo 2H

what is the conceptual difference of enthalpy and internal energy?

Karina Koo 2H

Can someone explain to me why the heat capacities for gas at a constant pressure are higher than that at constant volume? Thank you!

Karina Koo 2H

Can someone just conceptually explain what enthalpy is? I still dont quite get it because according to the textbook, enthalpy is a state function that keeps track of losses of energy as expansion work during heat transfer at constant pressure. So I would think enthalpy as something to do with work. ...

Karina Koo 2H

Do we need to know the equipartition theorem from the textbook in chapter 4B.3? if so, can someone explain this to me? I don't understand it. Thanks!

Karina Koo 2H

can someone explain to me why heat is not a state function? I read the textbook but i still dont get it. Thanks!

Karina Koo 2H

whats the difference between a bomb calorimeter and a normal one and how does this affect calculations?

Karina Koo 2H

whats the difference between the two?

Karina Koo 2H

A careless laboratory technician wants to prepare 200.0 mL of a 0.025 HCl (aq) solution but uses a volumetric flask of volume 250.0 mL by mistake. (a) what would the pH of the desired solution have been? (b) What will be the actual pH of the solution as prepared?

Karina Koo 2H

The photosynthesis reaction, 6 CO2(g) + 6 H2O(l) ⇌ C6H12O6(aq) + 6 O2(g), is endothermic. What effect will the following changes have on the equilibrium composition. a) Water is added. b) The partial pressure of CO2 is decreased. A. a) Decrease [C6H12O6] and [O2], b) Decrease [O2] B. a) Decrease [C6...

Karina Koo 2H

If we have a reaction that includes both gas and aqueous states, do we use partial pressure or concentration?

Karina Koo 2H

I'm still confused on why liquids are not included in calculating K while aqueous solutions are. Can someone explain this to me? Thanks!

Karina Koo 2H

Its because Cl is more electroneg than C and in CH4, everything is shared pretty evenly

Karina Koo 2H

In that case, I would think that whether the molecule is cis or trans will be given

Karina Koo 2H

a dipole moment happens when there are different charges between atoms. This can happen if one is more electronegative or maybe has a lone pair while the other doesn't. You can look at the shape of the molecule and how the atoms arrange themselves around the central atom to see if the molecule would...

Karina Koo 2H

van der waals happens everywhere, dipole dipole would happen if there are multiple polar molecules, and dipole induced dipole can occur with one polar and one nonpolar

Karina Koo 2H

it would be in between two polar molecules

Karina Koo 2H

Its probably possible on a different planet but since our atmosphere has a lot of CO2, probably not on earth.

Karina Koo 2H

@305127455 wait shouldnt pOH be 14-(-log[H+]) ?

Karina Koo 2H

What does the concentration constant symbolize?

Karina Koo 2H

identify the salt that is produced from a neutralization reaction between ammonia and phosphoric acid.
Can someone explain how to do this? Thanks!

Karina Koo 2H

Identify the salt that is produced from the acid base neutralization reaction between sodium hydroxide and propanoic acid CH3CH2COOH

Karina Koo 2H

is HN(CH2CH2NH2)2 polydentate and why? If so, what is the maximum amount of places this ligand can bind simultaneously to a metal ion?

Karina Koo 2H

which metal ions do we need to remember the special names of when naming coor. compounds? Thanks!

Karina Koo 2H

there might a difference but if there is, it's very slight. In Mr. Lavelle's lecture, he said both have the strength of about -2 KJ/mol

Karina Koo 2H

I think the words in bold from the textbook chapter might be good to know. Such as shielded, effective nuclear charge, penetrate, electron configuration, the pauli exclusion principle, paired, closed shell, core, valence electrons, parallel spins, the building-up principle, hund's rule, excited stat...

Karina Koo 2H

4p because it has more energy than 3d as seen by their n.

Karina Koo 2H

yup! I think youre on the right track that whatever has the lower n comes first, hence d usually ends up before s when its written out because of the fact that d is usually n-1 if the energy lv of s is n.

Karina Koo 2H

Give the notation for the valence-shell configuration (including the outermost d-electrons) of (a) the alkali metals; (b) Group 15 elements; (c) group 5 transition metals; (d) the "coinage" metals (Cu, Ag, Au).

Thanks!

Karina Koo 2H

I'm a bit confused on how to write the e- configuration of silver. I would think it's [Kr] 4d^9 5s^2 but according to the back of the 7th edition textbook, the answer is [Kr] 4d^10 5s^1. I'm noticing that this is kind of like the exceptions of copper and chromium mentioned in class, is this an excep...

Karina Koo 2H

Calculate the wavelength of a 275 kg single-seat electric car traveling at a speed of 125 km.hr-1. Do electric cars have wavelike properties?

Karina Koo 2H

If an electron (mass 9.11 x 10-31 kg) has an associated wavelength of 7.28 x 10-9 m, what is its speed? Is your answer reasonable, why?

Karina Koo 2H

yup. Each atom has it's own unique emission line spectrum and the equation was made specifically for hydrogen through finding the its line first and then coming up with an equation that made sense based on experimental data. Not to mention that multiple electrons complicates things a lot because ele...

Karina Koo 2H

It applies specifically to hydrogen atoms only and tells us how much energy is needed to bring an electron from the energy state n to the next lower energy state.

Karina Koo 2H

All that they are referring to is a series of wavelengths discovered that are able to be absorbed (and emitted) by a hydrogen atom. Lyman discovered a series of wavelengths that can be absorbed by a hydrogen atom in the UV light range, hence these series of wavelengths are called the Lyman series wh...

Karina Koo 2H

All that they are referring to is a series of wavelengths discovered that are able to be absorbed (and emitted) by a hydrogen atom. Lyman discovered a series of wavelengths that can be absorbed by a hydrogen atom in the UV light range, hence these series of wavelengths are called the Lyman series wh...

Karina Koo 2H

#41 states For the hydrogen atom which statement is true? A. The transition from n = 5 to n = 3 involves greater energy than one from n = 4 to n = 2. This is false because, as elections reach higher and higher energy states, the energy gap between each state gets smaller and smaller. Therefore, even...

Karina Koo 2H

The bohr frequency condition states that the energy of the photon must match the energy needed to bring an electron to a higher energy state exactly in order to be absorbed, so the wavelengths shown on the spectrums just show which ones fit this condition because certain wavelengths correspond to sp...

Karina Koo 2H

not sure if this is completely correct, but i think that this is because light being emitted and light being reflected are two different things. The light that is reflected is simply never absorbed and just bounces back because it doesn't match the energy required to bring the electron to a higher l...

Karina Koo 2H

Since the experiment is detecting absorbed light not emitted light, its just called absorption line spectrum. It shows what wavelengths are absorbed not which ones are emitted.

Karina Koo 2H

It's because the E in the Rydberg equation is measuring the amount of energy released when the electron jumps down to a lower energy level. The electron is losing energy, hence the negative value.

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