CHEMISTRY COMMUNITY

Abby Ellstrom 1I

In this class it is only possible to have single slow step mechanisms.

Abby Ellstrom 1I

You use a pseudo first order reaction when there is more than one reactant by making one of the reactant's concentrations very large so you can test the rate while manipulating the other reactant.

Abby Ellstrom 1I

A unique rate is the same for all of the materials in the reaction (products and reactants) because it multiplies the change in substance by one over its coefficient.

Abby Ellstrom 1I

'n' half lives refer to how many times the concentration has been halved at that point.

Abby Ellstrom 1I

The differential rate law is the rate as a function of the concentration and the integrated rate law is the rate as a function of time.

Abby Ellstrom 1I

In acidic conditions the Hydrogen is balanced by H+ and H20 molecules and in basic conditions the Hydrogen is balanced by H20 and OH- molecules.

Abby Ellstrom 1I

These equations are essentially the same so you can use them interchangeably depending on which information you have.

Abby Ellstrom 1I

The oxidation half reaction includes the electrons on the right side of the arrow.

Abby Ellstrom 1I

You swipe the sign on the anode by using the equation E_cell=E_cathode-E_anode

Abby Ellstrom 1I

You put solids on the outside and aqueous solutions on the inside.

Abby Ellstrom 1I

Yes since G is a state property it is additive.

Abby Ellstrom 1I

1. Identify which species is being oxidized and which is being reduced. 2. Separate into half reactions. 3. For each one, balance the oxygen by adding H2O to the other side for each O you need. 4. Then balance the hydrogen by adding H+ to the side that needs it. 5. Make sure the reduction and oxidat...

Abby Ellstrom 1I

Work does affect pressure. W=-PdV

Abby Ellstrom 1I

Cv is when the volume is constant and Cp is when the pressure is constant.

Abby Ellstrom 1I

Reversible expansion does not have a constant pressure so you use w=-nRTln(V2/V1). Irreversible expansion has a constant external pressure so you use w = -(Pex)dV

Abby Ellstrom 1I

Negative delta G signifies spontaneity while positive delta G reactions are not spontaneous.

Abby Ellstrom 1I

The change in enthalpy and entropy does not change between different temperatures in this equation so they can be treated as constant.

Abby Ellstrom 1I

There is work being done because W=PdeltaV and there is a change in volume therefore there must be a change in work as long as its not free expansion.

Abby Ellstrom 1I

Open system - exchange energy and matter
Closed system - exchange only energy not matter
Isolated system - cannot exchange energy nor matter

Abby Ellstrom 1I

The three ways include adding/subtracting matter from a system, adding or removing heat energy from a system, or applying work on or from a system.

Abby Ellstrom 1I

If you increase the volume of any substance, the entropy also increases. However the entropy of gas is much larger than that of liquids.

Abby Ellstrom 1I

Yes in open systems both energy and matter can be transferred. In closed systems only energy, but not matter, can be transferred. In isolated systems neither energy nor matter can be transferred.

Abby Ellstrom 1I

In isolated systems, no energy is transferred to the surroundings. In an adiabatic system energy is not transferred as heat to surroundings but as work.

Abby Ellstrom 1I

A closed system allows energy to be transferred but not matter. An isolated system allows neither energy or matter to be transferred.

Abby Ellstrom 1I

Is the only type of work used in this class the expansion work? There are lots of other types of work listed in a table in the textbook

Abby Ellstrom 1I

Can all combustion or burning reactions be treated as if they are in a bomb calorimeter?

Abby Ellstrom 1I

Why when a bond enthalpy for a molecule is greater than that of another one is the the molecule more stable?

Abby Ellstrom 1I

Are all bomb calorimeters isolated systems?

Abby Ellstrom 1I

Why is 25 degrees C the standard temperature for reactions? Does it matter if the initial temperature is not 25degrees C?

Abby Ellstrom 1I

What is the difference between extensive and intensive properties? Is this difference crucial to know for understanding the concepts?

Abby Ellstrom 1I

If enthalpy change is in terms of gaseous substances, how do you determine the enthalpy change in the dissociation of a liquid or solid?

Abby Ellstrom 1I

What causes a substance to superheat or supercool? Is this common?

Abby Ellstrom 1I

Why does molar heat capacity increase with molar complexity?

Abby Ellstrom 1I

What makes one base stronger than another? I understand the rules for acids but the base rules seemed unclear.

Abby Ellstrom 1I

Why is HF a stronger acid then HCl? I thought acid strength in this sense was determined by the electronegativity of the atom bonded to the H+ ion. Cl is more electronegative then F but on the homework it said that HF was stronger than HCl.

Abby Ellstrom 1I

Since the equilibrium constant does not change, when a question asks which way the reaction shifts, is that referring to the value of Q?

Abby Ellstrom 1I

How do you know what number of dentate a ligand is? Do you have to draw the lewis structure every time?

Abby Ellstrom 1I

Why does adding inert gases not change the pressure of the gas?

Abby Ellstrom 1I

I am very confused as how to find the percent decomposed of a reactant. When using the ICE table for this problem, I keep getting that PCL3 is 73% decomposed.

Abby Ellstrom 1I

Why when drawing the hybridized orbitals in Aufbau format is there sometimes an extra P-orbital above the hybridized ones?

Abby Ellstrom 1I

How do you know where to put the radical when drawing a lewis structure?

Abby Ellstrom 1I

Which two elements are the exceptions in the 3d sub shell?

Abby Ellstrom 1I

What is the difference between a sigma and a pi bond?

Abby Ellstrom 1I

Which M³⁺ ions (where M is a metal) are predicted to have the following ground-state electron configurations:
(a) [Ar]3d⁶
(b) [Ar]3d⁵

The answer to
(a) is Co³⁺
(b) is Fe³⁺

I am just very confused as to where these answers came from.

Abby Ellstrom 1I

Which M²⁺ ions (where M is a metal) are predicted to have the following ground-state electrons:
(a) [Ar]3d⁷
(b) [Ar]3d⁶

The answer to
(a) is Co²⁺
(b) is Fe²⁺

I am just very confused as to where these answers came from.

Abby Ellstrom 1I

Why is 'The effect nuclear charge Z_eff is independent of the number of electrons present in an atom." false?

Abby Ellstrom 1I

(a)How many values of the quantum number l are possible when n=7? (b)How many values of m_l are allowed for an electron in a 6d-subshell? (c)How many values of m_l are allowed for an electron in a 3p-subshell? (d)How many sub shells are there in the shell with n=4?

Abby Ellstrom 1I

How do you know if a wavelength indicates a particle has wavelike properties or not?

Abby Ellstrom 1I

I continue to get n=3.2 for this problem.

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?

Abby Ellstrom 1I

What is a good way to remember the categories of electromagnetic radiation?

Abby Ellstrom 1I

What do the energy levels conceptually mean or apply to (n=1,n=2,etc) when discussing the H-atom. How do the series names (Lymer, Balmer, etc) relate to anything?

Abby Ellstrom 1I

Allowing for an improper fraction in your balanced equation makes it easier when initially balancing the equation so you don't have to do it in your head. However, a final balanced reaction should contain no fraction stoichiometric coefficients so simply multiply the entire equation by the denominat...

Abby Ellstrom 1I

A student prepared a solution of sodium carbonate by adding 2.111 g of the solid to a 250.0-mL volumetric flask and adding water to the mark. Some of this solution was transferred to a buret. What volume of solution should the student transfer into a flask to obtain 4.98 mmol CO3^2- ion? I used the ...

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