Resolved Question

Chemistry question- general organic?
Explanation of inductive effect and how it effects acidic behaviour??

by joeyeehu...
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Inductive effect can be divided into two types, positive inductive and negative inductive.A group or atom is said to have a positive inductive effect if it tends to push away electrons away from them(electron donating group). I will increase the electron charge density of its neighbour. Example of such group is the alkyl group ( CH3, C2H5 ).Electron withdrawing group will attract the electrons toward itself (negative inductive effect), ex. F, Cl, NO2. They will reduce the electron charge density of the O--H bond. This will weaken the O--H bond and the molecule is able to donate the H+ more easily. It increases acidic behaviour. ( acid is a proton(H+) donor )

Why does oxygen is a gas but sulphur a solid?

joeyeehu...

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The melting and boiling points of a substance will determine whether it will exist as solid, liquiq or gas at room temperature.

A substance with high melting and boiling points usually exists as solid at room temperature.

Oxygen exists as a diatomic molecules whereas sulphur exists as S6.
Both oxygen(O2) and sulphur(S6) are non polar molecules. Between the molecules, there are intermolecular forces of attraction(IMFOA). This IMFOA is called van der Waals forces. The strength of van der Waals forces depends on the size of the molecules. Since S6 molecules is larger than O2 molecules, the v.d.W forces between the S6 molecules is stronger than that between the O2 molecules, the melting point of sulphur is higher than that of O2. Hence sulphur exists as solid and O2 exists as gas( it has a very low melting and boiling point)

What is the formulas of the conjugate bases of the following Bronsted-Lowry acids.?

(a) HClO4
(b) H2PO4-
(c) HCN

joeyeehu...

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A conjugate base of an acid is the species formed when one proton(H+) is removed from the acid.

a) ClO4-

b) HPO42-

c) CN-

Help with this tough AP Chemistry Problem?

N2(g) + 2O2(g) <-->N2O4(g)

If the value of the equilibrium constant with regard to pressure (Kp) is found to be 1.5 at 15°C, what is the value of the eqilibrium constant with regard to concentration?
(R = 0.0821 L•atm/(mol•K))



a. 8.4 x 102
b. 2.3
c. 9.4 x 107
d. 2.7 x 10–3

joeyeehu...

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Assume that the unit of Kp is atm-2.

Kp = Kc ( RT) ^ -2

Substitute the values into the equation, (a) is the answer.

T= 15 + 273 K
-2 is the number of moles of the products minus the number of moles of ractants. ( 1 - 3 = -2 )

I got a question about aluminum- tough AP chemistry problem...?

The Hall-Héraoult process for the electrolysis of aluminum oxide uses the mineral substance, cryolite (Na3AlF6), which of the following is not a reason for using cryolite?
a. Aluminum oxide dissolves in molten cryolite.
b. Molten cryolite is able to conduct an electrical current.
c. The aluminum in cryolite serves a a nucleation site for the reduction reaction.
d. Cryolite melts at a much lower temperature than aluminum oxide, thus lowering the energy costs of the reduction process.

joeyeehu...

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c

What is the concentration of Bi3+ in a saturated solution containing .01M S2-? Ksp bismuth sulfide=10^-70?

Ksp = [Bi3+]^2 [S2-]^3 ... I am wondering why do we need the Ksp if we know the ratio of Bi ions to S ions is 2:3... maybe I am misunderstanding this question.

joeyeehu...

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Bi2S3 <========> 2Bi3+ + 3S2-

Ksp = [Bi3+]^2 [S2-]^3

Substitute the value of Ksp = 1 x 10^-70
................................[S2-] = 0.01
.{ assume that the conc. of Bi3+ that originate from the dissociation of Bi2S3 is negligible}

1 x 10^-70 = [Bi3+]^2 (0.01)^3

[Bi3+] = 1 x 10^-32

Energy Levels and Orbitals:?

What is the relationship between energy levels and orbitals?

joeyeehu...

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Energy levels can be associated with the electron shells or the principal quantum numbers. The higher the number the higher the energy levels.

Each principal quantum number (n) can have a certain orbital.

For n = 1, there is only one type of orbital namely s orbital
For n = 2, there are s orbitals and p orbitals where the p orbitals are of higher energy than s orbitals

For n = 3 -> s , p and d orbitals

and so on.

Although the rule says that the higher the principal quantum number the higher the energy level, there are a few exceptions. Ex. 4s orbital is lower in energy than 3d orbital.....