Which of the following contains an sp2-hybridized carbon?

CH4
CH3:-
CH3CH3
CH3+
HC(triple bond)CH

joeyeehu...

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It is CH3+

There are 3 pairs of electrons around the carbon atom.
This suits the sp2 hybridised orbitals of carbon and it will take the shape of trigonal planar.

CH3- is not sp2 hybridised. It is sp3 hybridised.
There are 4 pairs of electrons around the carbon atom.
Although it is sp3 hybridised, the shape is trigonal pyramidal because there is a lone pair of electrons.

What is the best lewis structure of CLF2+?

joeyeehu...

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First, calculate the total number of electrons around the central atom, that is Cl.

Cl - 7e
2F - 2e ( F is the terminal atom, so each atom will contribute one electron )

The total is 8e as you have to minus one electron because of the one positive charge.

So, there a a total of 8 electrons around the central atom Cl. ( 4 electron pairs)

The 4 electron pairs will be placed as far apart as possible around the Cl atom. Tetrahedral arrangement is the most likely geometry.

Out of the 4 electron pairs, 2 of them will be the bond pairs ( forming bonds with F in Cl-F) and the other 2 will be the lone pairs.

Hence, the Cl atom will be surrounded by 2 lone pairs and 2 bond pairs of electrons and it will take the shape of 'V' or bent.

The Lewis structure:

[:F- Cl - F:]+

* There will be two dots each at the bottom and above the F-Cl-F
* For your information, F can only form one bond.

Difference between relative ISOTOPIC mass and relative ATOMIC mass?

Can anyone tell me is there any difference between relative ISOTOPIC mass and relative ATOMIC mass???

In my class they are introduced separately, but it seems like they are same when I read some other textbooks/reference.

Besides difference, how are they similar to each other??

Please don't copy the paragraphs in Wikipedia "Atomic Mass".........

Thanks.

Additional Details

so, do they refer to the same thing or just different??

and... what is RIM?

joeyeehu...

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Most natural occurring elements can exist in a few isotopic form. Some has two, some has three and some has six ....ect.

For example, chlorine can exist as two isotopic forms, namely chlorine-35 and chlorine-37.

We can say that the relative isotopic mass of chlorine-35 is 35 and the relative isotopic mass of chlorine-37 is 37.

To determine the relative atomic mass of chlorine, then you must know the relative abundance of isotope Cl-35 and that of isotope Cl-37.

It is found that the relative abundances of Cl-35 and Cl-37 are 75% and 25%.

The relative atomic mass of Cl is the weighted average of the relative isotopic mass of Cl-35 (75%) and the relative isotopic mass of Cl-37 (25%).

So, relative atomic mass of chlorine ={ (75 x 35) + (25 x 37) } / 100
......................................… 35.5

So, RIM of element X refers to the relative mass of a particular isotope only.
RAM of element X refers to the average relative mass of all isotopes of X.

Solution Vapour Pressure and Vapour Composition?

A) At 25°C the vapour pressure of pure pentane is 511 torr and that of hexane is 150. torr.
What is the mole fraction of pentane in a pentane-hexane solution that has a vapour pressure of 387 torr at 25°C?

B) What is the mole fraction of hexane in the vapour that is in equilibrium with this solution?
(Assume ideal gas behaviour.)

• e

joeyeehu...

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(A) Using Raoult's Law,
The vapour pressure of pentane = mole fraction of pentane(liquid) x pure vapour of pentane
P (p) = X (p) x 511 .................(1)

The vapour pressure of hexane,

P (h) = X (h) x 150 .................. (2)

(1) + (2):

P (p) + P (h) = 511 X(p) + 150 X(h) ..................(3)

Given that the total pressure P(t) = P (p) + P (h) = 387 and
mole fraction, X(h) = 1 - X(p)

Substitute into equation (3),

387 = 511 X(p) + 150 ( 1 - X(p) )
387 = 511 X(p) + 150 - 150 X(p)

X(p) = 0.657

(B)
From equation (1), the vapour pressure of pentane:
P(p) = 0.657 x 511 = 335.7 torr

Mole fraction of hexane in liquid = 1 - 0.657 = 0.343
From equation (2), the vapour pressure of hexane :
P(h) = 0.343 x 150 = 51.5 torr

Using Dalton's Law of Partial Pressure,
Mole fraction of hexane in the vapour = partial pressure of hexane / total pressure = 51.5/387 = 0.133

»

Chemistry question about hydrogen ?

why do hydrogen always forms co-valent bond. it has one electron so it can easily donate and form ionic bond

• 3 years ago
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Additional Details

i was this may be because every chemical bond happens to get octet(8 valence electrons) or duplet(2 valence electrons).so if it gives one electron then it will not achieve duplet .so it forms co valent bond to achieve it.

3 years ago

this may be because every chemical bond happens to get octet(8 valence electrons) or duplet(2 valence electrons).so if it gives one electron then it will not achieve duplet .so it forms co valent bond to achieve it.

3 years ago

joeyeehu...

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If the hydrogen atom combines with metals, it will form ionic bond in the form of hydride. Example NaH.

With non metals, it will share its electron to form covalent bond. All depends on the difference in the electronegativities between H and the other atoms. If the difference is very big, then ionic bond. If the difference is small, then it forms covalent bonds

Chemical reaction question?

Can someone help me with this problem?
44.3 grams of C6H6 reacts with 122.4 grams of O2. How much CO2 will be produced by this reaction?
2C6H6 + 9O2 -> 6CO2 + 6H2O

• 3 years ago
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joeyeehu...

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Number of moles of C6H6 = 44.3/78 = 0.568 mol
Number of moles of O2 = 122.4/32 = 3.825 mol

C6H6 is the limiting reactant because 0.568 mol of C6H6 needs
9/2 x 0.568 = 2.556 mol of O2 to react.

There are 3.825 mol of O2 available. So O2 is in excess.

Hence, the number of moles of CO2 produced = 6/2 x 0.568 mol
......................................… 1.704 mol of CO2
......................................… 74.98 g of CO2

If the experiment is carried out at room temperature, then the volume of CO2 produced = 1.704 x 24 dm3 = 40.90 dm3

Which molecule is the strongest base?

Ethylamine
Propylamine
Aniline
Dipropylamine
Methylamine

joeyeehu...

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Alkyl group will increase the basicity of amine. Alkyl group is an electron-releasing group. It will increase the electron charge density of the nitrogen atom of the amine group(NH2). This makes the lone pair of electrons of the nitrogen atom to be easily available to be donated to a proton. (to accept a proton) and hence increase its basicity.

The larger the alkyl group, stronger is the releasing power and the higher is the electron charge density of the nitrogen atom.

Since dipropylamine consists of two propyl groups, its positive inductive effect(electron releasing effect) is the greatest and is the strongest base