To know this you pretty much do have to kind of memorize a few electronegativities. I don't recall ever getting a table of electronegativities on an exam.
From the structure, you have:
I remember the following electronegativities most because they are fairly patterned:
EN
H
=
2.1
EN
C
=
2.5
EN
N
=
3.0
EN
O
=
3.5
EN
F
=
4.0
EN
Cl
=
3.5
Notice how carbon through fluorine go in increments of
~
0.5
. I believe Pauling made it that way when he determined electronegativities in the '30s.
Δ
EN
C
−
Cl
=
1.0
Δ
EN
C
−
H
=
0.4
Δ
EN
C
−
C
=
0.0
Δ
EN
C
−
O
=
1.0
Δ
EN
O
−
H
=
1.4
So naturally, with the greatest electronegativity difference of
4.0
−
2.5
=
1.5
, the
C
−
F
bond is most polar, i.e. that bond's electron distribution is the most drawn towards the more electronegative compound as compared to the rest.
When the electron distribution is polarized and drawn towards a more electronegative atom, the less electronegative atom has to move inwards because its nucleus was previously favorably attracted to the electrons from the other atom.
That means generally, the greater the electronegativity difference between two atoms is, the shorter you can expect the bond to be, insofar as the electronegative atom is the same size as another comparable electronegative atom.
However, examining actual data, we would see that on average, in conditions without other bond polarizations occuring:
r
C
−
Cl
≈
177 pm
r
C
−
C
≈
154 pm
r
C
−
O
≈
143 pm
r
C
−
F
≈
135 pm
r
C
−
H
≈
109 pm
r
O
−
H
≈
96 pm
So it is not necessarily the least electronegativity difference that gives the longest bond.
Therefore, you cannot simply consider electronegativity. Examining the radii of the atoms, you should notice that chlorine is the biggest atom in the compound.
r
Cl
≈
79 pm
r
C
≈
70 pm
r
H
≈
53 pm
r
O
≈
60 pm
So assuming the answer is truly
C
−
C
, what would have to hold true is that:
The
C
−
F
bond polarization makes the carbon more electropositive (which is true).
The now more electropositive carbon wishes to attract bonding pairs from chlorine closer, thereby shortening the
C
−
Cl
bond, and potentially the
C
−
H
bond (which is probably true).
The shortening of the
C
−
Cl
bond is somehow enough to be shorter than the
C
−
C
bond (this is debatable).
Answer:
345.89 g/mol
Explanation:
To find the molar mass, find the atomic mass of all the elements from a periodic table.
Cs - 132.91 × 2 = 265.82
S - 32.07
O - 16.00 × 3 = 48.00
Now add them all together.
265.82 + 32.07 + 48.00 = 345.89 g/mol
Hope that helps.
<span>Mol is the unit of amount of substance. It is equal to 6.02 x 10^23 molecules. Now, One mol of Sodium chloride (NaCl) contains 6.022x 10^23 molecules of NaCl. Also, the number atoms of both Na (sodium) and Cl (chlorine) will be equal. Similatly, One mol of Aluminium Chloride (AlCl3) contains 6.022x 10^23 molecules of (AlCl3) but the ratio of Al and Cl atoms will be 1:3</span>
The answer would be a tenfold increase<span>
The pH scale is calculated based on the concentration of H+ ion in the solution. The formula is using log10, so to decrease 1 unit from the scale it will be 10^1= 10 fold of increase. For 2 </span>unit, you will need 10^2= 100 fold of increase.
