destroyer q's

[queenskillers]

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in q 120 in gen chem section, shouldnt you multiply the bond energies by the number of bonds?

can someone also elaborate on q 112 in gen chem. how is h20 formed and etc.

in q79 gen chem, how can ethers and h20 be misicible when ethers dont even hydrogen bond?

in q 84 gen chem, what are the exceptions to the normal ground state rules since cu and cr dont seem to follw them?

 

[moralbrain]

in q 120 in gen chem section, shouldnt you multiply the bond energies by the number of bonds?

can someone also elaborate on q 112 in gen chem. how is h20 formed and etc.

in q79 gen chem, how can ethers and h20 be misicible when ethers dont even hydrogen bond?

in q 84 gen chem, what are the exceptions to the normal ground state rules since cu and cr dont seem to follw them?

In Destroyer, it says ether and water are miscible, while same kind of problem from Topscore says they are not miscible.😕 Ether has oxygen (electronegative) and it can make the molecule a bit polar, and we all know water is polar. Since they both are polar, they are miscible (also hydrogen forms between electropositive hydrogen and lone pair of electronegative atom). My understanding was Topscore would say they are not miscible because it is only slightly miscible (when you increase the amount of ether in the mixture, it starts to form two diff layers, less dense ether on top), while Destroyer says they are miscible because they are actually miscible up to some point.
Correct me if I am wrong here..

 

[TheWiredNerv]

You're right moralbrain. Ether and water are miscible to a point. Try recalling all the organic chemistry labs you've been through and you'll realize that this is so.

For g chem 120 the formula is Sum of Bonds Broken - Sum of Bonds formed.
If you look carefully the only bonds being broken on reactants is 1 C-H bond and 1 Br-Br bond. Thus on the products side you have a C-Br bond forming and a H-Br forming. When you do the calculations you can just use these 4 bonds to determine the overall energy.

For questions like 84 you have to look at the electron configuration. Cu doesn't follow the trend because it has 9 electrons in the d subshell so to become more stable, 1 electron will move from the 4s to the d and will become 4s1 3d10.
Cr is the same thing. It is more stable to have two subshells half full then one subshell full and the other not full. 4s2 3d4 vs 4s1 3d5, the later contains a half filled 4s and 3d making it more stable than a full 4s and partially filled 3d.

Hoped this helped.