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Here is the answers to 2022-2023 Chem328 Review HW for Polarity, IMF and Physical Properties including Solutions, Molarity.
2) Using Molecular Polarity table:
- CCl4, ΔEN =0.5, 4 non-polar bonds, Tetrahedral (sym), NA, non-polar molecule, LDF
- BeCl2, ΔEN =1.5, 2 polar bonds, Linear (sym), Yes, non-polar molecule, LDF
- CS2, ΔEN=0.0, 2 non-polar bonds, Linear (sym), non-polar molecule, LDF
- NF3, ΔEN=1.0, 3 polar bonds, Pyramidal (not sym), polar molecule, dipole-dipole
3) Made mistake, no question/problem
4)+-->, Arrow over the more electronegative atom (or whatever way you memorize the symbol).
5) Ionic ΔEN> or = 1.8
polar bond is 1.8<ΔEN> or >0.4
6) Ionic compound/bond same strength as metals/metallic bonds (Highest IMF)
Polar molecules containing H-O,H-N,H-F (IMF name is hydrogen bonding)
Polar molecules that don't (IMF name is dipole-dipole interaction)
Non-polar molecules (IMF is London Dispersion Forces, LDF) (Lowest IMF).
7) Dipole-dipole interactions and Hydrogen bonding
8) True, (LDS are only major IMF for non-polar - non-polar molecules interaction and two substance with very large difference in molar mass (# of electrons).
9) No, polar or non-polar is for covalent (sharing) bonds
11) H2O1 would have higher IMF since both have Hydrogen bonding IMF but H2O1 has two Hydrogen bonding.
Ethanol (name of CH3CH2OH) has lower IMF strength so it will boil first (i.e. has lower boiling point.
12) Distillation is a physical separation based on boiling/boiling point. Boiling is based on CF, London dispersion forces (LDF). Octane has a higher IMF since it a higher molar meaning more electrons so more Instantaneous dipoles. So since IMF is higher, it will take more energy (higher boiling point) so boiling first means lower boiling point (Hexane).
13a) 2.0 mole Cl1-
13b) 1.0 mole Ca2+
13c) 3.0 mole of ions, since each Ca1Cl2 (called formula unit) is actually made up of 3 ions ratio.
13d) See your notes or class notes on how dissolving ionic compound looks like in solution.
14a) 1.0 mole C1O1 molecules. Since it is a molecular compound it base units, molecules, have all ve<sup>-</sub> being shared to group of atoms stay together as a single base unit.
14b) See your notes class notes on dissolving polar solute in polar solvent.
15) H2O1 is a polar molecule and oil is a hydrocarbon (CxHy) a non-polar molecule. So H2O1 exerts coloumbic force (CF) while oil does not. So H2O1 molecules are interacting with other H2O1 molecule so they will "push oil molecules" around so they will be together. See your figure in your notes or class notes/handouts
16a) unsaturated solution
16b) Saturated solution
16c) No more solute can be dissolved in the solution (since it is saturated) so solute creates a separate layer/phase either above saturated solution below (location of not dissolved is base on density but density has nothing to do that there is solute that be dissolved any more).
17a) Solvent particles have more energy so they each molecule occupies more space so there is more empty space between solvent particles.
17b) With more empty space between solvent particles, you put more solute (dissolve more) in solution (can see that from class note Solubility curve).
17c) With more empty space between solvent particles, more solute particles, that are in gas phase, can "escape" out of the solvent/solution (can see that from class note Solubility curve).