chem pr
Terms
undefined, object
copy deck
- substance present in the small proportion in a solution
- solute
- substance present in the greatestproportion in a solution
- solvent
- process that occurs when the solvent molecules surround the solute molecules
- solvation
- if the solvent is water for solvation, what is the process called?
- hydration
- (t/f) solutions can involve any of the three phases of matter
- true. can have a solution of two gases, solid in a solid (alloy), solid in a liquid, etc.
- what is a solid in a solid solution called?
- an alloy.
- when a solution has water as the solvent, what kind of solution is it called?
- aqueous
- what is a saturated solution?
- one in which no more solute will dissolve; at this point we have reached the molar solubility of the solute for that particular solvent.
- what is the reverse process of dissolution
-
precipitation;
occurs at the same rate as dissolving; both the solid form and the dissolved form are said to be in dynamic equilibrium. - solubility
- refers to the amnt of solute that will saturate a particular solvent.
- (T/F) Solubility is specific for the type of solute and solvent.
- True.
- (T/F) Solubility varies with temperature, increasing or decreasing with temperature depending upon the solute and solvent.
- True;
- The solubility of most solids in liquids (increase/decrease) with increasing temperature.
- True.
- The solubility of most gases in liquids (increases/decreases) with increasing temperature.
- decreases
- Molarity (M)
- (# of moles of solute) / (# liters of solution)
- Electrolytes
-
free ions in a solution;
called this b/c the solution can conduct electricity. - strong electrolytes vs. weak electrolytes vs. non-electrolytes
-
- strong: dissociate completely
- weak: remain ion-paired.
- non-electrolytes: covalent compounds that don't dissociate into ions. - (T/F) Solutions of strong electrolytes are better conductors ofe lectricity those of weak electrolytes.
- True.
- van't Hoff(or ionizability) factor
- tells us how many ions one unit of a substance will produce in solution.
- What is the van't Hoff factor of C6H12O6?
- it's non-ionic so it doesn't dissociate; thereby, i =1.
- What is the van't Hoff factor for almost all biomolecules -- hormones, proteins, steroids, etc.?
- 1
- What is the Van't Hoff Factor of NaCl?
- It dissociates into Na+ and Cl-; therefore, i=2.
- What is the Van't Hoff Factor of HNO3?
- this dissociates into H+ and NO3-; therefore, i=2.
- What is the Van't Hoff Factor of CaCl2?
- It dissociates into Ca2+ and 2Cl-; therefore i=3.
- Covalent Bond
- formed btw atoms when each contributes one of itsunpaired valence electrons.
- (T/F) Electrons in d subshells are not considered valence electrons when writing Lewis dot symbols.
- True.
- What will tell you if the atoms are sharing their electrons in the "best" way possible?
- - the formal charge (the best structure is the one that minimizes the magnitude of the formal charges.)
- Formal charge formula
- V-0.5B-L where V is the number of valence electrons, B is the number of bonding electrons, and L is the number of lone pair (non-bonding electrons).
- What should you do first whenever trying to see what the best Lewis structure is?
- Simply count up all the electrons and see if it matches.
- (T/F) Resonance structures are two or more sturcutres where only nonbonding electrons, and double and triple bonds may move around.
- True.
- polarity
- molecule is partially negative (denoted by delta negative) and partially positive (denoted by delta positive)
- A bond is polar if...
-
- the electron density between the two nuclei is uneven;
- if there is a different in electronegativity. - Is CCl4 polar or nonpolar?
- Its non-polar because the four polar bonds are symmetrically arranged leaving the molecules as a whole nonpolar, with no dipole moment.
- Is O=C=S polar?
- Yes; although C=O is more polar than the C=S giving a net dipole moment in the C=O direction.
- Coordinate covalent bond
- when one attom donates both of the shared electrons in a bond; such as the lone pair on boron of NH3.
- Lewis base
-
aka. ligand
electron pair donator. (SUch as NH3) - Lewis Acid
- electron pair acceptor; such as BF3
-
Whcih one of the following anions cannot behave as a Lewis base/ligand?
a. F-
b. OH-
c. NO3-
d. BH4- - Must have a pair of nonbonding electrons to be a candidate Lewis base/ligand ==> choice D doesn't have any nonbonding electrons.
- (T/F) Carbon atoms with nonbonding electrons are excellent Lewis bases/ligands.
-
True;
Ie. CO, -CN, and -CH3 are all good lewis bases while CO2 is not. - For an ionic bond to form btw a metal and a non-metal, what has to be pressent?
- a big difference in electronegativity between the two elements.
- Which is stronger ionic bond: MgO or NaCl?
-
- For MgO, we have PE prop (+2)(-2)/r while for NaCl we have PE prop (+1)(-1)/r.
- Note that these PE are negative ==> ionic system is more stable than the ions separated from each other.
- Ratio of these potential energies is -4/-1=4 - (T/F) Hydrogen is considered an alkali metal.
-
- False!
- hydrogen itself is not considered to be one of the alkali metals. Its place in the table does make sense, though; hydrogen tends to behave like the other members of its column in chemical reactions. For example, all these elements combine with oxygen to form compounds with the formula X2O.