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Apologia Chem M10
The Chemistry of Solutions
Question | Answer |
---|---|
solute | substance being dissolved |
solvent | substance IN which the solute is being dissolved |
solution | created when a solute and a solvent are mixed together |
NaCl is a ionic compound, and ionic compounds do NOT have | chemical bonds. The atoms DONATE or RECEIVE electrons, they do not share electrons. |
The ELECTRONIC ATTRACTION between opposite charges is | the ONLY THING that holds IONIC COMPOUNDS together. |
Water is a POLAR covalent compound, meaning it has | a FRACTIONAL positive charge on its hydrogen atoms & a FRACTIONAL negative charge on its oxygen atoms. |
NON-POLAR covalent solids | do NOT dissolve well in water because they have NO electrical charges in them. |
POLAR covalent solids | CAN dissolve in water because they DO possess fractional charges. |
Polar covalent molecules dissolve in water, but they do NOT | split into smaller parts. |
Ionic compounds dissolve by | breaking apart into their individual ions. |
Polar covalent compounds dissolve by | separating each individual molecule from its neighbors. |
In the SOLID phase, the solvent molecules must be attracted to the solute molecules so STRONGLY that | the solvent molecules can get BETWEEN the solute molecules (or ions) and pull them FAR APART from each other. |
In the LIQUID phase, the solvent molecules need to be attracted to the solute molecules only a SMALL amount because the solvent | does NOT need to separate the solute molecules VERY MUCH. |
In the GAS phase, the solvent molecules must be attracted to the solute molecules enough | to pull the solute molecules CLOSER to one another. |
solubility | the maximum amount of solute that can dissolve in a given amount of solvent |
The solubility of any solute depends on both the identity of the solute & the identity of ___________________________. | the solvent |
saturated solution | a solution in which the maximum amount of solute has been dissolved |
precipitation | the process by which a solute leaves a solution and turns back into its solid phase |
The solubility of SOLID solutes usually | INCREASES with INCREASING temperature. |
The solubility of LIQUID solutes is | NOT affected by temperature. |
The solubility of GAS | DECREASES with INCREASING temperature. |
Increasing pressure | INCREASES the solubility of GASES. |
Pressure | does NOT affect the solubility of liquids or solids. |
exothermic | a process that LETS OUT heat |
endothermic | a process that ABSORBS heat |
Most solids dissolve in an ____________________ manner; they must absorb energy to dissolve properly. | endothermic |
molality | the number of moles of solute per kilogram of solvent |
FORMULA for molality | m = (# moles solute)/(#kg solvent) |
When calculating MOLALITY, we are concerned with | MASS, not volume. |
When calculating MOLALITY, we divide only by the mass of the | SOLVENT - NOT by the mass of the solution. |
freezing point depression | when a solute is dissolved in a solvent, the freezing point of the solution will be LOWER than that of the pure solvent |
boiling point elevation | when a solute is dissolved in a solvent, the boiling point of the solution will be HIGHER than that of the pure solvent |
Kf | freezing point depression constant |
Kb | boiling point elevation constant |
i | number of molecules or ions that a solute splits into when it dissolves |
A NEGATIVE sign in a temperature change equation means | that the temperature DROPPED. |
melting point | another name for freezing point |