Chem test 2 Flashcards
where do the most common and most important chemical reactions take place in?
Water
Define solution
homogeneous mixture of two or more substances
define solvent
major component of the mixture (water)
define solute
minority component of the mixture
how many carbons in an alcohol does it take to become insoluble in water?
5 carbons
What does the solubility of one substance in another depend on?
intermolecular forces (like dissolves like)
- between the solvent and solute
-between the solvent particles
-between the solute particles
More polar substances dissolve better in water because water is polar
define saturated
the point where the max amount of solutes have dissolved. if you add more they won’t dissolve
define unsaturated
a solution in which the solvent holds less than the max solute. if you add more they will dissolve
define supersaturated
a solution in which the solvent holds more than the max amount of solute dissolved (usually unstable)
this happens if you heat a saturated mixture and add more solute. when it is cooled it will stay dissolved and be supersaturated
How to find the molecular weight of something
add the mass of each atom in your compound
How to calculate for mols
Mass of sample (g) / molecular weight (g/mol)
How many moles are in a 10g sample of water? molecular weight is 18.02
10g/18.02g/mol = 0.555mol
Density equals
mass over volume
how to describe the amount of solute in a solution by molarity:
mol/L
how to describe the amount of solute in a solution by weight percent:
mass/mass X 100%
how to describe the amount of solute in a solution by volume percent:
volume/volume X 100%
a solution concentration expressed in moles of solute/kg of solvent will be presented as _____
This type is independent of ______ but can change depending on the ________ of the solvent
weight/weight
independent of temperature but can change depending on the density of the solvent
What is the process to solve for a molality weight weight problem?
g (solute) -> moles (solute) -> molality (solution)
When is the weight percent useful?
When the solute is a solid
define weight percent
solution concentration expressed as a percentage of the solute mass in the mass of solution
define volume percent
solution concentration expressed as a percentage of the solute volume in the volume of the solution
When is the volume percent useful?
when the solute is a liquid
how much ethanol is in a 10mL sample of 85% aqueous ethanol?
(85mL/100mL) X 10mL
how much NaCl is in a 25g sample of 0.900% saline solution?
(0.900g NaCl/100G) X 25g
