Exam 3 Flashcards
What helps properties mix when substances do not form a solution?
Surfactants
What is an example of a surfactant?
Dish soap helping water and oil mix
What is a solute?
In a solution, a solute is the thing that gets dissolved
What is a solvent?
In a solution, the solvent is the the liquid/substance in which the solute dissolves
The interaction between solute and solvent is called… If the solvent is water it is called…
Salvation, Hydration
For something to be a true solution, it must be
A homogenous mixture
In hydration, what type of bonds typically allow ions to stay intact?
Covalent
In hydration, which type of bonds allow ions to break apart?
Ionic
When is a solution saturated?
When no more can dissolve
What happens if we add solute to a saturated solution?
It will no longer break apart and dissolve, it’ll sink to the bottom
What is equilibrium?
When two opposing forces work together at equal rates
How is a saturated solution at equilibrium?
It is a back and forth process where some things go into the solid clump and some leave
What happens to solubility as temperature increases? What is an exception?
As temperature increases, solubility increases (except for gases).
Generally, what are the rules for soluble substances?
All group 1 metals =soluble (no exceptions) Ammonium NH4+ = always soluble Nitrate NO3- = always soluble Acetate CH3COO- = always soluble Perchlorate ClO4- = always soluble Chlorate ClO3- = always soluble
Generally, what are the rules for insoluble substances?
Carbonate = insoluble (except when combined with no exception compounds
If we have a displacement reaction, how do we predict equations?
the reactants will switch partners when they become products
What is a complete ionic equation?
In this type of formula, we only write aqueous solutions as each individual ion, non aqueous solutions are written as a whole
ex: AgNO3 turns to Ag+ (aq) + NO3- (aq) BUT AgCl (s) stays intact
What is a net ionic equation?
From a complete ionic, those that changed in the reaction, get to be written. Those that stayed the same are not included and are called spectator ions.
ex: Ag+ + Cl- –> AgCl so, we would write AgCl in the net ionic
How can we describe solution concentration?
Concentration = (amount of solute)/(amount of solvent)
In a concentration problem, if we are asked for w/w or m/m, what are the units?
grams/grams
If it is v/v what are the units?
mL/mL
If it is w/v, what are the units?
g/mL
What is molarity?
moles/ liters
What is a dilution?
the process of decreasing the concentration of a solute in a solution, usually simply by mixing with more solvent like adding more water to a solution.
ex: adding more water to a salt-water solution making it less salty
In a dilution, what is constant? what changes?
In a dilution, concentration is reduced and amount of solute is constant
How can we use moles (the constant) as a conversion factor?
M1V1=M2V2
What is diffusion?
Diffusion describes the movement of particles from areas of high concentrations to low concentrations
Is diffusion faster in gases or solutions?
Diffusion is faster in gases because they are interacting with empty space. In solutions, they interact with solvent
What is osmosis?
It is a type of diffusion that has a semipermeable membrane where solvent can move (solute cannot)
Why does the solvent move in osmosis?
Water (and other solutions)have a tendency to equalize concentration on both sides of the membrane.
What is hydrostatic pressure?
This type of pressure occurs when the side with the most water creates pressure by weighing and pushing down the water.
How is osmotic pressure calculated?
osmotic pressure (π) = i (n/v) R T where i(n/v)= moles
What is the i in osmotic pressure?
It accounts for the number of particles where single elements count as one and polyatomic ions count as one.
ex: NaNO3= Na+ and NO3- i= 2
In cells, what is a hypotonic?
This occurs when there is a low concentration outside the cell so water moves in and the cell blows up
What is hypertonic?
This occurs when there is a high concentration outside of cell so water moves out of it leaving it deflated.
What must occur for a reaction to happen?
- molecules must collide with enough energy
- molecules must collide in the correct orientation
What factor would make it more likely for molecules to collide with enough energy?
heat
What is the activation energy?
the minimum quantity of energy which the reacting species must possess in order to undergo a specified reaction.
What does a forward reaction look like?
A+B -> Activated complex (spark) -> C+ D
What does a backwards reaction look like?
C+D -> Activated complex -> A + B
In a forward reaction, what is the heat energy?
Since the graph shows the products lower than the reactants, we can assume heat is being released AKA exothermic
In a backwards reaction, what is the heat energy?
Since the graph shows the products higher than the reactants, we can assume heat is being absorbed AKA endothermic.
How can we calculate the heat energy produced between 2 reactions?
We can take the difference in activation energy by subtracting the one from a forward reaction minus the Ea of a backward reaction.
What happens to reactants and products as a reaction advances?
As a reaction continues, reactants decrease and products increase.
What formulas can we use to describe the rate/relationship between reactants and products?
appearance of product/time OR
disappearance of reactant/time
What is the purpose of a catalyst?
To speed up the rate of the reaction (reaction remains unchanged but the shape (graph) of the reaction changes
What happens to the activation energy when a catalyst is applied?
It is lowered
What is a reaction intermediate?
is a short-lived, high-energy, highly reactive molecule. When generated in a chemical reaction, it will quickly convert into a more stable molecule
What is the difference between a reaction intermediate and a catalyst?
A reaction intermediate is produced early and consumed later. A catalyst is consumed early and produced later. Both are not present in the overall reaction
How do we identify intermediates and catalysts?
Reaction sequences
How do reaction sequences function?
First, look for the elements that appear either first in reactants and then in products or first in products then reactants. Once you identify them, if the element is in the reactants (first step) and products second step, it is a catalyst. If it is in the product first step and reactants second step, it is an intermediate
How is equilibrium represented?
With a double arrow
How do we find the value for constant concentration of products and reactants?
Since the concentration of products and reactants is constant at equilibrium, the value for this can be calculated by Keq = products/reactants
Only constant at a given temperature