Chemistry Test #2 Flashcards
Buffered solution
- Resists change in pH
- Weak acids or bases with a common ion
What is the domain of Kinetics?
The reaction pathway, getting over the hill. Rate of reaction depends on the pathway from reactants to products. How fast the reaction is.
What does thermodynamics tell us?
Whether a reaction is spontaneous based only on the properties of reactants and products. How stable a reaction is.
What do thermodynamics allow us to predict?
The direction which a process will occur.
What is the common ion effect?
Same ions - eq shift bc of addition of ions already present in solution
What is the common ion effect an application of?
Le Chatelier’s Principle
What kind of solution makes up a buffer solution?
Weak acids + strong base
Strong acid + weak base
What are you adding when you add base
OH-
What are you adding when you add acid
H+
When does [HA] = [A-]
Half equivalence point
pH=pKa
What is the equivalence point for a strong acid and strong base?
pH = 7
What is q
Heat: transfer of energy between two objects due to a temperature difference.
What is w
Work: defined as a force acting over a distance.
Why can you only add small quantities to a buffered solution?
Large qualities overload one side and there is no longer equilibrium.
What happens when you add OH-
absorbs H+, less reactant causes a shift of equilibrium.
What does a lower pKa mean?
Lower pH, more acidic, stronger acid, higher H+
What happens if you increase the concentration of a aqueous solution that has a common ion with the reactant?
Solubility decreases.
What is the equation for Gibbs free energy?
∆G = ∆H - T∆S
∆H = Change in enthalpy
T = Temperature
∆S = Change in entropy (Disorder)
∆G = Gibbs Free energy
What is the equation for internal energy?
∆E = q + w
What does is mean if q is negative?
Exothermic
What does it mean if q is positive?
Endothermic
What does it mean is w is positive?
Surrounding does work on the system
What does is mean if w is negative?
System does work on the surroundings
What is the equation for work?
P x A x ∆h = P∆V
P = Pressure
A = Area
∆h = distance moved
What is the difference btw unsaturated and a saturated solution?
Saturated solutions cannot dissolve anything because of the solute can no longer dissolve. Unsaturated solutions can still dissolve the solute.
What is a ligand?
A lewis base: Electron pair donor
What is are complex ions?
Metal + non metal
What is quantitative analysis?
Analysis of a situation or event, especially a financial market, employing complex mathematical and statistical modeling.
When does precipitation occur with Q and Ksp?
Q > Ksp until the concentration is reduced to satisfy Ksp
When does precipitation not occur?
When Q < Ksp
What is the first law of thermodynamics and its implactions?
Energy cannot be created or destroyed
What is the second law of thermodynamics and its implications?
Any spontaneous process always causes an increase in entropy in the universe. The total energy is always constant. The entropy of the universe is always increasing.
S (Universe) = ∆S (system) + ∆S (surroundings)
Systems and surroundings are opposites.
What is enthalpy?
∆H = energy released or absorbed. tells if endo or exothermic.
What is entropy?
Measure of molecular randomness. The driving force of a spontaneous process is an increase of entropy in the universe. ∆S
Which way does positional entropy increase?
From solid to liquid to gas
What does more energy dispersal mean?
More entropy
What is the 3rd law of thermodynamics?
The entropy of a perfect crystal at 0 Kelvin is 0. entropy increases with temp.
What happens to the entropy in exothermic reaction?
Increase in entropy
What happens to the entropy in endothermic reaction?
Decrease in entropy
Why do particles arrange themselves as solids, liquids, and gases?
based on the energy levels and forces acting between the particles. movement and vibration.
How can large molecules in cells can be assembled from smaller ones without violating the law?
as long as other processes that force this to happen in the cell obtain a larger increase in entropy than the decrease in entropy by the creation of the larger molecule.
When liquids become vapor what happens and why?
Increase in entropy because more space to fill in the universe.
What qualifies a process to be spontaneous?
When ∆G is negative and when a reaction can occur without any assistance
How to know whether positional entropy decreases or increases?
look at the phases of the molecules if there is a gas it will favor the side with gas. If they are all in the same phase, look at the moles of each of the molecules.
How to know whether the reaction will occur in the forward direction by looking at a balanced equation?
By comparing the reaction quotient to the equilibrium constant,
What is the relationship between the number of hydrogen ions and anions produced by strong and weak acids?
Strong acids contain the same number of hydrogen ions and anions as the original dissociated strong acid molecule; weak acids contain far fewer hydrogen ions and anions than the original dissociated acid molecule.
What is the common ion effect?
The common ion effect is a shift in equilibrium position that results from adding an ion that is already present in the equilibrium reaction
How is the common ion effect useful in making buffer solutions?
Buffered solutions are simply solutions of weak acids or bases containing a common ion; the common ion effect is used to construct buffer solutions (they consist of a weak acid and a salt with a common anion to the acid).
Does Ksp ever change in different solutions
NOOOOOOO
How does concentration impact buffer capacity
A bigger concentration of buffer solution means a higher buffer capacity [HA] and [A-]
What happens if you put too much acid or base into buffer solution?
Kill the buffer
