General Chemistry 2 Flashcards
(51 cards)
What do solutions contain?
Solute and solvent
What is crystallization?
Dissolved solute comes out of a solution and forms crystals
How you increase solubility of solids, liquids and gases?
Solubility of liquids and gases increase with increasing temperature usually. Solubility of gases increase with decreasing temperature and increasing pressures
What is percent composition?
Mass of solute/ mass of solution x 100%
What is mole fraction?
X moles of B/ sum of moles of all components
What is molarity?
Number of moles of solute/ liter of solution
What is molality?
Number of moles of solute/ kilogram of solvent
What is Normality?
N = molarity x equivalents/ mol
What is the equation for dilutions?
C1V1= C2V2
What is an electrolyte?
Solutes that make conductive solutions
What makes a strong electrolyte and what are examples of strong and weak electrolytes?
A solute is considered a strong electrolyte if it dissociates completely into its ions.
Strong electrolytes: NaCl, KI, HCl
Weak electrolytes: Acetic acid, ammonia, weak acids and bases, HgCl2
What are non electrolytes and what types of molecules fall under this category?
Don’t ionize at all in aqueous solution, retain their molecular structure in solution, e.g. non polar gases and organic compounds (oxygen and sugar)
What are the 4 basic reaction types?
Combination reactions, decomposition reactions, single displacement reactions, double displacement reactions
What happens during oxidation reduction reactions?
Transfer of electrons, oxidation (loss of electrons) and reduction (gains electrons)
What happens to oxidizing and reducing agents?
- Oxidizing agent causes atom to undergo oxidation and itself is reduced
- Reducing agent causes other atoms to be reduced and is itself oxidized
How do you balance redox reactions?
Have to balance Net charge and number of atoms!
Steps:
1) separate 2 half reactions
2) balance the atoms of each half reaction, add H2O or H+ to balance h and O
3) Balance the electrons of each half reaction
4) Combine the half reactions
5) confirm the mass and charge are balanced
6) for basic reactions add OH- to neutralize the H+
What cells do spontaneous and non-spontaneous reactions occur in?
Spontaneous reactions occur in galvanic cells and non-spontaneous reactions in electrolytic cells
Does oxidation/reduction occur at the anode or the cathode?
Oxidation occurs at the anode
Reduction occurs at the cathode
What is the structure of a galvanic cell?
- Supply energy and used to do work
- Oxidation and reduction half reactions in separate containers called half cells connected by a wire or conductor
- Usually salt bridge used
What is the structure of the electrolytic cells?
- Oxidation and reduction half reactions placed in same container (no salt bridge required)
- Usually have battery or power source to drive the non spontaneous redox reaction
Concerning anodes and cathodes: which direction do electrons flow?
Electrons always flow from ANODE to CATHODE
What is the anode of an electrolytic and galvanic cell considered?
Anode of electrolytic cells is considered positive but anode of galvanic cell is considered negative
What is the equation for number of moles of electron transferred by an electrochemical cell?
i x t = n x F
Where i is current, n is number of moles of electrons, t is time in seconds, and F is faradays constant 96487 C (or J/V)
What is the reduction potential?
Tendency of a species to acquire electrons and be reduced, more positive value is the greater the tendency to be reduced, measured in volts
