Unit 4 & 5: Solution Stoichiometry and Thermochemistry Flashcards
Definition of solution
A homogeneous mixture of two substances
What are the two parts of a solution?
- Solute
2. Solvent
Definition of solute
The substance which gets dissolved
Definition of solvent
The substance which does the dissolving
What is the solute usually like? (physical features)
- usually the smaller amount
- usually a solid (not always)
What is the solvent usually like? (physical features)
- larger amounts
- usually a liquid
Definition of concentration
The amount of solute dissolved in a given amount of solvent
“the greater amount of solute dissolved in a given amount of solvent; the greater the concentration”
Definition of molarity
what is its symbol
a way to quantify concentration in chemistry
symbol: M (capital)
What is the equation for molarity?
M= (moles of solute) / volume (L) of solution
Definition of dilution
Reducing the concentration of a chemical solution
What is the main method of diluting?
Adding water
How do you mix a solute into a solution?
Pour half of the solution into the beaker, then add the solute, then add the rest of the solution
Which is poured first, water or acid?
you pour acid into water…ALWAYS!
What is the equation that is used when you are trying to find the initial molarity, initial volume, final molarity, or the final volume?
M1(V1)=M2(V2)
Definition of acid and characteristics
any compound that is able to ionize and form a hydrogen ion (H+ ions) (Ex. HNO3, HC2H3O2,etc)
Characteristics: Sour taste
Definition of monoprotic acid
acid that yields one H+ per molecule of acid
Definition of diprotic acid
acids that yield two H+ per molecule of acid
Definition of bases and characteristics
any substance that is able to accept (react with) H+ ions
Characteristics: Bitter taste, slippery
What does bases produce when dissolved in water?
OH- ions, therefore, bases usually end with OH- (ex. LiOH, NaOH, etc)
Definition of Salt
Any ionic compound whose cation comes from a base and whose anion comes from an acid. (metal and nonmetal)
Definition of neutralization
a reaction where an acid and base are mixed to make a salt and water (harmless)
Definition of electrolyte
Solutes that exist as ions in a solution. Also conducts electricity
Definition of a non-electrolyte
the solutes do not separate into ions. Therefore, don’t conduct electricity
Are non-electrolytes still soluble even if they do not break into ions?
YES
Definition of strong electrolyte
any substance that exists NEARLY all as ions in a solution
most ionic compounds and good conductors
Definition of weak electrolyte
compounds that only PARTLY ionize in a solution. *soluble
*poor conductors
How does a strong acid or base act in water then?
completely ionize in water…good conductor
How does a weak acid or base act in water then?
only partially ionize in water…poor conductor
What are the rules to identify strong and weak electrolytes? (4 rules) (and for rule 2 and 3 what are the exceptions?)
- most salts ARE strong electrolytes
- most acids are weak electrolytes (except: HCl2, H2SO4, HNO3 HBr, HI, AND HClO4)
- Bases made with: Hydroxide (OH-) and either group 1 (alkali) or group 2 (alkaline earth) metals are STRONG…(except NH3)
- Most other substances are non-electrolytes
what is the conversion between grams, volume(or molarity), moles, and particles
Grams —-(use molar mass)—-> moles–(use avagadro’s #)–> Particles OR moles ——(use molarity(M))—> volume (or molarity)
Definition of titration
a method of determining the concentration of an unknown solution
What is needed for a titration?
- standard solution: a solution with a known concentration (M)
- unknown solution: the solution you are trying to determine the concentration of
Definition of equivalence point:
the point at which stoichiometrically equal amounts get together. (creates a neutral solution!)
What indicator did we use in class to get the equivalence point?
phenolphthalein (pink= base and clear = acid)
Definition of end point
when you are close to the equivalence point
Definition of oxidation numbers
in short, oxidation numbers are useful for identifying how many electronss have been taken away from an atom (creating a positive oxidation number) or how many have been gained by an atom (creating a negative oxidation number)
What are the 5 steps to writing net ionic equations
- first write the balanced molecular equation
- then ask yourself (for each molecule): a. is it soluble? (is it aqueous?) b. is it a STRONG electrolyte? (if the answer to either question is no, then it does not completely dissociate!!)
- write the complete ionic equation by separating the ions that have completely dissociated
- cross off the spectator ions in the complete ionic equation
- write the remaining ions and non-aqueous molecules