Chapter 4 Flashcards
what are solutions composed of (2 things)
- solutes
- solvents
solutes
the substances present in smaller amounts, and the component that is dissolved
solvent
the substance present in a larger amount, and the component that is able to dissolve things
solution
a homogenous mixture of 2 or more substances, composed of a solvent and solutes
covalent bond
a bond made between atoms that are sharing their electrons
non-polar covalent bond
the electrons in the atoms are being evenly distributes
polar covalent bond
when the pulling power of one atom is stronger, and the electrons are displaced closer to that atom than the other
why is water a powerful solvent
water is polar, making it a powerful solvent
hydration
the process by which an ion is surrounded by H2O molecules arranged in a specific manner
ionic theory of solutions (Arrhenius)
certain substances (electrolytes and non-electrolytes) produce freely moving ions when they dissolve in water, and these ions conduct an electric current in solution
theoretically, if an electric wire is dipped into a solution of NaCl, how will electricity be conducted
- Na+ ions are attracted to the negative wire
- Cl- ions are attracted to the positive wire
- opposite charges allow an electrical current to flow through
what was the most important idea of Arrhenius’s ionic theory of solutions
- salt and pure water do not conduct electricity BUT
- once salts are dissolved in water, they are conductors
- salt contains ions even in the absence of an electric current
non-electrolyte
a substance that, when dissolved, results in a solution that does not conduct electricity
electrolyte
a substance that, when dissolved in water, results in a solution that can conduct electricity
strong electrolyte
100% dissociation
weak electrolyte
not completely dissociated
non-electrolyte
no cations or anions in the solution
basics of solubility rules
- substances vary in their solubility
- compounds that dissolve readily are said to be soluble
- compounds that dissolve very little are said to be insoluble
soluble
dissolves, aqueous
insoluble
does not dissolve, solid
molecular equation
a chemical equation in which the reactants and products are written as if they were molecular substances, even though they may actually exist in a solution as ions
examples of aqueous solutions that are written as compounds in molecular equations
AgNO3, NaCl, NaNO3
molecular and ionic equations
a chemical equation in which strong electrolytes are written as separate ions in a solution is a complete ionic equation. other reactants and products are written in molecular form
spectator ion
an ion in an ionic equation that does not take part in the reaction. it appears as both a reactant and a product
net ionic equation
an equation in which spectator ions are omitted. it shows the reaction that actually occurs at the ionic level
brief summary of writing net ionic equations (5 steps)
- write balanced molecular equation
- write the complete ionic equation showing the strong electrolytes
- determine precipitate from solubility rules
- cancel the spectator ions on both sides
- write the net ionic form
the 3 main types of chemical reactions
- precipitation
- acid-base reactions
- oxidation-reduction reactions
precipitation reactions
- a solid ionic substance forms from the mixture of 2 solutions of ionic substances
- precipitate (insoluble solid that separates from solution
(Acid) base reactions
- have a sour taste
- react with certain metals to produce hydrogen gas
- redox reactions (react with carbonates an bicarbonates to produce carbon dioxide gas
acid (base) reactions
- have a bitter taste
- feel slippery
- hydroxide (-OH)
arrhenius definition of acids and bases
- an acid is a substance that increases hydrogen ion concentration in water
- a base is a substance that increases hydroxide ion concentration in water
bronsted and lowry definition of acids and bases
- an acid donates a proton
- a base accepts a proton
- an acid must contaon at least 1 ionizable proton
properties of ammonia
a weak base and a 2 arrow-equillibrium sign is used in equations because it doesn’t fully dissociate
strong acid
ionizes completely in H2O (strong electrolyte)
weak acid
partly ionizes in H2O (weak electrolyte)
strong acids and strong bases on periodic table
group 1 and 2 hydroxides
neutralization reaction
- the chemical properties of acids and bases neutralize one another
- a reaction of an acid and a base that results in an ionic compound (a salt) and water
oxidation-reduction reactions
- oxidized=lose e-
- reduction=gain e-
Oxidation number
the charge of an atom or a hypothetical charge assigned to an atom in a molecule (or an ionic compound) using simple rules
free elements
the oxidation number of an atom of an element is zero
monotomic ions
the oxidation number is equal to the charge of the ion
oxidation number of oxygen
is usually -2, in H2O and O2 it is -1
oxidation number of hydrogen
in a compound is +1 except when it is bonded to metals in binary compounds, then it is -1
oxidation numbers of group 1A and 2A metals
1A= +1 2A= +2
oxidation number of flourine
-1
what is the sum of the oxidation numbers in all atoms equal to?
the charge on the molecule/ion
what are the 5 common oxidation-reduction reactions
- combination
- decomposition
- displacement
- combustion
- disproportionation
combination reaction
- 2 substances combine to form a third
- A+B=C
- 2Na + Cl2 = 2NaCl
decomposition reaction
- a single compound reacts to give 2 or more substances
- C=A+B
- 2HgO=2Hg + O
displacement reactions
- element reacts with a compound, displacing another element from it
- A+BC=AC+B
- Sr + 2H2O = Sr(OH2) + H2
combustion reaction
- substances react with oxygen and release heat/flame
- M + O2 = MO2
Disproportionation reaction
- simultaneously oxidized and reduced
- Cl2 + 2OH- = ClO- + Cl- + H2O
how do we describe the concentration of a solution
the concentration of a solution is the amount of solute present in a given quantity of solvent or solution
equation for molarity
molarity = moles of a solute/liter of solution
dilution
the procedure for preparing a less concentrated solution from a more concentrated solition
relationship between volume and molarity
as volume increases, molarity decreases
-MiVi=MfVf
quantitative analysis
involves the determination of the amount of substance or species present in a material
graviametric analysis
a type of quantitative analysis in which the amount of a species in a material is determined by converting it into a product that can be isolated and weighed
what type of reaction is often used in graviametric analysis
precipitation reactions
general procedure of graviametric analysis
- dissolve unknown substance in water
- react the unknown substance with a known substance that is a precipitate
- filter and dry the precipitate
- weigh precipitate
- use the chemical formula and mass of precipitate to determine the amount of unknown ion
volumetric analysis
method for determining the amount of a particular substance based on measuring the volume of a solution of known concentration that is required to achieve a complete reaction
volumetric analysis is based on
titration
titration
procedure for determining the amount of substance A by adding substance B until the reaction of B and A is complete
general procedure for a titration
a solution of accuratley known concentration is added gradually to another solution of unknown concentration until the chemical reaction between the 2 solutions is complete
equivalence point
the point at which the reaction is complete
indicator
substance that changes color at (or near) the equivalence point
