Chapter 4: Types of Chemical Reactions and Solution Stoichiometry Flashcards
Polar molecule
Contains an unequal
distribution of charge
define
Hydration
- Process by which the positive side of H2O molecules is attracted to negative ions. And the negative side of water molecules is attracted to positive ions
- Causes salt to split when dissolved in water (When ionic salts dissolve in water, they break into individual cations and anions)
What does the solubility of ionic substances in water varies depending on
- The attraction between ions of opposite charges
- The attraction of ions for water molecules
Which substances are expected to be more soluble in water
Polar and ionic substances OR nonpolar
Polar and ionic substances
Solute vs. solvant
- Solute : Substance being dissolved
- Solvent : The dissolving medium
define
Electrolyte
Substance that dissolves in water to produce a solution that can conduct electricity
Strong electrolytes are…
Highly efficient conductors of current in aqueous solutions
fully ionize in water
Weak electrolytes…
Conduct small current in aqueous solutions
Nonelectrolytes
Do not conduct current in aqueous solutions
What does the extent to which solutions can conduct electricity depend on
It depends on the number of ions present
Types of strong electrolytes
- soluble salts
- strong acids
- strong bases
when disolved in water, how do acids act
and what do they produce
They act as strong electrolytes
(produce H+ ions)
What am I?
Every molecule is completely ionized when dissolved in water
A strong acid
Ionization of an acid
x + x –> x + x
HA(aq) + H20(l) –> H3O+(aq) + A-(aq)
How does a strong base act
- what it produces and what it contains
- Contains the OH- ion
- when dissolved in water, cations of OH- ions seperate and move independently
Dissolving KOH in water
x –> x + x
KOH(s) –> K+(aq) + OH-(aq)
Weak electrolytes…
- Exhibit a small degree of ionization in water
- Include weak acids and weak bases
*dissociate only to a slight extent
What will be the resulting solution of a weak base
a weak electrolyte
What is a nonelectrolyte
Substances that dissolve in water but do not produce any ions (leads to absence of electrical conductivity)
What is molarity
Moles of solute per volume of solution in liters
What is dilution
Process of adding water to a concentrated (stock) solution to achieve the molarity desired for a particular solution
Why is this correct:
Moles of solute after dilution = moles of solute before dilution
Since only water is added to accomplish dilution
Formula for dilution
M1V1=M2V2
- M1 + V1 = for original solution
-M2 + V2 = for diluted solution
Steps for the preperation of a standard aqueous solution
Process of preparation:
1. Place a weighed amount of the solute into a volumetric flask, and add a small amount of water
2. Dissolve the solid by swirling the flask
3. Add more water until the level of the solution reaches the mark etched on the flask
4. Mix the solution by inverting the flask several times
Precipitation Reaction
When two solutions are mixed, a precipitate separates from the solution
What is precipitate
Insoluble solid that is formed in a precipitation reaction
What kind of reaction is this:
When a yellow aqueous solution of potassium chromate is added to a colourless aqueous solution of barium nitrate, yellow barium chromate precipitates
A precipitation reaction
Rules of solubility of salts in water
(6)
- Most nitrate (NO3-) salts are soluble.
- Most salts containing the alkali metal ions (Lit, Na+, K+, Cs+, Rb+) and the ammonium ion
(NH+) are soluble. - Most chloride, bromide, and iodide salts are soluble. Notable exceptions are salts containing the ions Ag+, Pb2+, and Hg2 2+,
- Most sulfate salts are soluble. Notable exceptions are BaSO4, PbSO4, Hg2SO4, and CaSO4.
- Most hydroxides are only slightly soluble. The important soluble hydroxides are NaOH and
KOH. The compounds Ba(OH)2, Sr(OH)2, and Ca(OH), are marginally soluble. - Most sulfide (S2-), carbonate (CO3 2-), chromate (CrO4 2-), and phosphate (PO4 3-) salts are only slightly soluble, except for those containing the cations in Rule 2.
What am I?
- shows the complete chemical formula of reactantsand products
- Does not provide correct information regarding the actual forms of the
reactants and products
Formula equation
What am I?
All reactants and products that are strong electrolytes are presented as ions
Complete ionic equation
What am I?
Includes the solution components that undergo change (does not include spectator ions)
Net ionic equation
What are spectator ions
Ions that do not participate in a chemical reaction
According to the Brønsted Lowry definitions for acids and bases:
What is an acid and what is a base
- Acid: it’s a proton donor
- Base: It’s a proton acceptor
What is a neutralization reaction
The name given to acid base reactions
-An acid is neutralized when enough base reacts exactly with it in a solution
What is volumetric analysis
Technique used to ascertain the concentration of a given solution by using a solution of known concentration
What is titration, a titrant and an analyte
-Titration: Delivery of a titrant into an analyte
- Titrant: Solution of known concentration
- Analyte: It’s the solution being analyzed
In an acid-base titration
What is the equivalence (stoichiometric) point
Marks the point in titration where enough titrant has been added to react exactly with the analyte
Definition of indicator
Substance added to show the end point of titration
(Changes color at the equivalence point)
What is the endpoint
Point where the indicator actually changes color
Requirements for a successful titration
(3)
- Exact reaction between titrant and analyte must be known and must be rapid
- Equivalence point must be accurately marked
- Volume of titrant that is needed to reach the equivalence point must be accurately known
what is Phenolphthalein
An indicator used in acid-base titrations
- Colourless in an acidic solution
- Pink in a basic solution
What is an oxidation-reduction (redox) reaction
Involve the transfer of one or more electrons
What is an oxidation state
For atoms in covalent compounds
imaginary charges that atoms would have if:
- Shared electrons were equally divided between identical atoms bonded to each other
- The shared electrons are assigned to the atom with the greater electron affinity
What is an oxidation state
For monoatomic ions
the oxidation state is the charge of the ion
What must the sum of oxidation states equal for electrically neutral compounds?
zero
Oxidation
What is it? what is it characterized by?
- Increase in oxidation state
- Characterized by a loss of electron
Reduction
What is it? what is it characterized by?
- Decrease in oxidation state
- Characterized by a gain of electron
Reducing agent
Electron donor
Oxidizing agent
Electron acceptor
