Unit 4 - Chemical Reactions Flashcards
Physical Processes
Involve changes in intermolecular interactions
Properties change but composition remains the same
Physical Processes examples
Phase changes
Formation/separation of mixtures
Chemical Processes
Involve the breaking and/or formation of chemical bonds
Gray Area b/t physical & chemical processes
Dissolving a salt in water involves breaking ionic bonds and creating ion-dipole interactions
Phase change
Changes in intermolecular interactions result in changes in properties but the composition remains the same
Phase change examples
NO(s) -> NO(l)
Making a solution
Changes in intermolecular interactions result in changes in properties but the composition remains the same
Making a solution examples
NH3(l) -> NH3(aq)
Chemical Processes
Involve the breaking and/or formation of chemical bonds
Substances are transformed into new substances that may have different properties
Chemical processes may be indicated by…
Temperature changes Production of light Formation of a gas Formation of a precipitate Changes in color
Chemical process b/t Sodium & Chlorine may be represented by what equation?
2Na(s) + Cl2(g) -> 2NaCl(s)
What is the gray area b/t chemical & physical processes?
Dissolving a salt in water involves breaking ionic bonds and creating ion-dipole interactions
Gray area example of dissolving of table salt
NaCl(s) -> Na+(aq) + Cl-(aq)
In chemical reactions, the mass and atoms are
Conserved
Mass of reactants = Mass of products
Procedure for Balancing Chemical Equations
1- Write chemical formulas for all reactants & products
2- Balance elements that do not exist independently first by adding coefficients
3- Balance elements that exist independently last
4- Check to make sure that both sides are balanced
Net Ionic Equation
Only shows the reaction that actually took place
Complete Ionic Equation
Shows all of the ions present & precipitate
Molecular Equation
Shows the solutions that were mixed & precipitate
Ba2+(aq) + SO42-(aq) -> BaSO4(s) is considered a
net ionic equation
Ba(NO3)2(aq) + Na2SO4(aq) -> 2NaNO3(aq) + BaSO4(s) is considered a
molecular equation
Ba2+ + 2NO3- + 2Na+ +SO42- -> 2Na+ + 2NO3- + BaSO4(s) is considered a
complete ionic equation
Limiting reactant
Reactant that is used up limits how far the reactio will proceed
Excess Reactant
Reactant that is leftover when the reaction is complete
Precipitation Reactions
Attractive forces between oppositely charged ions is greater than the forces of attraction between water molecules and ions
All salts containing which ions are soluble in water?
Na+
K+
NH4+
NO3-
Oxidation Reduction Reactions
Election transfer reactions
When a substance is oxidized, it
Loses electrons
When a substance is reduced, it
Gains electrons
LEO the lion says GER
loses electrons - oxidized
gains electrons - reduced
Single Replacement REDOX rxn b/t iron and copper(II) sulfate
Fe(s) + Cu2+(aq) -> Fe2+(aq) + Cu(s)
How can you tell what gets oxidized and what get reduced?
Answer is in the oxidation numbers
For an atom in its elemental form, its oxidation number is
zero
OD of Mg, H2, O3
ZERO
For a monatomic ion, its OD is equal to its
Charge
OD of Mg2+
+2
OD of Cl-
-1
OD for oxygen in a molecular compound is
-2
