Exam 2 Study Guide
Chapters 4 & 5
1. What is Solubility, Solubility Rules, and Electrolytes?
a. Demonstrating Conductivity
1) Not conductive = no light in the lightbulb
2) Slightly conductive = slight dim light
3) Highly conductive = bright lightbulb
b. Molecular Compounds in Aqueous Solutions
1) When molecules dissolve in water, they disperse throughout the solution 2) An ACID when dissolved in water, dissociates into protons (H+ molecules) 3) Neat acids exist as molecules but dissociate like ions in aqueous solutions 4) Neat = pure (no water in it)
c. Strong vs. Weak Electrolytes
1) Strong electrolytes exist completely as ions in aqueous solutions (ACIDS) 2) Soluble ionic compounds (NaCl)
3) Weak electrolytes do not dissociate completely (CH3COOH) (acetic acid) 4) Weak acids are also weak electrolytes (MAKE SURE TO MEMORIZE STRONG ACIDS) Don't forget about the age old question of What is stated by the law of supply?
d. Weak vs. Strong vs. Soluble
1) Solubility refers to the ability of the compound to DISSOLVE IN WATER 2) Insoluble reactions form a PRECIPITATE
If you want to learn more check out How do microbes uptake nutrients?
i. Insolubility rules are based on the chart of insoluble
e. Solubility Rule
1) If more than 0.1 moles of a substance dissolves in water, it is called soluble. 2) If less than 0.1 moles of a substance does not dissolve, it is insoluble. i. ALL THE IONIC COMPOUNDS OF GROUP 1A (excluding
Hydrogen) ARE SOLUBLE
ii. ANY COMPOUND WITH (NH4+) (ammonium ion) WILL
ALWAYS BE SOLUBLE
• Homogeneous mixtures of two or more substances
• The SOLVENT is present in greatest abundance (mostly using WATER) • All other substances are SOLUTES (lesser abundance)
• Substances that dissociate into ions when dissolved in water (COMPLETELY BREAKS DOWN/CONDUCTS ELECTRICITY)
• A NONELECTROLYTE may dissolve in water, but it does not dissociate into ions when it does so (STAYS NEUTRAL)
• Strong electrolyte: DISSOCIATES COMPLETELY IN WATER (100% FULL IONIZATION)
• Weak electrolyte: ONLY DISSOCIATES PARTIALLY
• When an ionic substance dissolves in water, the water pulls the individual ions from the crystal and hydrates them
• THIS PROCESS IS CALLED SOLVATION If you want to learn more check out What does normative theory mean?
We also discuss several other topics like The first step in strategic planning involves what?
• The ions are dissociated when the substance dissolves (COMPLETELY BREAKS DOWN/IS COMPLETELY HYDRATED)
D. PRECIPITATION REACTIONS
• Precipitation reactions are reactions that result in the formation of an insoluble product
• A precipitate is an insoluble solid formed by a reaction in solution • When one mixes ions that form compounds that are insoluble (as could be predicted by the solubility guidelines), a precipitate is formed
E. SOLUBILITY RULES
• Solubility is the amount of a substance that can dissolve in a given quantity of solvent
• STUDY THE CHART IN THE CHAPTER 4 POWERPOINT
EVER SEE NO3 OR C2H3O2 THEY ARE ALWAYS SOLUBLE
A MAJORITY OF CLORIDE IS SOLUBLE (AG AND PB AND HG) LEARN SULFATE (SO4) HAS (SR, BA, HG, AND PB) Don't forget about the age old question of Where was the tango born?
ANY ALKALI METAL CATIONS ARE SOLUBLE (LEARN THE ALKALI METAL CATIONS)
NH4 WILL ALWAYYYYS BE SOLUBLE
F. METATHESIS (EXCHANGE) REACTIONS
• Metathesis comes from a Greek word meaning "to transpose"
• It appears the ions in the reactants switch around in the product • First with last and first in the second with last in the first
• Molecular equations shows the complete chemical formula of the reactants and products WITHOUT INDICATING ANY CHARGES ON THE SPECIES
COMPLETE IONIC EQUATIONS
• All strong electrolytes (strong acids, strong bases, and soluble ionic salts) are BROKEN DOWN INTO THEIR IONS
• This more accurately reflects the species that are found in the reaction mixture
• ANY WEAK ELEC, NONELEC, OR INSOLBLE COMPOUND STAYS IN ITS NONCHARGED FORM
NET IONIC EQUATIONS
• CROSS OUT ANYTHING THAT DOES NOT CHANGE FROM REACTANT TO PRODUCT (LEFT TO RIGHT)
• Those that are deleted are called SPECTATOR IONS
• KEEP THE CHARGES IN THE NET EQUATION
G. WRITING NET IONIC EQUATIONS
1. Write a balanced molecular equation
2. Dissociate all STRONG ELECTROLYTES
3. CROSS OUT UNCHANGED
4. Write the net ionic equation with the species that remain (WERE CHANGED) We also discuss several other topics like Define biological evolution and some mechanisms that drive it.
• Substances that ionize in aqueous solution to FORM HYDROGEN IONS H+1 • Acids are often called PROTON DONORS
• Monoprotic, diprotic, etc. (DEPENDING ON HOW MANY HYDROGENS THERE ARE)
• ACIDS CAN BE SPOTTED BY THE HYDROGEN WRITTEN FIRST
• Substances that accept (react with) H+ ions
• BASES PRODUCE OH- IONS IN WATER
• Proton acceptors
• Strong bases (completely ionized are the soluble salts of hydroxide ions • ALKALI METALS, CALCIUM, STRONTIUM, BARIUM
• Many bases do not contain OH- ions directly (THESE ARE WEAK BASES) ( Ammonia (NH3) − weak base)
• THE ACID DONATES A H+ ION TO THE BASE
• When a strong acid reacts with a strong base in an aqueous solution (water)
a. How to write Atomic Structure and Lewis Structures?