CH 131

What is solubility, solubility rules, and electrolytes?

Exam 2 Study Guide  

Chapters 4 & 5

Chapter 4

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

How to write atomic structure and lewis structures?

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

What are molecular equations?

If you want to learn more check out How do microbes uptake nutrients?

i. Insolubility rules are based on the chart of insoluble  

compounds

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

A. SOLUTIONS

• Homogeneous mixtures of two or more substances

• The SOLVENT is present in greatest abundance (mostly using WATER) • All other substances are SOLUTES (lesser abundance)

B. ELECTROLYTES 

• 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

C. SOLVATION 

• 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 

• 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.

ACIDS 

• 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  

BASES 

• 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)  

ACID-BASE REACTIONS 

• THE ACID DONATES A H+ ION TO THE BASE  

NEUTRALIZATION REACTIONS 

• When a strong acid reacts with a strong base in an aqueous solution (water)

Chapter 5

a. How to write Atomic Structure and Lewis Structures?