HOW TO DETERMINE THE STATE OF A COMPOUND
Here is the SOLUBILITY TABLE that was given during class:
NEGATIVE IONS (ANIONS) | POSITIVE IONS (CATIONS) | SOLUBILITY OF COMPOUNDS (solubility: >0.1mol/L) |
ALL | All Alkali ions | Soluble |
ALL | Hydrogen ion, H+ | Soluble |
ALL | Ammonium ion, NH4+ | Soluble |
Nitrate, NO3¯ | ALL cations | Soluble |
Acetate, CH3COO¯ | ALL cations, except Ag+ | Soluble |
Chloride, Cl¯ Bromide, Br¯ Iodide, I¯ | Ag²+, Pb²+, Hg2²+, Cu+ ALL other cations | Not (low) Soluble Soluble |
Sulfate, SO4²¯ | Ca²+, Sr²+, Ba²+, Ra²+, Ag+, Pb²+ All other cations | Not (low) Soluble Soluble |
Sulfide, S²¯ | Alkali ions, H+, NH4+ Be²+, Mg²+, Ca²+, Sr²+, Ba²+, Ra²+ Any other cations | Soluble Soluble Not (low) Soluble |
Hydroxide, OH¯ | Alkali ions, H+, NH4+, Sr²+ Any other cations | Soluble Not (low) Soluble |
Phosphate, PO4³¯ Carbonate, CO3²¯ Sulfite, SO3²¯ | Alkali ions, H+, NH4+ ALL other cations | Soluble Not (low) Soluble |
Example:
2BeI2( ) + 1Sn(NO3)4( ) → 2Be(NO3)2( ) + 1SnI4( )
Instructions:
- Is 2BeI2( ) a solid or an aqueous substance? First take a look at the Anion, in this case, Iodide. Find Iodide in the left column of the Solubility Table. This is what you should see:
Chloride, Cl¯ Bromide, Br¯ Iodide, I¯ |
- When you have found Iodide in the left column, look at the Cation, in this case, Beryllium. On the Solubility Table, look at the box with Iodide, then look at the box to its immediate right, in the middle column. This is what you should see:
Chloride, Cl¯ Bromide, Br¯ Iodide, I¯ | Ag²+, Pb²+, Hg2²+, Cu+ ALL other cations |
- Look for Beryllium in the middle column. It if is not stated specifically, the it is considered in the “ALL other cations” category.
Chloride, Cl¯ Bromide, Br¯ Iodide, I¯ | Ag²+, Pb²+, Hg2²+, Cu+ ALL other cations |
- Now look to the immediate right of the middle box. This is what you should see:
Chloride, Cl¯ Bromide, Br¯ Iodide, I¯ | Ag²+, Pb²+, Hg2²+, Cu+ ALL other cations | Not (low) Soluble Soluble |
Look at the one that is directly to the left of the highlighted part, not the other one. It should be like this:
Chloride, Cl¯ Bromide, Br¯ Iodide, I¯ | Ag²+, Pb²+, Hg2²+, Cu+ ALL other cations → | Not (low) Soluble Soluble |
When it is SOLUBLE, it means it is an AQUEOUS. When it is NOT (low) SOLUBLE, it means it is a SOLID.
Therefore, 2BeI2( aq )
When you do the whole equation, it should look like this:
2BeI2( aq ) + 1Sn(NO3)4( aq ) → 2Be(NO3)2( aq ) + 1SnI4( s )
DOUBLE REPLACEMENT
- The reaction between 2 ionic compounds
- The positive ions switch places with one another
General formula:
AB + CD → CB + AD
For example:
When a solution of silver nitrate is combined with a solution of sodium chloride, silver chloride and Sodium Nitrate are formed.
AgNO3 + NaCl → AgCl + NaNO3
BUT, how can we determine whether or not a reaction actually occurs?
- Look back at the Solubility Table mentioned earlier.
- There is a reaction if the reactants change states during reaction.
- The change usually forms a precipitate (aqueous).
- There is no reaction if there is no change in states.
When you’ve figured out the states, it should look like this:
AgNO3( aq ) + NaCl( aq ) → AgCl( s ) + NaNO3( aq )
The reaction changed states, therefore, this reaction can occur.
NEUTRALIZATION
- A special type of Double Replacement
- Happens when an ACID and a BASE reacts to produce WATER and an ionic SALT
- The formula for an ACID always contain H+ as the cation
- The formula for a BASE always contain OH¯ as the anion
- An exception to this is H2O, aka. HOH, because it is neutral.
General formula:
HA + BOH → H2O + BA
For example:
Hydrochloric acid combined with Sodium Hydroxide is neutralized to form Sodium Chloride (salt) and water.
HCl + NaOH → NaCl + H2O
COMBUSTION
- a COMBUSTION reaction happens when a compound is burned with oxygen
General formula:
AB + O2 → AO + BO
For example:
When methane burns with oxygen, it produces carbon dioxide and water.
1CH4 + 2O2 → 1CO2 + 2H2O *don’t forget to balance!!
How to Calculate the Net Ionic Equation
~JZ
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