For each reaction in a lab I have to write:
1. the balanced molecular equation including states of matter
2. the balanced complete ionic equation, crossing out spectator ions, including states of matter
3. the balanced net ionic equation, including states of matter
How do you do this?
To write the balanced molecular, complete ionic, and net ionic equations in a lab report, you'll need to follow these steps:
Step 1: Identify the Reactants and Products
First, identify the reactants and products in the chemical reaction. Make a note of their chemical formulas.
Step 2: Write the Balanced Molecular Equation
Write the balanced molecular equation by combining the chemical formulas of the reactants and products. Remember to include the states of matter (s for solid, l for liquid, g for gas, and aq for aqueous solution) next to each chemical species.
Step 3: Write the Balanced Complete Ionic Equation
Convert the reactants and products in the balanced molecular equation into their respective ions. Break apart any aqueous (aq) compounds into their constituent ions. Write the ions in the equation and balance them, including the states of matter for each species.
Step 4: Identify the Spectator Ions
Identify any ions that appear on both sides of the complete ionic equation (spectator ions). These ions do not participate in the reaction and can be crossed out.
Step 5: Write the Balanced Net Ionic Equation
Write the balanced net ionic equation by including only the ions and molecules that participate in the reaction. Exclude the spectator ions identified in step 4. Balance the net ionic equation, including the states of matter for each species.
It's important to note that the molecular equation provides an overall description of the reaction, the complete ionic equation shows all the ions present, and the net ionic equation focuses only on the species involved in the actual reaction.
Let's take an example to illustrate the process:
Example: Reaction between hydrochloric acid (HCl) and sodium hydroxide (NaOH) to form water (H2O) and sodium chloride (NaCl).
Step 1: Identify the Reactants and Products
Reactant: HCl and NaOH
Product: H2O and NaCl
Step 2: Write the Balanced Molecular Equation
HCl(aq) + NaOH(aq) → H2O(l) + NaCl(aq)
Step 3: Write the Balanced Complete Ionic Equation
H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) → H2O(l) + Na+(aq) + Cl-(aq)
Step 4: Identify the Spectator Ions
In this case, Na+(aq) and Cl-(aq) appear on both sides, so they are spectator ions.
Step 5: Write the Balanced Net Ionic Equation
H+(aq) + OH-(aq) → H2O(l)
The net ionic equation shows only the ions directly involved in the reaction, which in this case are H+ and OH- combining to form H2O.
Remember to follow these steps for each reaction in your lab report and include the appropriate states of matter.