Conventions for writing equations

What are the conventions for writing equations?

1. Reactants on the left and products on the right, separated by an arrow
2. Physical states are denoted by subscripts following the atom or molecule: ($s$) for solids, ($l$) for liquids, ($g$) for gases, and ($aq$) for aqueous solutions, i.e. substances dissolved in water.
3. Coefficients are used to balance equations: if none is present, it is assumed to be equal to one. $_{Subscripts}$ after an atom denote the number of atoms within a molecule while $^{superscripts}$ after a molecule or atom denote charge.

How do you balance equations?

Practice. There is no straightforward way to go through it. I suggest looking at the least-represented atom on either side and starting from there. Red-ox equations require certain steps - refer to the Red-ox chapter on page for an in depth review.

What are limiting reactants and how do you identify them?

The reactant that is completely consumed in a reaction. Or, the reactant, by its limited quantity and inevitable consumption in a reaction, that prevents a reaction from proceeding.

To identify a limiting reactant begin with balancing the equation and convert any given masses to moles. Then, identify how many moles of the reactants are needed for the balanced reaction to proceed. Finally, compare the moles of all the reactants with each other and identify the least represented reactant.

What are theoretical yields and how do you calculate them?

A method for researchers to predict what is the best outcome of a given experiment. The theoretical yield is very difficult to obtain experimentally and responsible for TAs docking points off of your grade and drives industries to find innumerable ways to maximize profits.

To calculate a theoretical yield, identify the amount of reactants and calculate the limiting reactant. With the limiting reactant, you can calculate the maximum amount of achievable product. Finally, divide your experimental yield by the theoretical yield and you will see how good you did.