#### Reactive Material Balance: Screencasts

We suggest that after watching each screencast, you list the important points as a way to increase retention.
###### Screencast 1:

Reviews stoichiometry, balancing reactions, and limiting reactants.

###### Screencast 2:
An overview of how to use the extent of reaction in a material balance involving multiple reactions.
###### Screencast 3:

Performs a molecular species balance for a single reactor.

##### Important Equations:

$\xi = \frac{n_i – n_{i,in}}{v_i}$

where $$n_i$$ is the number of moles leaving the system (or the number of moles at a given time in a closed system),

$$\xi$$ is the extent of reaction dimensionless, and

$$v_i$$ is the stoichiometric coefficient (mol) (positive for products, negative for reactants).

Note that many textbooks use the notation where $$v_i$$ is dimensionless and ξ has units of moles.

$f = \frac{n_{i,in} – n_i}{n_{i,in}}$

where $$f$$  is fractional conversion.

Balance on atomic species: input = output

Balance on reactants: input = output + consumption

Balance on products: input +generation = output

degrees of freedom (molecular species balance) = # unknowns +# independent reactions – #independent molecular species balances – # equations relating unknown variables

degrees of freedom (atomic species balance) = # unknowns +# independent atomic species – #independent molecular species balances for nonreactive species – # equations relating unknown variables.