General Chemistry 1: Stoichiometry

N$_2$ + 3 H$_2$ $\longrightarrow$ 2 NH$_3$

How many grams of hydrogen are needed to produce 68 g of ammonia? (molar mass of NH$_3$ = 12.031 g/mol, the molar mass of H$_2$ = 2.015 g/mol)

2 Al + Fe$_2$O$_3$ $\longrightarrow$ Al$_2$O$_3$ + 2 Fe

An operation requires at least 86.0 g of Fe to be produced. What is the minimum mass in grams of Fe$_2$O$_3$ necessary to produce the desired amount of products? How much Al$_2$O$_3$ is produced as a side product?

MM of Fe$_2$O$_3$ = 159.489 g/mol

MM of Al$_2$O$_3$ = 101.961 g/mol