Help me please I need help

When balancing a chemical equation:

Astudent reacts 13 moles of iron with 21 moles of oxygen according to the following equation:

Calculate the ph at the equivalence point for the titration of a solution containing 150.0 mg of ethylamine (c2h5nh2) with 0.1000 m hcl solution. the volume of the solution at the equivalence point is 250.0 ml. kb forethylamine is 4.7 × 10−4 .