🤓 Based on our data, we think this question is relevant for Professor Tang's class at USF.

A mixture of NH_{3}(g) and N_{2}H_{4}(g) is placed in a sealed container at 320 K . The total pressure is 0.49 atm . The container is heated to 1200 K at which time both substances decompose completely according to the equations 2 NH_{3}(g) → N_{2}(g) + 3 H_{2}(g); N_{2}H_{4}(g) → N_{2}(g) + 2 H_{2}(g). After decomposition is complete the total pressure at 1200 K is found to be 4.5 atm.

Find the percent (by volume) of N_{2}H_{4}(g) in the original mixture. (Assume two significant figures for the temperature.)

First, we **set variables** for the moles of each reactant:

We can** add them up to get the total initial moles reactant. **

Next, we **use these variables to express the amount of product** by doing a **mole to mole comparison** using the coefficients of the balanced reaction. The mole products are just the sum of its coefficient per reaction.