1)To prevent the presence of air, noble gases are placed over highly reactive ch

Question

1)To prevent the presence of air, noble gases are placed over highly reactive chemicals to act as inert "blanketing" gases. A chemical engineer places a mixture of noble gases consisting of 4.66 g of He, 15.8 g of Ne, and 36.6 g of Kr in a piston-cylinder assembly at STP. Calculate the partial pressure of each gas.
PHe =     atm
PNe =   atm
PKr =    atm

2) When 36.6 L ammonia and 38.5 L oxygen gas at STP burn, nitrogen monoxide and water are produced. After the products return to STP, how many grams of nitrogen monoxide are present?
- g

Explanation / Answer

2. 4 NH3 + 5 O2 ---> 4 NO + 6 H2O

Since 1 mole of any gas at STP is 22.4 liters, you can calculate moles of NH3 as:

36.6L/22.4l/mole = 1.63mole

Because the volume of O2 is specified (not excess), we need to see which reagent is the limiting reagent:

Moles of O2 are:

38.5LO2/22.4 liters/mole = 1.71 moles O2

Because we need 5 O2's for each 4 NH3, to react all the NH3 we would need:

1.63 mol NH3 x (5moles O2/4moles NH3) = 2.03 moles O2

We only have 1.71 moles O2, so not all the NH3 will react; we will only produce;

1.71 x (4 mole NO/5moleO2) = 1.36 moles of NO

Now multiply moles by molecular weight of NO to get grams:

1.36 moles NO x (16.0 + 14.01) = 40.8 g NO

Related Questions

Navigate

• Browse (All)
• Browse 1
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.