11/22

review yesterday: When reaction occurs, the pressure changes to create equilibrium with the atmosphere.


Regular buildings don't affect atmospheric pressure.

We talked about laws of gases and changes in pressure that are regulated in certain buildings or underground caves and how pressure differences can be used to contain viruses in the CDC building.

Stoichiometry:

Volume of a gas under 2 sets of conditions, non-standard temperature and non standard pressure

Here are some examples, these problems can be found in the Unit 5 handouts folder, here’s how to set up the equations if you don’t understand it.

Ammonia is NH3, our “B” chemical, 6NO is our “A” chemical, however there is a typo in the question, there is no indication of pressure or temperature, so we assume STP and -273 degrees kelvin.

Start by writing 12 L NO, turn it into moles by using volume, 1 mol NO/ 22.4L NO.

12 L NO x(1 mol NO/22.4 L NO) x (4 mol NH3/6 mol NO) x (22.4 L NH3/1 mol NH3)

12 x 4 / 6 = 8 L NH3

102 g H2S x (1 mol/34.09 g H2S) x (3 mol O2/2 mol H2S) x (22.4 L O2/1 mol O2) =

100.5 ->101 L O2

12 g H2O2 x (1 mol H2O2 / 34.02 g H2O2) x (1 Mol O2 / 2mol H2O2) = 0.18 mol O2 -> PV=nRT

746 mmHg x V = 0.10 mol O2 x 62.4 (Lx mmHg/mol x K) x 300 K

V= 4.5 L

REMEMBER: You can treat volume like moles when its at standard pressure.

At the end of class today we did a demo about pressure how marshmallow and shaving cream expand in in volume when pressure is decreased and shrivel when pressure increases.

DONT FORGET TO DO YOUR PACKET THIS WEEKEND AND STUDY