MOLAR VOLUME!!!

Today we learned about Moles to Volume conversions.... ooooo sounds complicated? Well it's actually not too shabby! (Does anyone use that word anymore?)

 Before we start please note:
At a specific pressure and temperature one mole of any gas occupies the same volume!
Note: *at 0 degrees Celsius and 101.3 kilo Pascals, 1 mole : 22.4 Litres
This temperature and pressure is called STP which stands for Standard Temperature Pressure.


22.4 L/mol is the molar volume at STP


Lets try some examples shall we.....


How many liters will 2.5 mol of H2 occupy at STP?


Start with what you're given... which is 2.5 mol
You want to find how many liters are in 2.5 mol of H2!
Your equation will look like this:


2.5 mol x 22.4 L/ 1 mol = 56 L


Lets try some more! Isn't this fun


-----> A certain gas is found to occupy 11.6 L at STP. How many moles?


11.6 L x 1 mol / 22.4 L = .518 mol


------> At STP an unknown gas is found to occupy 150mL. How many moles of gas must there be?
First off, we see that the volume is measured in mL. We must change it to liters!


First step: 150mL x 1 L / 1000 mL = 0.150 L
Second step: 0.150 L x 1 mol/ 22.4 L = 0.00670 mol
Remember significant digits! In this case, we round to 3 sig figs! 


Getting there? GOOD! :)


alright so let's try one more example and lets see if you get the gist of it all!


A certain amount of Chlorine gas occupies 1.6 L. Find the # of moles present and then determine the mass of chlorine.


So in this specific equation, we are asked to find 2 things. The number of moles present and the mass of chlorine. We shall start off with what we're given!


1.6 L x 1 mol / 22.4 L = 0.71 mol


You figured out the number of moles! Now find the mass of chlorine!


0.71 mol x 71 g/ 1 mol = 5.1 g
Dont forget Chlorine is diatomic so the equation on the top would be 2(35.5) which gave us the number 71!


And das it! Good job everyone! 

Post by Ren Ren