Which are You?
Day 22:
Somehow we have made it this far. We believe it due to the gas law keeping us going every day now. The ideal gas law is saving our lives. The equation PV=nRT can be algebraically used to create the other equations the can be seen in Matt’s post. PV=nRT can be used to find many numbers and calculations. When it comes to such things, there are two kinds of people: walking into fire or knowing what is going on. Either way, it is a much needed thing in life. This simple breakdown of the math will give even the most stressful situations better...we hope. These equations can be used to find the amount of gas in balloons or in an oxygen tank. This could make a birthday party easier or save a life in the back of an ambulance.
So let’s see it!
First let’s break down the equation:
P=pressure in atmosphere (atm)
V=volume in Liters (L)
n= number of moles (mol) Moles are a unit of measurement regarding molecules in an equation.
T=Temperature in Kelvin (K)
R=0.08206 L*atm / mol*K (This number never changes)
Word problems give us the information you can use to substitute the letters for numbers.
How many moles of oxygen will occupy a volume of 2500 mL at 1.20 atm and 25 °C?
So we know what we have and what we need:
P= 1.20 atm
V= we have to change ml to L. To do this, we move the decimal point left three spots to get 2.5 L.
n= This is what we are looking for in mol
T= We now have to change Celsius to Kelvin. We do this by adding 273°C to our current temperature so we get 298 K.
R=0.08206 L*atm / mol*K
(1.20atm)(2.5L)= (n)(298K)(0.08206 L*atm/mol*K)
3.00atm*L =24.45388 L*atm/mol
---------------------------
24.45388 L*atm/mol
The L and atm cancel out leaving 0.1226 mol. We have to round to have 2 digits because we have to match the smallest amount of digits we used in the equation. Due to the volume only having two digits we have to round 0.1226 to 0.12 mol. This is how many mols we have when we have a volume of 2500 mL at 1.20 atm and 25 °C.
So congratulations, we made it through the math using the ideal gas law!