How to Understand Stoichometry
What is Stoichometry?
Let's Start with the Basics
It's a Double Replacement type of reaction. Remember to switch metal with metal OR non-metal with non-metal.
Keep the equation balanced on both sides, don't forget the charges and include the states of matter! (States of matter should be either aq, s, or l)
Balanced Equation (with states of matter):
Fe (SO4) aq + Ba (NO3)2 aq -----> Fe (NO3)2 aq + Ba (SO)4 s
Get to Know the Elements
Time for CONVERSIONS!
Let's Talk about Conversions and How To Do It
Okay, so conversions with two different elements... It seems difficult but it's not. Keep in mind what you are solving for, the units, and of course the mole ratio.
Now how to do it, well you've already learned how to do mole to mole conversion which is simple enough. Given an amount of moles from the question, you use the coefficients of your balanced equation and place it in the right spot. Multiply across the top and divide by the bottom. If you don't remember there'll be a visual example below. So that's mole to mole but then there's mass to mass conversion. This process is much longer but it's actually simple. Explaining it in words will just confuse everyone so look at the picture!
Limiting and Excess Reactants
Here is what I call the set up. Remember what goes where and finding limiting and excess reactants will be easy as pie!
Okay, now there is where you actually have to do stuff. Look at the set up and fill in accordingly. Keep in mind, you're setting up this conversion TWICE. One for excess and one for limiting. You won't know which one is which until the end.
Once you fill in everything, if you did it correctly, all the units should cancel each other out and only leave what you are trying to find left.
Multiple across the top and divide by the bottom like you've been doing. Once you get both numbers, determine which one is the excess and limiting factor. Keep in mind that it is not the answer you get at the very end but rather one of the REACTANTS that will be the limiting and excess. CONGRATULATIONS! You have lived through limiting and excess reactants calculations.
Theoretical and Percent Yield
Barium Nitrate is being added to the test tube
The mixture immediately becomes a white, cloudy liquid. A precipitate has formed
After 2 minutes, the precipitate and liquid begin to separate.
After 4 minutes most of the precipitate has settled in the bottom of the test tube
After 6 minutes, the mixture has completely separated and the solid has settled on the bottom. The liquid is still a murky, white color