Thinking+about+our+thinking

Lesson 5 Mass/Mole Relationships on the Stochiometry packet was a real challenge for me. It was challenging because it had so much math in it and that day when we went over this lesson i could not focus so it took me a while to learn this. I remember there were three steps to solving a mass/mole relationship problem, although it looked simple on the board step by step i was still confused about how to solve mass/mole relationship problems. I began by looking at the worked example:

Follow the steps above to answer this question. When 50.0g of calcium carbonate is heated it decomposes.

CaCO3->CaO+CO2

a) Calculate the mass of calcium oxide is formed? b) Calculate the mass of carbon dioxide gas formed in the reaction c) What do you notice about the masses of the products and reactants? What is this law called?

So to solve number a i followed the seven steps listed: 1. equation is balanced 2. how many grams of CaO formed 3. 1:1:1 ratio 4. I didn't calculate every single molar mass of each substance because i was lazy and didn't understand how 5. i didn't understand this at all and so for six and seven it was impossible to follow.

I thought i was maybe inactive and needed to actually write down things.This turned out to not work at all. I was going aimlessly. So i decided to write down everything i thought that was important. 50.0g n=m/M m=n*M

Then i figured out what n, m, M meant. n=mol m=mass(g) M=molar mass(gmol-1)

And then i thought about how to solve a...so if i have a 1:1:1 ratio then if i have that much amount then i must produce that much amount in the products. After that i solved the molar mass which was around 100. I looked at the important things i put down and a connection was put with the n=m/M. So i plugged the numbers in

50.0g CaCO3/CaCO3 Molar mass =approximately 0.500mols

And all of a sudden everything made sense after looking at steps 6 and 7 again.

The second equation m=n*M since i already have the mols now all i need to find is M of CaO to find m. And that concludes to approximately 28grams not counting significant figures throughout the process. I thought great now i know how to do it but when i went to the exercises they were actually a lot harder than this question. Now i had the general idea so it would be easier to solve the exercise problems. This sounded like a breeze but it wasn't. At that moment when i didn't get the problem my head was hurting. It actually took me a whole 30 minutes to understand the process. I just sat there and thought because i know that when i ask someone i'll be tempted to look at their process and answer which will not help me at all. I only learn when i think about it over and over and get it right myself.