When we took that quiz on Nov. 23 I was stressing out. I had a quiz in chem 1st hour, midterm 2nd hour and test in trig 4th hour. I did ALL of the extra practice in packets that are in schoology. After all of that I felt confident about the quiz. All of my hard work was put to use because I got a great grade on the quiz!!! Now if only I can do that on my test!! I feel like the first sections we talked about are pretty basic and it's honestly not too bad! It's just basically switching cations with the other anion! Plus adding the solubility rules which are pretty easy to remember. You just use those rules to see if a solid was produced from the reaction (switching cations with anions). An example of a solid is AgCl. An example of a non solid is CaCl.
Above is an example of a Double Replacement reaction. I thought these were confusing at first but after a TONS of practice I got a handle on it! We did a lab on it! We had to take 2 solutions and mix them together. If they didn't turn a color then no solid was produced. To me the lab was super fun! There were some reactions though that didn't follow the solubility rules. But I would say for the most part the solutions followed the rules!
So at first I was very confused about the rules. I had to look at the piece of paper to remember the rules! In all honesty I thought I wouldn't be able to remember everything with all the exceptions and stuff! But I found it helpful to color the periodic table in 2 colors. One color representing the soluble elements and one representing the insoluble elements. It helped me visualize it much better. Then I made flashcards of the rules which helped me a lot too! I also found a video with acronyms to help as well! Check it out below!
My foods teacher in 7th hour always says that cooking is a science. When you think about it, it's actually true! When you're baking cookies, you need precise measurements of a substance otherwise the taste of the food will turn out terrible and disgusting. In science you need precise measurements for your experiments otherwise things could explode if you have too much or too little of something. In cooking, you have these measurements that are mixed together in a mixture. Then you will cook/bake the mixture. This allows the substances in the mixture to bind their chemical composition together. In chemistry, you use heat to bind the mixture's chemical composition. Cooking and chemistry have many similarities than anyone would think of!
So today we did the Formula of a Chloride Lab. The prelab was a breeze and thankfully my lab partner got the answer too so we could do the lab. All in all, I thought this lab was fun! However when we were heating the liquid away (hydrochloric acid), it gave me a nasty headache. Not to mention 98% of the class was also doing the lab so the aroma of the acid was VERY strong! When we finished the lab and went to the bathroom to wash our hands, I felt such a relief to have clean air. I really didn't want to go back to the classroom. I wasn't even putting my nose over the compound to smell it, for it was just sitting in the air. I learned a lot in that lab and got some personal experience on how Zinc and hydrochloric acid react with each other. It was kinda funny to see the Zinc dancing around on the bottom of the beaker because of how hot it was.
I know these are a lot of links all at once but hopefully this will appeal to different types of people in how they perceive things! I love all of these links and I think it will help! Extra practice helps!!!
I thought I did really good on it with two questions I wasn't sure about. However I guess I messed up on my calculations and I didn't get a good grade. I think the problem I have the most with problems is how to start them, Once I figure that out then it's easy from there. Also another thing I have trouble with is trying to understand what the problem is saying. Sometimes the problem to me is just too wordy and it gets all confusing to me. I studied a LOT for that quiz. I was up all night looking at my notes, solving different types of problems, looking through the study guides in the packet, etc. Hopefully I will do better on the next quiz or test. But at least I will learn from my mistakes so on the next quiz or test I'll know exactly what not to do and what I should do on these types of problems! :) But what I found helpful is to circle the given information and circle again what it is trying to ask. This helped when I went back through my quiz to do corrections!
Many of us are confused on how to solve these type of questions and frankly I was too! It takes a little brain power and practice to solve it!
Suppose a student does an experiment to determine the formula of the hydrate: Cr(NO3)3 x nH2O
Mass of Test Tube: 16.114g
Mass of Test Tube + Cr(NO3)3 x nH2O: 34.909g
Mass of Test Tube + Cr(NO3)3 x nH2O (1st heating): 27.335g
Mass of Test Tube + Cr(NO3)3 x nH2O (2nd heating): 27.335g
Find n.
Now where the heck to we start?!?!
First of all what is the hydrated compound? Well it's the compound with the water added to it!! Hence hydrated. It's Cr(NO3)3 x nH2O.
Second of all what is the anhydrated compound? It's the compound without the water. Hence ANhydrated. It's Cr(NO3)3. It's also known as the salt.
So we have a test tube that weighs 16.114g. Is this mass part of the compound? NO!! So we must subtract it from any compound to get the mass of what is inside of it!
That will give us 39.909g - 16.114g = 18.795 g of the hydrated compound
Then we want to figure out the mass of the anhydrated compound (without the water).
So we must take the last mass of the last heating which is 27.335g. But WAIT!!!!! You have to remember to subtract the mass of the test tube which is 16.114g.
That will give us 27.335-16.114g = 11.221g of the anhydrated compound.
So we know the mass of the hydrated compound (with water) and the mass of the anhydrated compound (without water), so next we need to figure out what mass of water was driven off/evaporated. That means we need to subtract the hydrated mass from the anhydrated to give us the mass of the water.
That will give us 18.795g - 11.221g = 7.574g of H2O
Now we need to convert the H2O and anhydrated into moles.
7.574g H2O x (1mol / 18.02 molar mass) = 0.4203 g (KEEP IN MIND OF SIG FIGS!!!!!)
11.221 g Cr(NO3)3x (1mol / 238.03 molar mass) = 0.047141 g(KEEP IN MIND OF SIG FIGS!!!!!)
A little trick to know is that is the anhydrate is supposed to be smaller than the water!
0.047141 g is smaller than 0.4203g.
The last step is to divide by the anhydrate.
0.047141 g / 0.047141 g = 1
0.4203g / 0.047141 g = 8.916 (KEEP IN MIND OF SIG FIGS!!!!!)
