Chemistry Week 4

Make sure to take notes on the videos

We are looking at the ratio science called stoichiometry.

Vocabulary (know the definitions)

Day 1: Watch the Videos

What questions do you have from the earlier videos?
- Try to find the answers to those questions
You need to make sure you can find a limiting reaction or an excess reaction.
- If you need to watch more videos: Step by Step Stoichiometry Practice Problems

You will want to start by picking out a group of ingredients, four or five, that you would like to have in your trail mix.
Using the largest ingredient first, if you can, weight it.
- If you cannot weigh the items put them in the order of your favorite item to your least favorite.
Now we need to establish our ratio… how much of each item do you want?
- 1 Hershey kiss to 2 raisins to 7 rice krispies to 1 dried cherry.
- Now I know that you don’t want to count out;

This would be what you might take with you on a walk around the block but how do we get the receipt right?
- Alchemist would indeed count them out but you are 21 century scientist so we will use stoichiometry.
If you know the average weight of each item you are putting in your mix you can set your scale and pour items onto the scale til it hits zero and you can then put it into the baggie.
- So if a HK weights .9 grams you can set your scale to 9 grams pour HK on until it’s zeroed and then move on.
- Why is this better then counting?
- How do you know how much weight for each item?
- How do you think they make trail mix to sell commercially?
- Do you think they count out home many raisins go in each box of raisin bran? If not how do they know the percentage of the box that is raisins?

Stoichiometry is used in almost every industry and especially in the packaging industry.
It is also used in measuring out how many moles of a material go into making up chemical compounds.
Of all the things we have done in chemistry this one is the most used in good paying jobs you might get.

When you are done write up a short paper explaining what you learned from this activity and place the cookies on the bottom of the page.
- Take a picture and send it to: bartlett@wcskids.net
Make sure to include your name, hour and week 3.
Make sure I get your work by next Saturday