Course: Stoichiometry

Unit 12 - Stoichiometry

Topic 1 - Equations and ratios

Welcome to Stoichiometry!!!

It is time to apply what you learned with balancing equations and apply that mathematically.

First Topic ----> Getting ratios from equations! View the pages and the video below. Make sure that you completely understand them before moving to Topic 2.

Topic 2 - Chemical Equations and Mole Ratios

This topic is all about using chemical equations to get mole ratios of reactants and products.

First, watch the video on obtaining mole ratios from balanced chemical equations. Then, practice your mole ratios with the Java Activity.

When you are sure you understand everything, take the quiz!!! It is on Topics 1 & 2!

Topic 3 - Using Mole - Mole Calculations

Those mole ratios are good for something...

Now it is time to put those mole ratios to good use and use them to solve problems involving chemical reactions.

This topic starts you off by calculating moles of products and reactants in a chemical reaction. Understand Topic 3 before moving to Topic 4....you'll understand why later.

Read up on mol - mol calculations, watch the video on the same topic, and complete the assignment. Make sure to turn in the assignment!

Topic 4 - Mass to Mass Calculations

Things will start to get a bit tougher here. This is a very common part of chemistry, meaning that it is what scientists do every day.

If you start with so many grams of a substance, and it undergoes a chemical reaction, how many grams of something else will be needed or produced?

The first thing you should do is get used to the chemistry road map and learn how to use it to perform a mass - mass calculation.

(Try these sample problems on your own before viewing the answers.)
Problem for Example #2:

NH_4NO_3 -----> N_2O + 2 H_2O
• How many g of H_2O are produced when 33.0 g of N_2O are also produced?

Problem for Example #3:

Mg + HCl -----> MgCl_2 + H_2
•If 10.0 g of H_2 is produced, how many grams of HCl reacted?

Problem for Example #4:

• Silver nitrate reacts with copper metal to form silver metal and copper (II) nitrate. If 100.0 g of copper metal is reacted with silver nitrate, how many grams of silver metal precipitate?

The more examples of mass - mass problems and the endless mass-mass problems are there for you to practice with...there is nothing to turn in with these sections. When you are ready, complete and turn in Assignment #2 (mass-mass homework). Finally, take the quiz on Topics 3 & 4 when you've gotten mol-mol and mass-mass calculations down to a T!

Topic 5 - Other Stoichiometric Calculations

Problem - The previous road map was not 100 % complete. Unfortuantely, you are responsible for knowing how to use the "more complete" road map. It can be confusing, so these first few activities are designed around that "more complete" road map.

Read about how the new road map is used, watch a Prezi on calculations that use the new road map. Finally, take a Java self quiz on using the road map.

Once you are sure you know how to use the road map, try out the sample problems.

Problem from Example #1:
The following reaction is often used as a step to produce nitric acid from ammonia:
NH_3(g) + O_2(g) -----> NO_(g) + H_2O_(g)
Determine the mol of water formed by reacting 824 g of NH_3.

Problem from Example #2:
Potassium reacts with fluorine gas to produce potassium fluoride. How many L of fluorine gas are required at STP to produce 12.04 x 10^23 formula units (“molecules”) of potassium fluoride?

The other example problems are for your practice. Complete and turn in Assignment #3. When you are 100% sure you know everything about the "more complete" road map, take the quiz on Topics 3 - 5 (mol-mol, mass-mass, and all road map calculations).

Topic 6 - Limiting Reagent

Now that you are a master at calculating masses of products & reactants, it's time to apply them to a new concept. Look at the balloons in the picture. They were filled up with gas generated by a chemical reaction in between acid & metal in the flask. Each flask had the same amount of acid, but more metal was used in each subsequent reaction (going from left to right). Why are the 3rd and 4th balloons the same size if the 4th reaction used more metal reactant?

This topic may require some hard work...it is all about the concept of the limiting reagent. Start below by viewing a video that shows how the limiting reagent compares to cooking a recipe with a set amount of ingredients in your house. Then, read a brief introduction to the concept of the limiting reagent. Finally, try out the simulation activity to become more acquainted with the concept. It will then be time to start performing math.

You need to perform a chemical reaction. You only have so much of reactant A and so much of reactant B on hand. If you mix them both together to react, which one will run out first? Gotta be able to figure this out before you can proceed with the rest of the problems. View these examples, then try the almost endless limiting reagent problems. Make sure you are a master before moving on in this topic.

It's a good idea to use the limiting reagent and other stoichiometry concepts to check to see how much product will be formed. Else, the reaction could go gangbusters like what created the destruction in the picture on the right.

View the sample problems and do the 2nd simulation activity. This one is an assignment that you must turn in.

You know how to figure out which reagent runs out in a reaction and you know how to calculate how much product will be formed. The last thing you have to do is determine how much of the reactant that is not limiting (excess reagent) is left over. Last part of this topic. View the examples and move on once you understand them.

Feel free to complete the limiting reagent sample problems. Complete and turn in Assignment #4 (limiting reagent problems). Once you feel that you have mastered the concept of the limiting reagent, take the quiz.

Topic 7 - % Yield

The test tubes on the right appear to contain more than one substance. Each tube is likely a mixture of products & reactants. It is uncommon for a reaction to use up all of even one reactant. Chemists like to compare how far the reaction "proceeds" to how far "it could have proceeded." That is called the percent yield....and it is your last topic in stoichiometry!!

Check out the percent yield introduction and the example problems so that you become a master at calculating a reaction's percent yield.

The other percent yield examples and the endless percent yield problems are available for you to practice. Make sure you complete Assignment #5 and turn it in when you are finished. Take the quiz on Topic 7 (percent yield) when you are ready.

Pretest

Complete the pretest before you take the exam. The answers are attached to the pretest, so be sure to check your answers! You will not be handing in the pretest. It covers MOST of the required material, so you may want to review all topics before proceeding to the exam.

Stoichiometry Exam

This is it! Proceed when ready, and GOOD LUCK!!!