Stoichiometry Generator



Stoichiometry Generator!



2NH3 + CO2 ⋄ (NH2)2CO + H2O

Ammonia carbon dioxide

The “stoichiometry applet” is a visual representation of what occurs when reactants form products for the reaction above. You can adjust the amount of each reactant in grams and moles, and then pull the slider bar across to see how much product is formed.

Using the Applet:

1. You can change the amount in moles or grams of the reactants by right-clicking once on the amount. A small box will come up, and you can input by typing in the value you wish. If you have problems with the right clicking, click near the base of the bars.

2. Find the moles panel and right click on the first reactant, NH3. Put into this box 200 moles. Click on “okay”. On the other reactant, CO2, do the same, but input “100 moles”. Click okay. Make sure that the two products are set at “zero”.

3. Now, pull the slider bar across the bottom of the panel and observe what happens to the quantities of the reactants and products.

Does the ammonia disappear as quickly as the carbon dioxide? _____________

4. Push the slider bar halfway, so that there are 50 moles of carbon dioxide left.

Now, how many moles of ammonia are left? ___________

How many moles of the two products have been formed? _______

5. Now, push the slider all the way to the right so that both reactants are gone.

How many moles of each reactant have been formed? _________

What is the mole ratio of ammonia to carbon dioxide in the chemical formula? ________________

What is the mole ratio of the two products relative to one another? _________

As the products are being formed, are they formed in this ratio? __________

6. You will notice that the ratio of mass for the reactants change, too, as you push the slider bar. Is this mass ratio the same as the mole ratio? ___________

7. Now, reset your mole bar for the ammonia, NH3 so that now you have 400 moles instead of 200. Now, slowly slide your bar across to the right. When it is pushed all the way to the right, observe the amount of all reactants and products.

How many moles of ammonia are left over? __________

How many moles of each product are formed? ___________________

The reactant carbon dioxide ran out before the ammonia. Is this case, the carbon dioxide is the limiting reactant because it limits the amount of product that can be formed, since it will be used up first. The reactant that is left over is called the excess reactant. In many of our laboratory reactions, one of the reactants is usually used in excess so that the reaction will go to completion.

You will now set up the following situations and determine in each case, which is the

limiting reactant.

Using the Stoichiometry Applet for Mass to Mass Problems

Set the bars for 2 moles of NH3, and 1 mole of CO2.

What is the mass shown above for each of the two reactants? ________________

What is the mass shown above for each of the two products? ________________

If you add the masses of the two reactants together, you get _____, and if you add the masses of the two products you get _____. What does this tell you about the relationship between the masses of reactants and products in a chemical reaction? _____________________________________________________________

Use the balanced chemical equation on the front page, your periodic table, and calculator to solve the following problem:

You are given 2.3 moles of NH3. How many grams of NH3 do you have? _______

How many moles of carbon dioxide will be needed to react completely with 2.3 moles of NH3? _____________

How many grams of carbon dioxide will this be? _________

Now, check yourself using the applet by inputing 2.3 moles of NH3, and the number of moles of carbon dioxide you found. Check the masses above the bars to see if this is correct.

Now, examine the mass of the carbon dioxide and see if it is correct.

How many grams of each product should be produced according to the applet? ______________ and ____________.

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|NH3 |CO2 |(NH2)CO |H2O |Limiting Reactant? |Moles of Excess Reactant Left |

|500 moles |300 moles | | | | |

|600 moles |1300 moles | | | | |

|350 moles |350 moles | | | | |

|62 moles |30 moles | | | | |

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