Chem 107 Section _____ Group # _____
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(Estimated time: 35 min)
Exp 5.1 – Introduction to Stoichiometry
Reader read all of the following lab manual pages to your group.
Manager insure members are filling their roles and help everyone finish on time. Contact the
instructor if your team has any questions or problems with the assignment.
Technician perform any experiment(s)/measurements for your group (including the use of the
periodic table), share results with the group.
Recorder record the results and answers into the lab manual. Be ready to share your group’s
answers with the class. “Print” the form to save it and share it with your group.
We know that we balance chemical equations because of the law of conservation of matter, which tells
us that matter cannot be created or destroyed, what we have not talked about is why we spend so
much time talking about it and practicing it. Is there more to it than simply showing that we conserved
matter?
Let’s pick up where the prelab left off.
Figure 1: Ratios with S’mores
1) How many Cs6 are needed to make one Sm?
2) How many Cs are needed to make one Sm?
3) How many Gc2 are needed to make one Sm?
Example 1:
Example 2:
2 Gc
2
(s)
+ 1 Mm
(s) +
1 Cs
6 (s)
1 Sm
(s)
Gc = graham cracker piece
Mm = marshmallow Cs = chocolate square
Sm = S’more
2 NaOH
(aq)
+ 1 H
2
SO
4(aq)
1 Na
2
SO
4(aq)
+ 2 H
2
O
(l)
= Sodium ion = hydroxide ion
= hydrogen ion = sulfate ion
5
1
4
2
