1. Grab…
handouts on door
calculator from front desk
2. Begin the Do Now
Do Now
Use your notes to help you!
1.When converting from moles to mass, what
do you multiply the number of moles with?
2.When converting from mass to moles, what
do you divide the mass by?
3.What are the units for molar mass?
Stoichiometry
- Mass to Moles:
moles x molar mass
- Moles to Mass:
mass ÷ molar mass
- Moles of X to Moles of Y:
moles x mole ratio
Pre-Lab Practice: Moles  Mass
1. How many grams are in 2 moles of H2O?
2. How many grams are in 3 moles of CH4?
3. How many grams are in 5 moles of HF?
Aspirin Lab
How do you compare bottled water to water
from EPIC’s water fountains?
How can we determine what’s good and what’s
bad?
Lab Question
Are brand name commercial prescription drugs
better than homemade prescription drugs?
While you wait…
Start you lab report
using your Lab Report Format sheet….
-Purpose: What are we determining and how?
-Hypothesis: Which do you believe is more pure
and why?
Theoretical Yield
C7H6O3(s) + C4H6O3(aq)  C9H8O4(s) + C2H4O2(aq)
How much did we start with?
Molar Masses?
Mole Ratio?
Lets climb up & down the mole hill…
Percent Yield & Percent Error
Percent Yield: How much product you obtained
Percent yield = (actual yield ÷ theoretical yield) x 100%
Percent Error: How accurate you were
Percent error = | actual yield – theoretical yield | x 100 %
theoretical yield
Conclusion
Restate the purpose
Explain your hypothesis (accepted or rejected?)
Results – use your results to answer the
purpose!
Unknown – what were some unexpected errors
that occurred? If your percent yield
was not 100%, then why?
New – what can you change if you were to
perform this lab again?
Climbing the Mole Hill
Let’s Put it all together:
2H2O2(aq)  2H2O(l) + O2(g)
1. If you start with 6 grams of H2O2, how many
grams of O2 will you produce?
2. If you produce 36 grams of H2O, how many
grams of H2O2 did you start with?