All calculations about how much of a chemical to use for a reaction are based on stoichiometry. Chemists who developed airbags in cars had to determine exactly how much of a chemical to use so that the bag would inflate quickly enough. They also had to design it to produce the exact right amount of gas so that the bag would not over- or underinflate.
Don't forget to balance the equation!
Transcript
1.
Shhhh… Don’t say the “S” word! (But what is the “S” word in Chemistry?)
Given the unbalanced equation: Mg(ClO 3 ) 2 -> MgCl 2 + O 2 What is the coefficient of O 2 when the equation is balanced correctly using the smallest whole number coefficients?
Recognizing: given is either in grams or liters; unknown is also in either one
Practice:
C 3 H 8 + O 2 CO 2 + H 2 O What volume of CO 2 gas can be produced when 150.0 g of propane are burned? 229.1 L CO 2 Any time you calculate an amount of product from a balanced equation, this is called “ Theoretical Yield ” 5 3 4
Percent yield is a calculation to determine the efficiency of a chemical process.
Formula:
% yield = (actual yield/theoretical yield) x 100
Practice: During an experiment, a student produced 63.0 g of copper. According to his calculations, he should have made 68.0 g. What was his percent yield?
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