CP Chemistry
Homework: Percent Composition and Mole Conversions
Name: _____________________________________ Date: _________________ Class: ______
Part I: Conceptual Questions
Answer the following questions in complete sentences.
#1) When you are asked to calculate the percent composition of a compound explain in detail
what you are calculating.
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#2) Explain the steps that you need to take to calculate the percent composition of glucose
C6H12O6. (You don't need to calculate the actual percent composition here but explain what you
would need to know and do)
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#3)Does the percent composition of a substance change depending on the mass of the sample?
For example if you had 1.00 g or 100.00 g of table salt would the percent composition of table
salt change? Explain.
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#4)After purchasing food from your local grocery store you receive a receipt on each item and
its price that you've bought. How is the concept of percent composition similar to receiving
your grocery bill receipt. What is another analogy or comparison that is similar to the concept
of percent composition?
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Part II Calculation: Round each value and final answer to the nearest hundredths place.
#5) Calculate the percent composition by mass of sodium in sodium sulfate, Na2SO4.
#6) Calculate the percent composition by mass of carbon in iron (III) acetate, Fe(C 2H3O2)3.
#7) During the 1840's California gold rush, miners discovered a 250.00 g sample of fake gold
called pyrite,FeS2. How many grams of sulfur are in the 250.00 g pyrite sample?
#8) A sample of gold (III) dichromate Au2(CrO7)3 is 37.84% gold and 32.28% oxygen by mass.
a) What percent of gold (III) dichromate is made of chromium by mass?
b) How many grams of chromium would be present in a 100.00 gram sample of gold (III)
dichromate?
c) How many moles of chromium would be in a 100.00 gram gold (III) dichromate sample?
d) How many Cr atoms would be in the 100.00 gram gold (III) dichromate sample?