Exp 04: Chemical Formula
Your job is to react copper wire (Cu) with sulfur powder (S8) using heat
from a bunsen burner to form a copper sulfide compound.!
Then to determine and justify the molecular formula of that compound.
CuXSY
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C4: Calculate the empirical formula for the copper sulfide you formed. C5: Theoretically, two copper sulfides can exist. One has a molecular weight of 159.157 ...
Typology: Exams
2022/2023
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Your job is to react copper wire (Cu) with sulfur powder (S8) using heat
from a bunsen burner to form a copper sulfide compound.
Then to determine and justify the molecular formula of that compound.
CuXSY
Procedure
- Support a clean, dry, porcelain crucible and cover on a clay triangle and dry by heating to a dull red in a Bunsen burner flame. Allow the crucible and cover to cool to room temperature and weigh them. Record the mass to the nearest 0.01 g.
- Place 1.5 to 2.0 g of tightly wound copper wire or copper turnings in the crucible and weigh the copper, crucible, and lid to the nearest 0.01 g and record your results. Calculate the mass of copper.
- In the hood, add sufficient sulfur to cover the copper, place the crucible with cover in place on the triangle, and heat the crucible gently until sulfur ceases to burn ( blue flame) at the end of the cover. Do not remove the cover while the crucible is hot.
- Heat the crucible to dull redness for about 5 minutes.
- Allow the crucible to cool to room temperature. This will take about 10 min. Then weigh with the cover in place. Record the mass.
- Again cover the contents of the crucible with sulfur and repeat the heating procedure. Allow the crucible to cool and reweigh it. Record the mass. If the last two weighings do not agree to within 0.02 g, the chemical reaction between the copper and sulfur is incomplete. If this is found to be the case, add more sulfur and repeat the heating and weighing until constant mass is obtained.
- Calculate the mass of copper sulfide obtained. The difference in mass between the copper sulfide and copper is the mass of sulfur in copper sulfide. Calculate this mass. From this information the empirical formula for copper sulfide can be obtained, and the chemical equation for its production can be balanced.