Determination of the Empirical Formula of Silver Oxide
9/12 – 9/13
The purpose of this lab is to use one of the ways to identify different compounds and be able to tell them apart. Based off of experimentation, the empirical formula of the given silver oxide will be determined. Materials:
Silver Oxide, 0.5g
Balance, 0.001-g or 0.0001-g precision
Clay pipestem triangle
Crucible and cubicle lid, 15- or 30-mL
Ring stand and ring clamp
Wire gauze with ceramic center
Pre Lab Questions
1. Use molar mass of iron to convert the mass of iron to moles. 85.65g/55.9g 1.534 moles of Iron were used
2. According to the law of conservation of mass, what is the mass of oxygen that reacts with the iron? 118.37g – 85.65g = 32.72 grams of Oxygen reacted with Iron 3. Calculate the number of moles of oxygen in the product. 32.72g/15.99g = 2.045 moles is the amount of moles of Oxygen produced 4. Use the ratio between the number of moles of iron and the number of moles of oxygen to calculate the empirical formula of iron oxide. Fe3O2
Set up a Bunsen burner on a ring stand beneath a ring camp holding a clay pipestem triangle. Place the crucible in the clay triangle. Do NOT light the Bunsen burner. Adjust the height of the ring clamp so that the bottom of a crucible sitting in the clay triangle is about 1 cm above the burner. This will ensure that the crucible will be in the hottest part of the flame when the Bunsen burner is lit. Light the Bunsen burner and brush or gently heat the bottom of the crucible with the burner flame for about one minute. Turn off the Bunsen burner and allow the crucible to cool. Using crucible tongs to handle the crucible, measure the mass of a clean, dry, empty crucible and its lid to the nearest 0.001 g. Record the mass in the Data Table. Using proper transfer techniques, add approximately 0.5 grams of silver oxide sample to the crucible. Measure the combined mass of the crucible, crucible lid, and silver oxide to the nearest 0.001 g. Record the mass in the Data Table. Place the crucible with its lid on the clay triangle. Light the Bunsen burner again and slowly heat the crucible by brushing the bottom of the crucible with the Bunsen burner flame for 2-3 minutes. Place the burner on the rig stand and gently heat the crucible for an additional 10 minutes. After 10 minutes, adjust the burner to maximize the flame temperature. Heat the crucible with the most intense part of this flame for 10 minutes. After 10 minutes, turn off the gas source and remove the burner. Using tongs, remove the crucible lid and place it on a wire gauze on the bench top. With the tongs, remove the crucible from the clay triangle and place it on the wire gauze as well. Allow the crucible and its contents to cool completely on the bench top for at least 10 minutes. Measure the combined mass of the crucible, crucible lid and silver metal product. Record the mass in the Date Table. Record all observations of silver oxide in the Data Table.
Dump the entire contents of the crucible into the waste container provided by the instructor. Carefully clean the crucible and crucible lid three times.
Mass of crucible and lid, g
Mass of crucible, lid, and silver oxide, g
Mass of crucible, lid, and silver metal, g
Appearance of product
Gray Solid powder
Gray Solid Powder
1. Calculate the mass of silver oxide and the mass of silver metal product. Use the law of conservation of mass to calculate the mass of oxygen produced with the silver. Enter the answers in the Data results table. 31.000g – 30.449 = .551g of silver oxide
30.865g – 30.449 = .413g of silver
31.000g - 30.865 = .137g of oxygen
2. What is the percent...