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Pre-Lab Qs - Experiment 4

Pre-Lab Qs - Experiment 4 - Jöns Jakob found when 10.0...

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Name:__________________________ Quiz (1) ___________ (1 pt) (2) _____________(1 pt) Chem 102: Prelab Worksheet for Experiment 4. Do to many factors, green chemistry being only one, you will not repeat a classic experiment that illustrates Proust’s/ Dalton’s law of definite proportions/ multiple proportions. These laws state compounds contain elements in defined proportions. For example, lead (II) sulfide (PbS) and lead (IV) sulfide (PbS 2 ) are two different compounds because the ratio of lead to sulfer in each is different. The molar ratio of lead (II) sulfide (PbS) is 1:1, while the molar ratio is 1:2 in lead (IV) sulfide (PbS 2 ). In 1828 Jöns Jakob Belzelius was busy generating experimental data that supported the law of definite proportions. He heated lead, a soft, blue-gray metal (atomic mass 207.2), and sulfer, a yellow nonmetal (atomic mass 32.066), to form lead (?) sulfide.
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Unformatted text preview: Jöns Jakob found when 10.0 grams of lead was heated with 1.55 grams of sulfer he obtained 11.55 grams of lead (?) sulfide. Did Jöns Jakob form lead (II) sulfide (PbS) or lead (IV) sulfide (PbS 2 )? (The question is base on a description of historical events found in Hill and Kolb, Chemistry for Changing Times, 2007, page 40-41. You may refer to this reference, but it will not aid in answering the question.) Calculate the moles of Pb in 10 grams of Pb (2 points) Calculate the moles of S in 1.55 grams of S (2 points) Calculate the molar ratio of Pb to S (2 points) Jöns Jakob made (circle one, 2 points) lead (II) sulfide (PbS ) OR lead (IV) sulfide (PbS 2 ) *****NOTE. You will have a two-point quiz at the start of the lab regarding safety precautions. You will place your answers to the quiz on the top of this sheet when you take the quiz at the start of lab. NOTE*****....
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