University:
Ball State University
Course:
CHEM 111 | General Chemistry 1
Academic year:

2023
Views:

134

Pages:

2
Author:

michelle kh.

Law of Fixed Comparison (Proust's Law) In 1799, Joseph Louis Proust discovered an important property of compounds, which is called the law of fixed proportions. Based on research on various compounds that he did, Proust concluded that "The ratio of the masses of the elements in a compound is certain and still." The same compounds even though they come from different regions or are made in different ways it turns out to have the same composition. An example of determining the mass ratio of the elements in a compound as follows. Table below shows the experimental results of the reaction of iron with sulfur form iron sulfide (FeS). Based on these data it turns out that the mass ratio of iron and sulfur in iron sulfide (FeS) compounds is always constant, namely 7 : 4. Data on the reaction between hydrogen and oxygen to form water, if known The mass ratio of H : O to form water is 1 : 8 as follows. Example : It is known that the mass ratio of calcium and oxygen in forming calcium compounds oxide is 5 : 2. If 10 grams of calcium and 12 grams of oxygen are reacted, determine mass of calcium oxide (CaO) formed and the rest of the reactants! Answer : Exercise 1. Solve the following questions like examples! 1. The mass ratio of carbon (C) to oxygen (O) in carbon dioxide compounds (CO2 ) is 3 : 8. How many grams by mass of carbon dioxide are formed and the remainder reagent, if reacted: a. 6 grams of carbon with 16 grams of oxygen b. 6 grams of carbon with 8 grams of oxygen c. 3 grams of carbon with 10 grams of oxygen d. 12 grams of carbon with 24 grams of oxygen 2. The mass ratio of Fe : S in FeS compounds is 7 : 4. What is the mass of FeS formed and the remaining mass of the reactants, if reacted 35 grams of iron and 16 grams sulfur? 3. If 1 gram of substance X is reacted with 3 grams of substance Y , it forms 2.33 grams compound XY, what is the mass ratio of elements X : Y in the XY compound 4. It is known that the mass ratio of copper and oxygen in CuO compounds is 4 : 1. Determine the mass of CuO formed and the remaining reactant, if it is reacted: a. 8 grams of copper with 2 grams of oxygen b. 12 grams of copper with 3 grams of oxygen c. 20 grams of copper with 10 grams of oxygen d. 32 grams of copper with 5 grams of oxygen