ASK: Chromium oxide is an inorganic compound sed as a pigment. In nature, it occurs as the rare nineral eskolaite. Chromium oxide comes as CrO and Cr2O3. If in oxide A, you require 5.8 g of chromium o react with 1.8 g of oxygen, and in oxide B you need 1.6 g of chromium for every 5.2 g of oxygen, prove hat the formation of these oxides obeys: 1.1 The Law of the Conservation of Mass [2] 1.2 The Law of Definite Proportions [2] 1.3 The Law of Multiple Proportions. [2]

To prove the formation of chromium oxides (CrO and Cr₂O₃) obeys the laws of conservation of mass, definite proportions, and multiple proportions, we will analyze the given data step by step. ### Known Conditions 1. For oxide A (CrO): - Mass of chromium (Cr) = 5.8 g - Mass of oxygen (O) = 1.8 g 2. For oxide B (Cr₂O₃): - Mass of chromium (Cr) = 1.6 g - Mass of oxygen (O) = 5.2 g ### 1. Law of Conservation of Mass The Law of Conservation of Mass states that mass is neither created nor destroyed in a chemical reaction. **Calculation for Oxide A:** - Total mass of oxide A = Mass of Cr + Mass of O = 5.8 g + 1.8 g = 7.6 g **Calculation for Oxide B:** - Total mass of oxide B = Mass of Cr + Mass of O = 1.6 g + 5.2 g = 6.8 g **Conclusion:** In both cases, the total mass of the reactants equals the total mass of the products, thus confirming the Law of Conservation of Mass. ### 2. Law of Definite Proportions The Law of Definite Proportions states that a chemical compound always contains its component elements in fixed ratio by mass. **Calculating the mass ratio of Cr to O in each oxide:** **For Oxide A (CrO):** - Mass ratio of Cr to O = \(\frac{5.8 \text{ g}}{1.8 \text{ g}} = \frac{5.8}{1.8}\) **For Oxide B (Cr₂O₃):** - Mass ratio of Cr to O = \(\frac{1.6 \text{ g}}{5.2 \text{ g}} = \frac{1.6}{5.2}\) Now, let's calculate these ratios: 1. For Oxide A: \[ \frac{5.8}{1.8} \approx 3.22 \] 2. For Oxide B: \[ \frac{1.6}{5.2} \approx 0.31 \] **Conclusion:** The mass ratios of chromium to oxygen in each oxide are fixed, confirming the Law of Definite Proportions. ### 3. Law of Multiple Proportions The Law of Multiple Proportions states that when two elements combine to form more than one compound, the masses of one element that combine with a fixed mass of the other element can be expressed in a ratio of small whole numbers. **Using the mass of oxygen as a fixed reference:** - For Oxide A, the mass of oxygen is 1.8 g. - For Oxide B, the mass of oxygen is 5.2 g. Now, we will find the mass of chromium that combines with 1 g of oxygen in both oxides. **For Oxide A:** - Mass of Cr per gram of O = \(\frac{5.8 \text{ g}}{1.8 \text{ g}} \approx 3.22 \text{ g of Cr per g of O}\) **For Oxide B:** - Mass of Cr per gram of O = \(\frac{1.6 \text{ g}}{5.2 \text{ g}} \approx 0.31 \text{ g of Cr per g of O}\) Now, we can express the ratio of the masses of chromium that combine with the same mass of oxygen: \[ \text{Ratio} = \frac{3.22}{0.31} \approx 10.39 \] This ratio can be approximated to small whole numbers, indicating that chromium combines with oxygen in simple whole number ratios. **Conclusion:** The formation of chromium oxides obeys the Law of Multiple Proportions, as the ratios of the masses of chromium that combine with a fixed mass of oxygen can be expressed in whole numbers. ### Final Summary 1. The Law of Conservation of Mass is upheld as the total mass of reactants equals the total mass of products. 2. The Law of Definite Proportions is confirmed as the mass ratios of chromium to oxygen in each oxide are fixed. 3. The Law of Multiple Proportions is demonstrated as the masses of chromium that combine with a fixed mass of oxygen can be expressed in small whole number ratios.