Question bank: Ponderal Laws: Introduction

In which scientific area is the Law of Conservation of Masses inserted?

Consider the following experiment: a closed container containing 15 grams of calcium carbonate (CaCO3) is heated, resulting in the decomposition of the compound into carbon dioxide (CO2) and calcium oxide (CaO). After a period of time, the system reaches thermal equilibrium and the formation of 6 grams of carbon dioxide is observed. Based on the Laws of Lavoisier and Proust, and knowledge of balancing chemical equations, answer the following questions: 1. Write the balanced chemical equation for the decomposition of calcium carbonate based on the information that 15 grams of the compound produce 6 grams of carbon dioxide and an unknown amount of calcium oxide. 2. Considering Lavoisier's Law, explain why it is important for the container to be closed and what can be inferred about the total mass of the system before and after the reaction. Also, explain how this information can be used to determine the mass of calcium oxide formed.

One of the fundamental principles of Chemistry is the conservation of mass, stated by Lavoisier's Law, which affirms that 'In nature, nothing is created, nothing is lost, everything is transformed'. This law is essential for the understanding of chemical reactions and is complemented by Proust's Law, which establishes that a pure substance always contains the same elements in fixed and defined proportions by mass. Consider the formation reaction of water from hydrogen and oxygen, which is illustrated by the chemical equation: 2H2(g) + O2(g) -> 2H2O(g). If initially we have 10 grams of hydrogen and 40 grams of oxygen in the container, and after the reaction all the hydrogen is consumed, we want to determine: (1) What is the amount of water formed in grams and what is the mass of oxygen remaining at the end of the reaction? (2) If the reaction continues until none of the excess reactants are left, what will be the total mass of products formed and what is the importance of the principle of conservation of mass in this context?

After a practical chemistry class, a group of students mixed 10 g of zinc (Zn) powder with 25 g of hydrogen sulfide (H2S) in another container. A reaction was observed, and at the end of the experiment, the container weighed 33 g. Based on the observations and knowledge of the ponderal laws of Lavoisier and Proust, answer: (1) What is the product formed in the reaction between zinc and hydrogen sulfide? (2) How does the total mass observed in the container before and after the reaction confirm Lavoisier's Law of Conservation of Mass?

During a chemistry class, the teacher mixed 2 grams of hydrogen (H2) with 16 grams of oxygen (O2) in a closed container. After the reaction, it was observed that all the reactants had completely reacted. The students are required to apply Lavoisier's and Proust's laws of ponderal to understand the conservation of mass and the constancy of the mass proportions of the substances reacting with each other. Considering that the reaction produced water (H2O), which is a substance composed of 2 parts of hydrogen to 16 parts of oxygen, the following is requested: 1. Identify and explain which ponderal law is applied to justify that the total mass of the products formed is equal to the total mass of the reactants. 2. Calculate the mass of water formed in the reaction and verify if the mass ratio between hydrogen and oxygen in water is in accordance with Proust's Law. Consider the atomic masses: H = 1 u and O = 16 u.