(Originais Teachy 2024) - Question Hard of Sciences

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?