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Questions and Answers
What is the Law of Conservation of Mass?
What is the Law of Conservation of Mass?
Mass cannot be destroyed during a chemical reaction, but is always conserved.
Who established the Law of Definite Proportions?
Who established the Law of Definite Proportions?
Joseph-Louis Proust
What is the molecular weight of water (H2O)?
What is the molecular weight of water (H2O)?
H2O is made up of ___% hydrogen and ___% oxygen.
H2O is made up of ___% hydrogen and ___% oxygen.
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According to the Law of Multiple Proportions, what is the mass ratio of nitrogen to oxygen in nitrogen monoxide (NO)?
According to the Law of Multiple Proportions, what is the mass ratio of nitrogen to oxygen in nitrogen monoxide (NO)?
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The ancient Greek philosopher Democritus believed that atoms could be divided indefinitely.
The ancient Greek philosopher Democritus believed that atoms could be divided indefinitely.
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Which of the following is NOT a fundamental element according to Empedocles?
Which of the following is NOT a fundamental element according to Empedocles?
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What was Aristotle's view of matter?
What was Aristotle's view of matter?
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Match the following ancient philosophers with their contributions:
Match the following ancient philosophers with their contributions:
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Study Notes
Fundamental Laws of Chemistry
- Fundamental laws include the Law of Conservation of Mass, Law of Definite Composition, and Law of Multiple Proportions.
Law of Conservation of Mass
- Mass cannot be created or destroyed in a chemical reaction; it is conserved.
- This law serves as a basis for stoichiometric calculations in determining amounts of reactants and products.
- By the late 1700s, elements were defined as substances that could not be broken down by ordinary chemical means.
Law of Definite Composition
- Proposed by Joseph-Louis Proust, this law states that a chemical compound contains the same elements in the same mass percentage.
- Example: Water (H₂O) comprises 2 hydrogen atoms (1 g/mol each) and 1 oxygen atom (16 g/mol), giving a molecular weight of 18 g/mol.
- In H₂O, the % by weight is approximately 11% hydrogen and 89% oxygen, indicating fixed proportions for formation.
Law of Multiple Proportions
- States that the masses of one element that combine with a fixed mass of another element are in a ratio of whole numbers (e.g., 2:1, 1:1).
- Example: Oxides of nitrogen show different ratios with fixed nitrogen mass (14 g/mol) and varying oxygen masses.
- For different nitrogen oxides like NO, NO₂, and NO₃, the mass ratios of nitrogen to oxygen are consistent and can be expressed in whole numbers.
Nature and States of Matter
- Matter is composed of tiny particles, as concluded by ancient philosophers.
The Particle Nature of Matter
- Early beliefs proposed four fundamental elements: earth, air, fire, and water by Empedocles.
- Leucippus and Democritus introduced the concept of atoms as indivisible particles that form the building blocks of matter.
Key Principles of Atomism
- All matter consists of tiny, invisible atoms which cannot be further broken down.
- Atoms are in constant motion within empty space and are solid entities.
- Atoms possess uniformity and lack internal structure, yet differ in size and shape.
Opposition to Atomic Theory
- Aristotle rejected atomism, favoring the theory of continuous matter composed of four elements and later adding aether as a fifth element.
- Early theories relied on logic without experimental evidence.
Conclusion on Atomic Theory
- Historic theories were disproven with advancements in experimental science.
- Current understanding affirms matter is composed of atoms, which can further break down into subatomic particles.
- The development of subatomic particle characterization led to new scientific fields and ongoing technological progress.
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Description
This quiz explores the fundamental laws of chemistry, including the Law of Conservation of Mass, Law of Definite Composition, and Law of Multiple Proportions. You'll learn how these laws contribute to the formulation of modern atomic theory and understand their application in laboratory experiments.
