Chemistry 4.2: Conservation of Mass
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Chemistry 4.2: Conservation of Mass

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Questions and Answers

What does the law of conservation of mass state?

That during a chemical reaction, the total mass of the products must be equal to the total mass of the reactants.

What is an element?

A substance that cannot be broken down into a simpler substance by ordinary chemical means.

For any chemical process in an isolated system, the mass of reactants must be ____ the mass of products.

equal to

During a chemical reaction, the total mass of the products must be equal to the total mass of the reactants is stated by the law of _______.

<p>conservation of mass</p> Signup and view all the answers

A reaction between ammonia gas and chlorine gas produces ammonium chloride and nitrogen gas. What mass of ammonium chloride is formed in the reaction?

<p>40.1 g</p> Signup and view all the answers

A reaction of 12.640 g of copper oxide with 0.316 g hydrogen produces 2.844 g of water and X g of copper. What is X?

<p>10.112 g</p> Signup and view all the answers

Magnesium reacts with hydrochloric acid to produce hydrogen gas and magnesium chloride. How much hydrochloric acid was used in the reaction?

<p>74.46 g</p> Signup and view all the answers

2.56 g of hydrogen reacts completely with 20.32 g of oxygen to form X g of water. What is X?

<p>22.88 g</p> Signup and view all the answers

If 100 g of calcium carbonate decomposes to form calcium oxide and carbon dioxide, what mass of carbon dioxide is produced?

<p>44 g</p> Signup and view all the answers

What mass of carbon dioxide gas was produced when 10.0 g of calcium carbonate was heated?

<p>4.4 g</p> Signup and view all the answers

When one or more substances undergo a chemical reaction, what happens to the mass of the product and the reactant?

<p>Mass of the product and reactant remains the same.</p> Signup and view all the answers

What is the total mass of ammonia and water vapor produced when 5.00 g of calcium hydroxide reacts?

<p>13.73 g</p> Signup and view all the answers

A reaction of 22.85 g of sodium hydroxide with 20.82 g of hydrogen chloride produces X g of sodium chloride. What is X?

<p>33.38 g</p> Signup and view all the answers

What mass of oxygen gas was produced in the reaction of heating potassium permanganate?

<p>1.6 g</p> Signup and view all the answers

According to the law of conservation of mass, if an atom of element A has a mass of 2 units, while an atom of element B has a mass of 5 units, what would be the mass of the compound A3B2?

<p>16 units</p> Signup and view all the answers

Matter is not conserved in chemical reactions.

<p>False</p> Signup and view all the answers

Mass is always conserved in chemical reactions.

<p>True</p> Signup and view all the answers

According to the law of conservation of mass, mass is always conserved in a chemical reaction.

<p>True</p> Signup and view all the answers

Lavoisier discovered the principle of conservation of mass in chemical reactions.

<p>True</p> Signup and view all the answers

The law of conservation of mass states that in conventional chemical reactions matter can not be ___ or destroyed, only rearranged.

<p>created</p> Signup and view all the answers

Mass is conserved in physical but not chemical changes in matter.

<p>False</p> Signup and view all the answers

Study Notes

Law of Conservation of Mass

  • States that the total mass of products equals the total mass of reactants in a chemical reaction.
  • Mass cannot be created or destroyed, only conserved.
  • Principle established by Antoine Lavoisier.

Definitions

  • Element: A substance that cannot be simplified further by ordinary chemical processes.
  • Chemical Reaction: Process wherein substances interact to form new products while conserving mass.

Key Principles

  • Mass of reactants must always match mass of products in an isolated system.
  • The total mass is unchanged during any reaction, whether physical or chemical.

Examples

  • Ammonia (17.0 g) + Chlorine (26.6 g) yields Nitrogen (3.5 g) resulting in 40.1 g of Ammonium Chloride.
  • Copper Oxide (12.640 g) + Hydrogen (0.316 g) produces Water (2.844 g) and Copper (10.112 g).
  • Magnesium (24.48 g) reacts with Hydrochloric Acid to produce 2.04 g of Hydrogen and 96.90 g of Magnesium Chloride, requiring 74.46 g of Hydrochloric Acid.

Calculations

  • Water formed from 2.56 g Hydrogen and 20.32 g Oxygen totals 22.88 g.
  • Decomposition of Calcium Carbonate (100 g) yields Calcium Oxide (56 g) and Carbon Dioxide (44 g).
  • Heating Calcium Carbonate produces 4.4 g of Carbon Dioxide gas from 10.0 g of initial reactants.

Misconceptions

  • Matter is conserved during chemical reactions.
  • When water freezes, the mass of ice remains equal to the mass of water.
  • Mass conservation applies to both physical and chemical changes.
  • The statement that mass is not conserved in chemical reactions is false.

True/False Statements

  • Mass is conserved in chemical reactions - TRUE
  • Matter conservation in chemical reactions - TRUE
  • Mass can be created or destroyed in chemical reactions - FALSE
  • Mass is conserved in physical changes but not in chemical changes - FALSE

Additional Information

  • The law applies to both closed systems in chemical reactions and physical changes, thereby affirming its fundamental nature in chemistry.

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Test your knowledge on the Law of Conservation of Mass through these flashcards. This quiz covers essential definitions and concepts related to chemical reactions, emphasizing that mass is neither created nor destroyed. Perfect for reinforcing your understanding of fundamental chemistry principles.

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