chemical reactions and conservation of mass. a chemical reaction can be represented by a word...
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![Page 1: Chemical Reactions and Conservation of Mass. A chemical reaction can be represented by a WORD EQUATION. Example: Hydrogen gas + Oxygen gas Water Reactants:](https://reader035.vdocument.in/reader035/viewer/2022072006/56649f455503460f94c665c0/html5/thumbnails/1.jpg)
Chemical Reactions and Conservation of Mass
![Page 2: Chemical Reactions and Conservation of Mass. A chemical reaction can be represented by a WORD EQUATION. Example: Hydrogen gas + Oxygen gas Water Reactants:](https://reader035.vdocument.in/reader035/viewer/2022072006/56649f455503460f94c665c0/html5/thumbnails/2.jpg)
A chemical reaction can be represented by a WORD EQUATION.
Example:Hydrogen gas + Oxygen gas Water
Reactants:the starting materials
Products:The ending materials
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Test Reaction:Iron (III) nitrate + sodium iron (III) hydroxide + sodium hydroxide nitrate
1. Place reactants in CLOSED (sealed) flask. 2. Measure mass before reacting.3. Measure mass after reacting.
How will the mass of the reactants in a chemical reaction compare with the mass of products?
Why is it important that the container be closed?So no materials can escape or be added to the system!
Question:
Procedure:.
DEMONSRATION: Allow chemicals to react in a CLOSED container
![Page 4: Chemical Reactions and Conservation of Mass. A chemical reaction can be represented by a WORD EQUATION. Example: Hydrogen gas + Oxygen gas Water Reactants:](https://reader035.vdocument.in/reader035/viewer/2022072006/56649f455503460f94c665c0/html5/thumbnails/4.jpg)
Initial Mass before reaction: (g) Predicted Mass after reaction: (g)
Measured Mass after reaction: (g) Explanation:
Prediction and Observation:
Summary: The mass before and after the reaction is the same.
This is because the number of atoms stays the same. The atoms are rearranged but are NOT created or destroyed!
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Law of Conservation of Mass
In a chemical reaction, the mass of the reactants is equal to the mass of the products. Applying Conservation of Mass : How many grams of oxygen reacts with 40 g of calcium oxide to produce 100 g of calcium oxide?
Calcium + Oxygen → Calcium Oxide 40 g ? 100 g
Ans: Mass of oxygen = 100 g – 40 g = 60 g
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A CHEMICAL EQUATION uses chemical symbols to represent a reaction:
Hydrogen gas + Oxygen gas Water
H2 + O2 H2O This is called a skeleton equation- the number of atoms on either side are not balanced!
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H2 + O2 H2O
To balance the equation, we need to add balancing coefficients in front ofthe terms!
Atom Left Side Right Side Balanced ?
H
O2 2
2 1
2
244
2