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3/15/12 – Bell ringer

3/15/12 – Bell ringer. Water freezing or boiling is not chemical reaction. Why? Hold on to 4 bell ringers as we will turn them in at the end of notes. Chapter 23 – Chemical Reactions. 23.1 – Chemical Changes. Objectives. 1. Identify the reactants and products in a chemical reaction.

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3/15/12 – Bell ringer

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  1. 3/15/12 – Bell ringer • Water freezing or boiling is not chemical reaction. Why? • Hold on to 4 bell ringers as we will turn them in at the end of notes

  2. Chapter 23 – Chemical Reactions 23.1 – Chemical Changes

  3. Objectives • 1. Identify the reactants and products in a chemical reaction. • 2. Determine how a chemical reaction satisfies the law of the conservation of matter. • 3. Determine how chemists express chemical changes using equations

  4. Chemical Reaction • A change in which one or more substances are converted to new substances • Reactants – the substances that react • Products – the new substances produced

  5. Different Reactions • Chemical reactions – use the ELECTRONS to form new substances • Nuclear reactions - use the NUCLEUS to form new substances • What does a chemical reaction look like?

  6. Chemistry Kitchen

  7. Chemistry Kitchen REACTANTS PRODUCTS

  8. Think about it… • If you burned a piece of paper, you end up with a pile of ashes. • Once burned, is there… • More mass? • Same mass? • Less mass? • Why?

  9. Conservation of Mass • Law that states in a chemical reaction, matter is not created or destroyed • Antoine Lavoisier experimented with mercury (II) oxide and heat • He found mass of products (liquid mercury and oxygen gas) equaled mass of reactants

  10. Chemical Equation • Uses chemical formulas and symbols to describe a chemical reaction and the product(s) it produces • Chemical formula expresses the relationship between elements in the compound and molecules they make up

  11. Chemical Equation Reactants (left) → Products (right) Arrow means “yields” SnO2(s) + 2 H2(g) → Sn(s) + 2 H2O(g) CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)

  12. Coefficients • Numbers which represent the number of units of each substance in a reaction • Knowing coefficients of chemical reactions allows chemists to use the correct amount of reactants to predict the amount of products (law of conservation applies)

  13. Example

  14. Writing equations • Subscripts = Numbers which represent the number of atoms in a molecule of a particular element • Symbols used to show state of reactants • (s) solids • (aq) aqueous • (l) liquid • (g) gas

  15. Volcano with a Twist • Reactants? • Products?

  16. Equation: NaHCO3 ( ) + CH3COOH ( )  CH3COO-Na+( ) + H2O ( ) + CO2( ) • States? • Conservation?

  17. Exit slip on BR paper • SnO2(s) + 2 H2(g) → Sn(s) + 2 H2O(g) • What are the reactants? • What are the products? • How is matter conserved/equalled out? • What changed? • (Compounds and States)

  18. In-class Assignment/Homework • 23.1 WKT

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