Applying-Principles-of-Conservation-of-Mass-to-Chemical-3.pptx

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1. Applying Principles of Conservation of Mass to Chemical Reaction

2. Chemical Reactions Chemical reactions are all around us and we experience them everyday and everywhere. Combustion reactions help release energy to heat our homes and our vehicles, heat popcorn, or bake a cake, etc. In the process of photosynthesis in which carbon dioxide and water are changed into sugars by plants and rotting of fruits and vegetables. 2

3. Chemical Processes Decomposition of waste also involves chemical processes. Oxidation-reduction reactions keep the batteries in our cell phones and laptops functioning. Acid-base reactions take place when cleaning your oven or removing clog from a drain. Acid-base reactions are also the basis for the titrations experiment where you will measure the acidity of fruit juices. 3

4. Laws of Chemical change Law of Conservation of Mass This law is also known as the Lomonosov-Lavoisier law, states that the quality of mass of substance remains constant regardless of any change that takes place. The mass of the reactants must always be equal to the mass of the products. 4

5. Laws of Chemical change 2. Laws of Definite Composition This law was first observed by a French chemist, Louise Proust, then after fifty years, Jean Servais Stas experimentally confirmed Proust’s observation. It states that elements combined to form compound always contains exactly the same proportion of elements by mass. 5

6. Laws of Chemical change 3. Law of Multiple Proportion This law sometimes called the Dalton’s Law, after its discoverer. It states that if two elements form more than one compound , the ratios of the masses of the second element combining with a fixed mass of the first elements will be in ratio of small whole numbers. 6

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8. Chemical Equation Since the actual details in chemical reaction are not visible in our eyes, it can be explained through writing. Chemical equation is used to illustrate a chemical reaction using symbols, formulas, and signs. It is the chemists’ shorthand for describing the sequence of a chemical reaction . 8

9. Writing Chemical Equation Chemical formulas of element symbols are used instead of names. This consists of the reactants (written on the left side of the equation) and products (written on the right side ). In between the two reactants, the + sign is used in place of the word and. 9

10. Writing Chemical Equation 4. To separate the reactants and the products, and arrow (— ˃) is placed in between them, the tip of an arrow indicates the direction of the reaction and this represents the word produce, yield or form. 5. There should be the same atoms on the reactant and the product side of the equation. 10

11. 1. Combination or Synthesis Reaction In a combination or synthesis reaction, two or more substances (either elements or compounds) react to form one product. The general formula for combination or synthesis reaction is: A + B  AB 11

12. 12 CO2 + H2O → O2 + C6H12O6

13. CO 2 + H 2 O → O 2 + C 6 H 12 O 6

14. 2. Analysis or Decomposition Reaction If something decomposes, it breaks down into smaller parts. Decomposition reaction is a reaction in which single compounds is broken down into two or more smaller compounds or elements. This reaction is the reverse of the combination reaction. The general form for decomposition reaction is: AB  A + B 14

15. H 2 C0 3 → CO 2 + H 2

16. 3. Single Replacement (Substitution) reactions In a single-replacement reaction, an uncombined element displaces an element that is part of a compound. The reactants in a single-replacement reaction are always one element and one compound. The general form for a single-replacement reaction is: A + BX  AX + B 17

17. 4. Double-Replacement (or Metathesis) Reactions In a double-replacement reaction, atoms or ions from two different compounds replace each other. An identifying characteristics or a double-replacement reaction is the presence of two compounds as reactants and two compounds as products. The reactants in a double-replacement reaction are generally ionic compounds. The general form for a double-replacement reaction is: AX + BY  AY + BX 19