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1. Conservation of Mass

   8C investigate and identify the law of conservation of mass.
2. Conservation of Mass Both the mass and the number of atoms must be equal on both sides of a chemical equation. If you start with 5 atoms of “O” → → You must end with 5 atoms of “O” The total mass on the left side must = the total mass on the right side of the equation.
3. Conservation of Mass The Law of Conservation of Mass states that in a chemical reaction the mass of the reactants must equal the mass of the products. Notice there is more O2 in the products than in the reactants. So this does not demonstrate the law of conservation of mass. C + H2→ CH4
4. Conservation of Mass The Law of Conservation of Mass states that in a chemical reaction the mass of the reactants must equal the mass of the products. Notice there now is an equal amount of H2 in the products and the reactants. So this equation now demonstrates the law of conservation of mass. C + 2H2→ CH4
5. Reactants Products Diatomic gas Needs more Hydrogen Needs more Oxygen
6. Reactants Products
7. Reactants Products Diatomic gas Needs more Hydrogen
8. Reactants Products Diatomic gas
9. Reactants Products Needs more Iron Needs more Chlorine Needs more Hydrogen Needs more Hydrogen Needs more Chlorine
10. Reactants Products
11. Reactants Products We need more Calcium here. We need more Hydrogen and Phosphate here We need more Chlorine here.
12. Reactants Products
13. Reactants Products We need more Ammonium Now we need More Chlorine here
14. Reactants Products
15. 1. The first equation represents photosynthesis. Plants use energy from sunlight to produce sugar and oxygen from carbon dioxide and water. The second equation represents aerobic respiration. Plants and animals release stored energy in a reaction between sugar molecules and oxygen. This reaction produces carbon dioxide and water. To produce 4 molecules of sugar, a plant needs — 6 molecules of hydrogen 12 molecules of ATP 18 molecules of water 24 molecules of carbon dioxide [Default] [MC Any] [MC All]
16. 2. What are the coefficients that will balance this chemical equation? 2, 1, 1 3, 4, 2 2, 2, 1 4, 3, 2 [Default] [MC Any] [MC All]
17. 3. The illustrations show a conservation-of-mass experiment. The solution in the beaker lost mass because — materials have less mass at high temperatures the mass of the reactants and products was less than 100 g sodium sulfate (Na2SO4) is lighter than air some of the water molecules turned into gas [Default] [MC Any] [MC All]
18. 4. What coefficient values will balance the reaction shown above? 2, 2, 1 1, 1, 1 2, 1, 2 1, 2, 2 [Default] [MC Any] [MC All]
19. 5. In the procedure shown above, a calcium chloride solution is mixed with a sodium sulfate solution to create the products shown. Which of the following is illustrated by this activity? The law of conservation of mass The theory of thermal equilibrium The law of conservation of momentum The theory of covalent bonding [Default] [MC Any] [MC All]
20. 6. Two students added a piece of zinc to a solution of hydrochloric acid in an open beaker. The mass of the products was found to be less than the total mass of the reactants. Which of the following statements best explains the loss of mass? Zinc metal is more dense than the acid. The chemical activity of the acid destroyed metal atoms. A gas was released during the reaction. Some of the zinc atoms failed to react. [Default] [MC Any] [MC All]
21. 7. Iron reacts with oxygen in the air to form iron oxide. The unbalanced equation for this reaction is shown above. What are the coefficients when this equation is balanced? 2, 2, 1 2, 3, 1 4, 3, 2 4, 2, 2 [Default] [MC Any] [MC All]
22. 8. If 43.7 g of iron is completely used in the reaction above, how many grams of oxygen are involved in the reaction? Record and bubble in your answer to the nearest tenth on the answer document 18.8