Law of Conservation of Matter

Law of Conservation of Matter Test Review What have you learned this past week?

Which of the following states the Law of Conservation of Matter? • a.Two compounds combine to form a new • compound with different properties. • b. When atoms are recombined in a chemical • reaction, some matter may be destroyed. • c. Matter cannot be created or destroyed in • a chemical reaction.

During chemical reactions, matter is neither created nor destroyed, the atoms are just rearranged. Reactants Products How many carbons (black) in the reactants? products? How many hydrogens (white)? in reactants? products? How many oxygens (red)? in reactants? products?

The Reactants combine and react to yield new Products ReactantsProducts NaHCO3 + CH3COOH → CO2 + H2O + CH3COONa (baking soda) (vinegar) (carbon dioxide) (water) (sodium acetate) • What do you notice about the number of atoms in each column? ________________

The Reactants combine and react to yield new Products ReactantsProducts NaHCO3 + CH3COOH → CO2 + H2O + CH3COONa (baking soda) (vinegar) (carbon dioxide) (water) (sodium acetate) 3 3 5 5 5 5 1 1 14 14 • What do you notice about the number of atoms in each column? They are the equal

Which are the reactants in the following chemical equation? Fe2O3 Fe2 O3 Fe2 and O3 Fe2 + O3 Fe2O3

Which are the products in the following chemical equation? Fe2O3 Fe2 O3 Fe2 and O3 Fe2 + O3 Fe2O3

According to this equation, what happened to the iron and oxygen? (Read carefully and think!) They combined chemically to form the elements iron and oxygen. b. They combined physically to form a mixture. They combined chemically to form a compound. d. They combined physically to form an element. Fe2 + O3 Fe2O3

According to the Law of Conservation of Mass, which statement is true? • Matter cannot change form. • b. The total mass of the reactants equals the • total mass of the products. • The total mass of the reactants is greater • than the total mass of the products. • The total mass of the reactants is less • than the total mass of the products.

If the reactants in a chemical reaction contain 6 oxygen atoms and 3 nitrogen atoms, what must be true of the products? • The products must contain 6 oxygen atoms • and 3 nitrogen atoms • b. The product must be a molecule made of • 9 atoms. • The product must contain 3 oxygen atoms • and 6 nitrogen atoms • d. The products must be glucose

If the reactants in a chemical reaction contain 6 oxygen atoms and 3 nitrogen atoms, what must be true of the products? • The products must contain 6 oxygen atoms • and 3 nitrogen atoms • b. The product must be a molecule made of • 9 atoms. (No! They can be in different molecules) • The product must contain 4 oxygen atoms • and 6 nitrogen atoms (They don’t swap!) • d. The products must be glucose

(#2 from Coach book p.107) The reactants involved in a chemical reaction are shown. How many O atoms must be present in the product that forms from this reaction? Na2O + H2O ? a. 1 b. 2 c. 3 d. 4

(#2 from Coach book p.107) The reactants involved in a chemical reaction are shown. How many Na atoms must be present in the product that forms from this reaction? Na2O + H2O ? a. 1 b. 2 c. 3 d. 4

During the chemical reaction shown below, methane (CH4) and oxygen (O2) combine to produce carbon dioxide (CO2) and water (H2O). The balanced chemical equation identifies the reactants and products for this reaction along with some of their masses. What mass (in grams) of oxygen (O2) is required for this reaction to occur? methaneoxygencarbon dioxidewater CH4 + O22CO2 + H2O 16g?44g36g a. 16 b. 36 c. 44 d. 64

What mass (in grams) of oxygen (O2) is required for this reaction to occur? methaneoxygencarbon dioxidewater CH4 + O22CO2 + H2O 16g?44g36g Think: 16 + X = 44 + 36 16 + X = 80 -16 -16 X = 64 a. 16 b. 36 c. 44 d. 64

The picture to the right shows the reactants from a chemical reaction. Which of the following pictures could represent the products of this reaction? a. b. c.

Now, turn to a neighbor and explain one thing you have learned about the law of conservation of matter regarding the number of atoms in the reactants and products AND 2. the mass of the reactants and the products.

Law of Conservation of Matter