4-5. 2Cu + O 2 2CuO 2Na + Cl 2 2NaCl. sodium + chlorine = sodium + chlorine. copper + oxygen = copper + oxygen

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1 Skill Development/Guided Practice 1 Name The Law of Conservation of Matter states that in a chemical reaction the number of atoms is conserved no matter how they are arranged. 1. Two copper (Cu) molecules reacted with one molecule of oxygen (O 2 ) to yield two molecules of copper oxide. 2. Two molecules of sodium (Na) reacted with one molecule of chlorine (Cl 2 ) to form two molecules of sodium chloride (NaCl). 2Cu + O 2 2CuO 2Na + Cl 2 2NaCl copper + oxygen = copper + oxygen 3. One molecule of methane (CH 4 ) reacted with two molecules of oxygen (O 2 ) to produce one molecule of carbon dioxide (CO 2 ) and two molecules of water (H 2 O). sodium + chlorine = sodium + chlorine 4. Two molecules of iron (Fe) reacted with three molecules of chlorine (Cl 2 ) to form two molecules of iron trichloride (FeCl 3 ). CH 4 + 2O 2 CO 2 + 2H 2 O 2Fe + 3Cl 2 2FeCl 3 carbon + hydrogen + oxygen = carbon + hydrogen + oxygen iron + chlorine = iron + chlorine 4-5

2 Skill Development/Guided Practice (continued) The Law of Conservation of Matter states that in a chemical reaction the number of atoms is conserved no matter how they are arranged. Research #1: The Law of Conservation of Matter Chemistry is cool, but it is not magic. According to the law of conservation of matter, matter can neither be created nor destroyed. Essentially, this means that atoms themselves cannot be created or destroyed. In a chemical reaction, whatever atoms are present at the beginning of a reaction, must also be present in the products of the reaction. The only difference between the reactants and products, then, is the arrangement of the chemical bonds between atoms, not the atoms themselves. Below is the chemical equation for the reaction that forms rust. 4Fe + 3O 2 > 2Fe 2 O 3 In the reaction, there are four iron (Fe) atoms on the reactant side and four on the product side. There are six oxygen (O) atoms on the reactant side and six on the product side. Research #2: The Law of Conservation of Matter The Law of Conservation of Matter states that matter can neither be created or destroyed, but can be changed in form. To understand this law, you can think in terms of the atoms themselves. Take the reaction between hydrogen and oxygen. The product of this reaction is water. The unbalanced chemical equation for this reaction is H 2 + O 2 > H 2 O If you count up the number of hydrogen atoms on each side, then you find that each side has two hydrogen atoms each. Now count up the oxygen atoms on each side of the chemical equation. The left side of the equation has two oxygen atoms and the right side has only one. This unbalanced chemical equation does not obey the Law of Conservation of Matter. Now let's look at the balanced equation. 2H 2 + O 2 > 2H 2 O. If you recount the number of atoms on each side for each substance, then you have four atoms of hydrogen (H) and four atoms of oxygen. Here both sides are equal. This balanced equation obeys the Law of Conservation of Matter. Description Research #1 Research #2 Both 1. Gives examples of balanced chemical equations. 2. Gives example of an unbalanced chemical equation. Why do the balanced chemical equations prove the Law of Conservation of Matter? Why does the unbalanced chemical equation not obey the Law of Conservation of Matter? Write a definition for the Law of Conservation of Matter. Use your own words. 6-9

3 Skill Development/Guided Practice (continued) The Law of Conservation of Matter states that in a chemical reaction the number of atoms is conserved no matter how they are arranged. Ag + S Ag 2 S 4Fe + 3O 2 2Fe 2 O Ca(OH) 2 + 2HCl CaCl 2 + 2H 2 O C 6 H 12 O 6 2C 2 H 5 OH + CO

4 Name Independent Practice The Law of Conservation of Matter states that in a chemical reaction the number of atoms is conserved no matter how they are arranged. Laboratory What happens when baking soda is mixed with vinegar? Baking Soda + Vinegar =??? Baking soda is a fabulous ingredient to clean with. Pots and pans scrubbed clean in an instant. Bathtubs shine. Vinegar is also a stellar cleaning tool. Countertops are clean and disinfected, and glasses are rinsed sparkly clean. You d think, putting these two hard-hitting ingredients together would leave you with something no man-made cleaner could touch, right? What childhood would be complete without the baking soda and vinegar volcano science project? Remember how it exploded up into a creamy, bubbly, overflowing blob? Well, what happened is that a chemical reaction took place. The vinegar or acetic acid reacts with sodium bicarbonate (baking soda). The bubbles you see from the reaction come from the carbon dioxide. What s left is a dilute solution of sodium acetate in water. In fact, it s almost all water. That s not going to get your counters very clean. C 2 H 4 O 2 + NaHCO 3 NaC 2 H 3 O 2 + H 2 O + CO 2 acetic acid baking soda sodium acetate water carbon dioxide 13

5 Access Concepts and Experimentation When a match is lit, sulfur (S) reacts with oxygen (O 2 ) in the air to release energy and form sulfur dioxide (SO 2 ). Which is a true statement about this chemical reaction? S + O 2 SO 2 a. two molecules of oxygen react with one molecule of sulfur Answer Justify your answer b. two molecules of sulfur oxide are produced c. the molecules in the reactants and the products contain the same number of atoms of sulfur and oxygen d. the molecules in the reactants and the products contain different numbers of atoms of sulfur and oxygen 14

6 Access Concepts and Experimentation Determine which chemical reactions obey the Law of Conservation of Matter. Justify your answer. Description Obeys the Law of Conservation of Matter Does not obey the Law of Conservation of Matter Justify your answer. Four molecules of sodium (Na) react with one molecule of oxygen (O 2 ) to produce one molecule of sodium oxide (Na 2 O). 4Na + O 2 > 2 Na 2 O One molecule of carbon (C) is added to one molecule of hydrogen (H 2 ) to produce one molecule of methane (CH 4 ) and one molecule of chlorine (Cl 2 ). C + H 2 > CH 4 + Cl 2 One molecule of nitrogen (N 2 ) reacts with three molecules of hydrogen (H 2 ) to produce one molecule of ammonia (NH 3 ). N 2 + 3H 2 > NH 3 Two molecules of aluminum oxide (Al 2 O 3 ) produce four molecules of aluminum (Al ) and three molecules of oxygen (O 2 ). 2 Al 2 O 3 > 4Al + 3O 2 Acetylene gas is mixed with air at the burner and combusts producing a bright white flame. The products of the reaction are carbon dioxide and water vapor. 2 C 2 H O 2 > 4 CO 2 + 2H 2 O 15

7 Access Concepts and Experimentation Have you ever prepared meat on a propane grill? The meat placed over the burner is cooked with the help of heat energy released after the burning of propane gas (C 3 H 8 ). When propane is burned with the help of oxygen (O 2 ), it gives off heat energy, water (H 2 O), and carbon dioxide (CO 2 ). C 3 H 8 + 5O 2 3CO 2 + 4H 2 O a. The oxygen in the reactants rearranges to produce only water. Answer Justify your answer b. The reaction produces five molecules of oxygen and four molecules of water. c. All the molecules in the reactants and the products contain oxygen. d. The atoms in propane and oxygen rearrange to produce carbon dioxide and water. 16

8 Whiteboard Insert Ac - Actinium Ag - Silver Al - Aluminum Am - Americium Ar - Argon As - Arsenic At - Astatine Au - Gold B - Boron Ba - Barium Be - Beryllium Bh - Bohrium Bi - Bismuth Bk - Berkelium Br - Bromine C - Carbon Ca - Calcium Cd - Cadmium Ce - Cerium Cf - Californium Cl - Chlorine Cm - Curium Cn - Copernicium Co - Cobalt Cr - Chromium Cs - Cesium Cu - Copper Db - Dubnium Ds - Darmstadtium Dy - Dysprosium Er - Erbium Es - Einsteinium Eu - Europium F - Fluorine Fe - Iron Fl - Flerovium Fm - Fermium Fr - Francium Ga - Gallium Gd - Gadolinium Ge - Germanium H - Hydrogen He - Helium Hf - Hafnium Hg - Mercury Ho - Holmium Hs - Hassium I - Iodine In - Indium Ir - Iridium K - Potassium Kr - Krypton La - Lanthanum Li - Lithium Lr - Lawrencium Lu - Lutetium Lv - Livermorium Md - Mendelevium Mg - Magnesium Mn - Manganese Mo - Molybdenum Mt - Meitnerium N - Nitrogen Na - Sodium Nb - Niobium Nd - Neodymium Ne - Neon Ni - Nickel No - Nobelium Np - Neptunium O - Oxygen Os - Osmium P - Phosphorus Pa - Protactinium Pb - Lead Pd - Palladium Pm - Promethium Po - Polonium Pr - Praseodymium Pt - Platinum Pu - Plutonium Ra - Radium Rb - Rubidium Re - Rhenium Rf - Rutherfordium Rg - Roentgenium Rh - Rhodium Rn - Radon Ru - Ruthenium S - Sulfur Sb - Antimony Sc - Scandium Se - Selenium Sg - Seaborgium Si - Silicon Sm - Samarium Sn - Tin Sr - Strontium Ta - Tantalum Tb - Terbium Tc - Technetium Te - Tellurium Th - Thorium Ti - Titanium Tl - Thallium Tm - Thulium U - Uranium Uuo - Ununoctium Uup - Ununpentium Uus - Ununseptium Uut - Ununtrium V - Vanadium W - Tungsten Xe - Xenon Y - Yttrium Yb - Ytterbium Zn - Zinc Zr - Zirconium 17