BALANCING CHEMICAL EQUATIONS

1. BALANCING CHEMICAL EQUATIONS Refresh your skills with some of the websites listed earlier.

2. Do you remember your experiment with baking soda (NaHCO3) and vinegar (CH3COOH)? It is written below in case you do not remember. EXPERIMENT A It would be useful to have another person with you to watch the thermometer while you test the chemical reaction with the match, or you could repeat the experiment twice. Take an unlit match and using tape, attach it to something longer like a Popsicle stick, eating utensil, writing utensil, etc. (A long match stick would be perfect.) This will make it easier to place the match closer to the chemical reaction without burning your fingers. Place a cup in a sink. Place a teaspoon of baking soda in the cup with a thermometer. Pour a small amount of vinegar in the cup. Light a match and hold it near the surface of the vinegar where the chemical reaction is occurring. Correct fire safety procedure should be used at all times. After your chemical reaction is finished, dispose of the baking soda and vinegar solution down the sink.

3. Question #1 Write the chemical equation for combining baking soda (NaHCO3) and vinegar (CH3COOH). There are three products in this chemical reaction. Two of the products are water and sodium acetate (CH3COO-Na+). The other product is the gas (either O2 or CO2) that you discovered from your match test. If the equation needs balancing, balance it.

4. Written below is the experiment you performed with Alka Seltzer was dissolved in water. EXPERIMENT B  It would be useful to have another person watch your thermometer in this experiment as well. In a glass cup, place a tablet of Alkaseltzer or Efferdent. Tape another match on something that will extend its length. Place your thermometer in the cup. Pour the cup half full of water. As the chemical reaction occurs, light your match and stick it down into the foaming area. The byproducts of this reaction can also be disposed of down the sink.

5. Question #2 Write a chemical equation for the reaction that occurs when Alka Seltzer is dissolved in water. Alka Seltzer is a solid mixture of two substances, sodium bicarbonate (NaHCO3) and citric acid (H3C6H5O7). When dissolved in water, these two reactants react to form water, carbon dioxide, and an ionic compound (chemical formula Na3C6H5O7). Remember to balance this equation.

6. CATALYSTS **A catalyst is a substance that increases a reaction rate without being used up in the reaction. **Yeast contains an enzyme (a catalyst for biological reactions) that will speed up the process of hydrogen peroxide (H2O2) turning into water and oxygen. **Because the catalyst in a chemical reaction is not used up or changed it does not appear on either the reactant or product side. It can be placed over the arrow to show that it was present in the chemical reaction

7. Remember the yeast and hydrogen peroxide experiment? It is written below. EXPERIMENT C This is another experiment where it would be useful to have another person watch the thermometer while you light the match. In a glass cup, place a tablespoon of yeast. Place the thermometer in the glass as well. Again, tape an unlit match on something to make it longer. Pour in a small amount of hydrogen peroxide. As the chemical reaction foams, stick the match into the foam. The byproducts of this chemical reaction can also be poured down the sink.

8. Question #3 • Write the chemical equation that describes hydrogen peroxide (H2O2) decomposing into water and a gas. You obviously know which gas was used by your match test and by looking at the chemical formula of hydrogen peroxide. You can write the word yeast above the arrow to signify that it helped make the reaction occur faster. Remember to balance your equation.

9. The chemical reaction of photosynthesis • Photosynthesis is basically the process where plants take in carbon dioxide, water, and sunlight to produce glucose (a simple carbohydrate) and oxygen.

10. Question #4 • Write a basic chemical equation for photosynthesis. The reactants are carbon dioxide, water, and sunlight. The products are glucose (C6H12O6) and oxygen (O2). The word sunlight can be written on the reactant side. Remember to balance your equation.

11. The chemical reaction of aerobic respiration • Aerobic respiration is the process where animals (including ourselves) take in glucose and oxygen. The products of aerobic respiration are energy, carbon dioxide and a relatively small amount of water.

12. Question #5 • Write the basic chemical equation for aerobic respiration. The reactants are glucose (C6H12O6) and oxygen (O2). The products are energy, carbon dioxide, and water. You can just write the word energy on the product side of the equation. Remember to balance the equation.

13. Question #6 How are the chemical reactions for photosynthesis and aerobic respiration similar? How are they different? Why is this nice for you?

14. Different Types of Chemical Reactions There are four main types of chemical reactions: Combustion, Decomposition, Single-Replacement, and Double-Replacement

15. Combination Reactions • Chemical reactions where a single product is produced from two (or more) reactants. • Example: X + Y → XY

16. Decomposition Reactions • Chemical reactions where a single reactant is converted into two (or more) simpler substances (elements or compounds). • Example: XY → X + Y

17. Single-Replacement Reactions • Chemical reactions where an atom or molecule replaces an atom or group of atoms from a compound. • X + YZ → Y + XZ

18. Double-Replacement Reactions • Chemical reactions where two substances exchange parts with one another and form two different substances. • Example: AX + BY → AY + BX

19. Question #7—Balance the following equation • Zn + HCl → ZnCl2 + H2 • Is this chemical reaction an example of a decomposition, combination, single-replacement, or double-replacement chemical reaction?

20. Question #8—Balance the equation. • KClO3→ KCl + O2 • Is this chemical reaction an example of a decomposition, combination, single-replacement, or double-replacement chemical reaction?

21. Question #9--Balance the following equation S8 + F2 → SF6 • Is this chemical reaction an example of a decomposition, combination, single-replacement, or double-replacement chemical reaction?

22. Question # 10 Balance the following equation C2H6 + O2 → CO2 + H2O • Is this chemical reaction an example of a decomposition, combination, single-replacement, or double-replacement chemical reaction?

23. Question #11 Ammonium hydroxide is added to iron acetate. The products are a green blob (iron hydroxide) and a liquid (ammonium acetate.) • Is this chemical reaction an example of a decomposition, combination, single-replacement, or double-replacement chemical reaction?