WRITING CHEMICAL FORMULAS FOR THE REACTANTS AND …



Lab - Writing Chemical Equations

PRE-LAB

1. What do the following physical state symbols mean when they are written behind chemical formulas?

(s) (g)

(l) (aq)

2. What is the role of the catalyst in a chemical reaction?

3. What is a precipitate?

4. What does the term diatomic mean?

5. List the seven elements that are diatomic in the elemental state?

PROCEDURE:

Reaction #1: Pour 3.0 mL of hydrogen peroxide into a clean test tube. Add a very small amount of manganese (IV) oxide to the hydrogen peroxide in the test tube. The manganese (IV) oxide is called a catalyst. Test the gas bubbles given off during the reaction with a glowing wooden splint. The splint should relight. This a positive test for the gas oxygen. The colorless liquid that is formed is water.

1. Write the correct chemical formulas for the reactant and products of reaction #1.

Write a physical state symbol behind each formula. Balance the equation.

Hydrogen peroxide ( water + oxygen

______________ ( ) ( _________ ( ) + _____________ ( )

2. What is the reactant in reaction #1?

3. Classify Reaction #1

Reaction #2: Pour 3.0 mL of hydrochloric acid into a clean test tube. Add a small piece of magnesium metal to the test tube. Test the gas given off during the reaction with a lighted or flaming splint. The gas should explode. This is a positive test for hydrogen gas. The colorless solution is magnesium chloride.

4. Write the correct chemical formulas for the reactants and products of reaction #2.

Write the physical state symbol behind each formula. Balance the equation.

Magnesium + hydrochloric acid ( magnesium chloride + hydrogen

___________ ( ) + __________ ( ) ( __________ ( ) + ___________ ( )

5. What are the reactants in reaction # 2?

6. Classify Reaction #2

Reaction #3: Pour 3.0 mL of a sodium chloride solution into a clean test tube. Add 6 drops of silver nitrate solution into the test tube. Stopper and shake the contents of the test tube. A precipitate (an insoluble solid formed during a chemical reaction) should appear suspended in a colorless solution. The precipitate is silver chloride and the colorless solution is sodium nitrate. What color is the precipitate? _______________

7. Write the correct chemical formulas for the reactants and products of reaction #3.

Write a physical state symbol behind each formula. Balance the equation.

Sodium chloride + silver nitrate ( silver chloride + sodium nitrate

__________ ( ) + ____________ ( ) ( __________ ( ) + ____________ ( )

8. What are the products in the reaction # 3?

9. Classify Reaction #3

Reaction #4: Pour 3.0 mL of acetic acid solution into a clean test tube. Add a small scoop of sodium bicarbonate to the acid in the test tube. A colorless gas is formed, as well as a colorless solution. The colorless solution is sodium acetate and liquid water. Test the gas given off during the reaction with a lighted or flaming splint. The flame should go out. This is a positive test for carbon dioxide gas.

10. Write the correct chemical formulas for the reactants and products of reaction #4.

Write a physical state symbol behind each formula. Balance the equation.

acetic acid + sodium bicarbonate ( sodium acetate + water + carbon dioxide

_________ ( ) + _________ ( ) ( ________ ( ) + ________ ( ) + _________ ( )

11. Classify Reaction #4

Reaction #5: Pour 3.0 mL of sodium iodide solution into a clean test tube. Add 5 drops of lead (II) nitrate to the test tube. Stopper and shake the contents of the test tube. A precipitate should appear suspended in a colorless solution. The precipitate is lead (II) iodide and the colorless solution is sodium nitrate. What color is the precipitate? ____________

12. Write the correct chemical formula for the reactants and products of reaction #5.

Write a physical state symbol behind each formula. Balance the equation.

Lead (II) nitrate + sodium iodide ( lead (II) iodide + sodium nitrate

__________ ( ) + __________ ( ) ( __________ ( ) + ___________ ( )

13. Classify Reaction #5

Reaction #6: Use tweezers to insert a small piece of magnesium into a flame. Do not look directly at the light. Use cobalt glass to protect your eyes. The solid magnesium reacts with oxygen in the air to produce a solid white magnesium oxide.

14. Write the correct chemical formulas for the reactant and products of reaction #6.

Write a physical state symbol behind each formula. Balance the equation.

Magnesium + oxygen ( magnesium oxide

______________ ( ) + ____________ ( ) ( _____________ ( )

15. What is the evidence a reaction occurred?

16. Classify Reaction #6

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