Unit 3.3 Review - Chemical Formulas and Equations

How many oxygen (O) atoms are found in one molecule of Fe(OH)₂?

• 0

• 1

• 2

• 4

How many total atoms are found on the product side of the equation below?

• 1

• 2

• 3

• 9

Which of the following are NOT signs that a chemical reaction occurred?

1. precipitant

2. unexpected temperature change

3. phase change

4. unexpected color change

5. change in appearance

6. production of gas

7. odor

• 1 and 6

• 3 and 5

• 2 and 5

• all are signs of a chemical change

The reaction above shows that _____ .

• the atoms on the left are changed into different atoms on the right

• the atoms on the left form new elements

• the number of atoms on the left equal the number of atoms on the right

• the compounds on the left are produced from the atoms on the right

Which of the following statements explains what is happening in the equation above?

• CH₄ is reacting with CO₂ to form H₂O and O_2

• CH₄ is reacting with O₂ to form CO₂ and H₂O

• CO₂ and H₂O are reacting to form CH₄ and O₂

What information can you determine from looking at the chemical formula of a substance?

• the number of atoms of each element

• the state of the substance

• the color of the substance

• the number of molecules in the sample

What is the possible chemical formula for this compound?

• 3 H 1 CCl

• CCl₃H

• H₃ 1 CaCl

• CH₃Cl

If I started with 15 g of CH₄ and 3 g of O₂, what is the total mass of CO₂ and H₂O that are produced?

• 3 g

• 9 g

• 15 g

• 18 g

Which of the following is an example of a physical change?

• teeth grinding food

• saliva breaking down carbohydrates

• stomach enzymes breaking down proteins

Which of the following is an example of a chemical change?

• teeth cutting pizza into smaller pieces

• teeth grinding pizza into even smaller pieces

• saliva breaking down the crust into simple sugars