Chemical Equations and Reactions LESSON

Chemical Equations and Reactions:

Test Review (LESSON)

By Julie Edwards

​Let's review counting atoms!

​Watch the video

​

​When the instructor says "ions" he is refering to the atoms.

When he says "moles" he is refering to the molecules.​

​Watch the video

Practice Time!

Multiple Choice

Strontium phosphate, Sr₃(PO₄)₂ is a crystalline substance used in medicine and industry. How many phosphorus atoms are represented in the formula for Sr₃(PO₄)_2.

• 2

• 3

• 4

• 8

Multiple Choice

The table shows the chemical formulas for four substances.

Which substances have the same number of carbon atoms?

• Substances 1 and 2

• Substances 2, 3, and 4

• Substances 2 and 3 only

• Substances 1 and 3

Multiple Choice

The formula for glucose is C₆H₁₂O₆. How many elements does glucose contain?

• 1

• 3

• 24

• 432

Multiple Choice

The formula for glucose is 6C₆H₁₂O₆. How many molecules of glucose does this formula show?

• 1

• 6

• 12

• 36

Multiple Choice

Which of the following is correct?

• reactants ← products

• reactants products

• reactants → products

• reactants = products

Multiple Choice

In the chemical equation, the large numbers in front of 12O₂ represent —

• numbers divisible by the subscript

• the amount of energy in that substance

• the number atoms of each element in the molecule

• the number of molecules of that substance in the reaction

Poll

How is it going so far?

• Great! I got this.

• ok, I get some of it but some of it is hard.

• I feel lost.

Open Ended

What questions do you have for me so far?

More information!

Watch the next couple of videos.​

​Practice time again!

Multiple Choice

During an investigation, a student combined the two clear, colorless solutions shown below.

The student observed that the temperature changed from 25°C to 23°C when the solutions were combined and that a white substance rapidly formed and settled to the bottom of the container. What most likely happened to produce these results?

• One of the original compounds came out of solution.

• The solutions reacted chemically.

• Some of the water froze into ice crystals.

• Rapid evaporation of water occurred, leaving a solid.

Multiple Choice

A student added yeast and sugar to lukewarm water and placed it in a flask. She stretched a balloon over the opening of the flask. After several minutes, she noticed small bubbles rising along the side of the flask as the balloon slowly began to inflate. The student concluded that —

• A physical change was occurring.

• The water, sugar, and yeast were products of a chemical reaction.

• The bubbles indicated a chemical change.

• The strong smell was evidence of a physical change.

Multiple Choice

All of the arrows indicate —

• chemical changes

• irreversible changes

• physical changes

• continuous change

Multiple Choice

Which statement best describes evidence that a chemical reaction occurs as bread bakes?

• The water in the bread dough evaporates.

• The bread rises as gas bubbles form in the baking bread.

• The bread takes the shape of the container in which it is baked.

• The water in the bread dough is used to keep the bread moist as it bakes.

Multiple Choice

A precipitate is

• Rain

• Snow

• A solid formed in a chemical reaction

• Condensation formed in a chemical reaction

Multiple Choice

A chemical change is different than a physical change because in a chemical change

• Chemicals are used
• Molecules do not physically touch
• A new substance is formed and in a physical change no new substance is formed
• The change can be seen but in a physical change it cannot

Poll

How is it going so far?

• Great! I got this.

• ok, I get some of it but some of it is hard.

• I feel lost.

Open Ended

What questions do you have for me so far?

​Is it balanced or not?

​Practice time again!

Multiple Choice

Balanced or Unbalanced?

CH₄ + 2O₂ ---> CO₂ + 2H₂O

• Balanced

• Unbalanced

Multiple Choice

Balanced or Unbalanced?

NaBr + CaF₂ -----> NaF + CaBr₂

• Balanced

• Unbalanced

Multiple Choice

Balanced or Unbalanced?

NaBr₂ + CaF -----> NaF + CaBr₂

• Balanced

• Unbalanced

Multiple Choice

The arrow in a chemical equation represents the ...

• subscript

• coefficient

• chemical reaction

• phase change

Multiple Choice

Which is not true about the law of conservation of mass?

• Nothing is created

• The same number of atoms are in both the products and reactants

• New atoms are created when a new substance is formed

• Nothing is destroyed

Multiple Choice

Is this equation balanced?  (Are there the same amount of H and O atoms on both sides of the equation?)    $$H_2O_2\rightarrow\ H_2O\ +\ O_2$$  

• Yes

• No