Chemical Reactions and Equations

A student conducts an investigation in which he mixes a white powder into a clear liquid without adding heat. The student’s observations are recorded in the image.

What is the best explanation for what the student observed?

• The white powder dissolved into the clear liquid.

• The liquid is boiling and turning into its gas form.

• The gas bubbles are a new substance that has been formed.

• The white powder and clear liquid did not chemically react.

Tags

NGSS.MS-PS1-2

How does the chemical equation shown above demonstrate the Law of Conservation of Mass?

• The number of compounds in the reactants and products are equal.

• The volume of the reactants and the volume of the products are the same.

• The masses of Hg₂Br₂, Cl₂, HgCl₂, and Br₂ are all the same.

• The number of atoms of each type of element in the reactants and products are equal.

Tags

NGSS.MS-PS1-5

Which of the following chemical equations shows that the total mass during a chemical reaction stays the same?

• 2Na + 2H₂O → NaOH + H₂

• 3Fe + 4H₂O → Fe₃O₄ + 2H₂

• 2C₂H₆ +7O₂ → 4CO₂ + 6H₂O

• 2NaOH + MgCl₂ → 2NaCl + MgOH

Tags

NGSS.MS-PS1-5

Students performed four investigations in which they combined a white solid substance with 4 different liquids. In each investigation, the students combined the solid with a liquid in a test tube and recorded observations in the table in the image.

Which investigations in the image above show evidence of a chemical reaction? Select all that apply.

• 1

• 2

• 3

• 4

Tags

NGSS.MS-PS1-2

Propane is a gas commonly used as fuel for engines and barbeques. When propane burns it combines with oxygen to produce carbon dioxide, and water. An incorrectly balanced chemical equation representing the burning of propane is shown in the image.

Why is this chemical equation unbalanced?

• The Carbon (C) in unbalanced.

• The Hydrogen (H) is unbalanced.

• The Oxygen (O) is unbalanced.

• The chemical equation is actually balanced.

Tags

NGSS.MS-PS1-5

How many atoms of Oxygen (O) are in three molecules of glucose?

• 6

• 18

• 24

• 72

Tags

NGSS.MS-PS1-1

Students conducted an investigation using steel wool and water. The students poured 100 ml of water into a beaker and then added a silver colored ball of iron to the water. Next, students observed the changes that occurred.

The students inferred that a chemical reaction occurred. What evidence best supports this inference?

• The water remained clear in color.

• The iron changed shape.

• The temperature decreased when the iron was added.

• A red solid substance formed in the water.

Tags

NGSS.MS-PS1-2

A student conducts an investigation on the reactivity of metals with a copper sulfate solution. The student places a 10 gram sample of solid aluminum into a test tube containing 15 ml of copper sulfate solution, and a 10 gram sample of solid silver into a different test tube also containing 15 ml of copper sulfate solution. Both samples of copper sulfate solution are at room temperature. The student’s observations are recorded in the table.

Which statement is supported by the student’s observations?

• A gas is produced in test tube 2.

• A chemical reaction takes place in test tube 1.

• Energy is released in test tube 2.

• The substances in both test tubes reacted chemically.

Tags

NGSS.MS-PS1-2

How many atoms of aluminum are in a molecule of magnesium aluminum oxide (Al₂MgO₄)?

• 1

• 2

• 4

Tags

NGSS.MS-PS1-1

Barium nitride is an orange-yellow solid. The equation below represents a chemical reaction that occurs when barium nitride is added to water.

How many atoms are represented in the products of this equation?

• 5

• 9

• 20

• 23

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2