StemScopes Chemical Reactions Unit 2

An experiment is performed in which a crystalline substance is added to a beaker filled with room temperature water. The following observations were made:

A. The crystals dissolve

B. A precipitate is formed

C. The bottom of the beaker feels warm to touch

D. Bubbles begin to form within the water

Which observations are evidence that a chemical reaction took place?

• A

• B

• B and C

• B, C, and D

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

When vinegar and baking soda are combined, bubbles begin to form. How are the formation of bubbles evidence of a chemical reaction?

• Bubbles occur when there is a physical change.

• There was no chemical reaction because there was not a color change.

• Bubbles indicate the formation of a gas as a new product.

• You need soap to form proper bubbles.

Tags

NGSS.MS-PS1-2

Four students performed four different investigations by combining different substances. Their results are shown in the table above. In which experiment did a chemical reaction take place, and how do you know?

• In Experiment 1, a chemical reaction took place. Evidence for this is the production of bubbles, indicating a new substance was formed.

• In Experiment 2, a chemical reaction took place. Evidence for this is the amount of the solution increased, indicating more product.

• In Experiment 3, a chemical reaction took place. Evidence for this is the dissolving of the crystals, indicating the crystals took a long time to disappeared.

• In Experiment 4, a chemical reaction took place. Evidence for this is the solid remains a solid.

Tags

NGSS.MS-PS1-2

Hydrogen and oxygen react to form water. At an atomic level, how do we know that a chemical reaction has occurred?

• A. Hydrogen molecules are negative, and oxygen positive.

• B. For every oxygen atom., two hydrogen atoms are needed.

• C. The hydrogen and oxygen atoms regroup into a new molecule.

• D. Oxygen atoms are much larger than hydrogen atoms.

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2

A chemical reaction occurs that involves combining 1 atom of zinc with 2 atoms hydrogen and 2 atoms of chlorine. After the reaction, how many atoms of each element will there be?

• 1 zinc, 2 hydrogen, 2 chlorine

• 2 zinc, 2 hydrogen, 2 chlorine

• 2 zinc, 1 hydrogen, 2 chlorine

• 2 zinc, 1 hydrogen, 2 chlorine

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which of the following is the best description of the results of a chemical reaction?

• The substance seems to disappear after dissolving in water.

• The substance changes from liquid to solid at a low temperature.

• A new substance with different properties is formed.

• The reaction can be reversed to get back the original substance.

Tags

NGSS.MS-PS1-2

During a chemical reaction, substances (called reactants) are combined to form new substances (called products). Which of the following accurately describes the reactants and the products of a chemical reaction?

• The products contain a different number of atoms than the reactants but have the same properties.

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

• The products contain the same number of atoms as the reactants but have different properties.

• The number of atoms and the properties are different in the reactants and the products

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

The formula below represents the most common carbohydrate known as glucose. Which information can be determined from the chemical formula?
C₆H₁₂O₆

• The structural arrangement of the atoms in a glucose molecule
• The color of a glucose molecule
• The size of a glucose molecule
• The number of atoms of each element in a glucose molecule

Tags

NGSS.MS-PS1-1

For an investigation a student poured a blue solution of CuSO₄ into a beaker. The student placed a shiny, silver-colored strip of zinc metal in the solution and observed the changes.
The student inferred that a chemical reaction occurred. What evidence supports this inference?

• A dark solid formed on the zinc metal.
• 
  The zinc metal remained silver-colored and shiny
• The CuSO₄ solution turned blue when the zinc metal was added.
• None of these

Tags

NGSS.MS-PS1-2

Which of the following equations demonstrates an actual chemical reaction that forms a new substance?

• A
• B
• C
• D

Tags

NGSS.MS-PS1-2