STAAR Review: Chemical Reactions and Density

A student observes some sugar as it is heated and burns. The student concludes that a chemical reaction has occurred. Which of the following observations about the burning sugar provides evidence of a chemical reaction? (8.5E)

• Heat is added to the sugar crystals.

• The sugar melts and becomes a liquid.

• The temperature of the sugar increases.

• Gas is produced as the sugar turns black.

Tags

NGSS.MS-PS1-2

Which of the following could be the chemical formula for sulfuric acid (shown in the picture)? (8.5D)

• HSO

• HSO₄

• H₂SO₄

• HS₂O₄

Tags

NGSS.MS-PS1-1

On the following equation, how many total Hydrogen atoms are on the product side? -- (8.5F)

• 3

• 11

• 4

• 8

Tags

NGSS.MS-PS1-1

Based on the reaction shown, which statement best SUPPORTS the Law of Conservation of Mass? (8.5F)

Zn + 2HCl -----> ZnCl₂ + H₂

• There are more chlorine atoms in the reactant.

• There are more hydrogen atoms in the product.

• The number of chlorine atoms is unequal in the reactants and products.

• The number of reactant atoms is equal to the number of product atoms.

Tags

NGSS.MS-PS1-5

How many elements are found in 2H₂SO₄? (6.5C)

• 2

• 3

• 4

• 5

Tags

NGSS.MS-PS1-1

Which two compounds contain the same total number of atoms? (8.5D)

• a

• b

• c

• d

Tags

NGSS.MS-PS1-1

When you chew, the particles of food are broken down before they are swallowed. How would you describe this kind of change? (8.5E & 7.6B)

• A physical change because swallowing is a physical motion

• Both a physical and chemical change because food starts being digested before it is swallowed

• A chemical change because the particles of food get mixed together

• A physical change because the particles of food are getting smaller

Chemicals on the left of an equation that react are called -- (8.5F)

• reactants

• products

• coefficients

• subscripts

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Chemicals on the right of an equation that are produced are called -- (8.5F)

• reactants

• products

• coefficients

• subscripts

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

A rectangular block of copper metal weighs 1890 g. The dimensions of the block are 8 cm x 5 cm x 5 cm. From this data, what is the density of copper? (6.6B)

• 9.45 g/cm³

• 1,690 g/cm³

• 2,090 g/cm³

• 0.106 g/cm³