***Topic 2 Review: Chemical Reactions***

After reading about the kinds of mixtures and their characteristics, Jasmine wants to know how a heterogeneous mixture is different from a homogeneous mixture. What is the main difference between these two kinds of mixtures?

• n a heterogeneous mixture, the components are not evenly spread throughout the mixture. In a homogeneous mixture, the components are evenly spread throughout the mixture.

• In a homogeneous mixture, the components are not evenly spread throughout the mixture. In a heterogeneous mixture, the components are evenly spread throughout the mixture.

After reading that a solution is a homogeneous mixture, Jasmine wondered about her favorite morning drink, grape juice. Which statement about the solution that makes up grape juice is true?

• Sugar is the solvent, and water is one of the solutes.

• Water is the solvent, and sugar is one of the solutes.

Julia has been studying the best ways to separate different kinds of mixtures. After learning about how mixtures are classified, Julia saw a picture and immediately knew how it was classified. Look at the image. Then, circle the words that complete the sentence below to identify the kind of mixture shown and the best way to separate it.

This mixture is classified as a(n) (colloid / suspension / filter / evaporation), and the best way to separate it is by (evaporating / colloiding / suspending / filtering) it.

• suspension, filtering

• colloid, suspending

Later that day, Will made toast and buttered it, but then he left the butter out on the warm stove. What kind of change would most likely take place with the butter?

• Chemical

• Physical

Tags

NGSS.MS-PS1-4

Macy has been studying physical and chemical reactions in school. She read about chemical reactions and how energy is either required or released during chemical reactions. Which word describes the direction of heat flow illustrated in the picture?

• Chemical

• Endothermic

• Exothermic

Tags

NGSS.MS-PS3-3

NGSS.MS-PS3-4

Choose the words that correctly complete the sentences.

After having studied chemical reactions in school, Jose knew that when oxygen and hydrogen gases combine in the correct amounts, the combination yields a new substance, water. The hydrogen and oxygen are (products / reactants / synthetics / polymers) while the water is the (product / reactant / synthetic / polymer).

• products, reactant

• reactants, synthetic

• reactants, product

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Alex saw a rusty old car in an abandoned lot. Because he had recently read about chemical reactions, he began to wonder how the rust formed. What happened to cause the rust on the steel car?

• A physical change took place in the steel of the car to form rust.

• Oxygen in the air reacted with the paint on the car and formed rust.

• Oxygen in the air chemically combined with the iron in the steel to form rust.

Tags

NGSS.MS-PS1-1

After learning about the law of conservation of mass, Remy began to wonder about how to best test this law. She wanted to show that the amounts of matter did not change but produced an equal amount of a different kind of matter. What is the best way to study this law?

• in a homogeneous mixture

• in a heterogeneous mixture

• in a closed system

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Choose the words that correctly complete the sentence below.

After learning about the law of conservation of mass, Sammy became interested in balancing equations. He knew that the symbol for aluminum was Al and silver tarnish was Ag2S. He also knew that mixing the two chemicals yielded pure silver, or Ag, in an aluminum sulfide solution. Here is the equation showing this reaction:

3 Ag2S + 2 Al → 6 Ag + Al2S3

This equation is (synthesis / unbalanced / replacement / balanced), and it represents a(n) (unbalanced / balanced / synthesized / replaced) chemical reaction.

• synthesis; balanced

• balanced; replacement

Tags

NGSS.MS-PS1-5

Calvin was using super glue one afternoon after learning about synthetic materials. He understood that chemists create different kinds of new products based on their knowledge of the properties of substances and how they react with each other. What kind of product is super glue?

• accidental

• developed

Tags

NGSS.MS-PS1-3