8.P.1.3 & 8.P.1.4 Review

Two different liquids are poured together in an open container. Bubbles begin to form. After the bubbling stops, it is determined that the total weight of the two liquids is less than before they were poured together. Which best describes this observation?

• Some of the atoms during the reaction escaped into the air

• Some of the atoms during the reaction were destroyed

• Some of the atoms during the reaction became heavier

• Some of the atoms during the reaction changed to a different kind of atom

This is a chemical reaction for the decomposition of carbonic acid into water and carbon dioxide.

How does the reaction support the Law of Conservation of Mass?

• Several molecules of water are produced.

• The mass of carbon atoms is reduced during the reaction

• The mass of the atoms in the reactant equals the mass of the atoms in the products.

• The mass of hydrogen atoms is the only thing that remains the same before and after the reaction.

Which statement is true about a chemical reaction?

• The physical states of the atoms in the reactants determine the products

• Some of the atoms in the reactants will be a part of the products

• The number of atoms in the reactants determines the products

• All of the atoms in the reactants will be a part of the products

Which is the best example of a chemical change?

• butter melting

• egg cooking

• paper tearing

• water evaporating

Which chemical equation best represents the Law of Conservation of Mass?

• A

• B

• C

• D

A copper wire was cut into pieces and dropped into a test tube containing acid. Bubbles formed immediately, the liquid in the test tube turned green, and the pieces of wire were no longer visible. Which most likely happened to the pieces of copper wire?

• The copper wire was chemically changed when it was cut and placed in the acid

• The copper wire was physically changed when it was cut and placed in the acid

• The copper wire was physically changed when it was cut and chemically changed when it was placed in the acid

• The copper wire was chemically changed when it was cut and physically changed when it was placed in the acid

According to the law of conservation of mass, how many hydrogen and chlorine atoms are required for this reaction?

• 1 hydrogen atom and 1 chlorine atom

• 1 hydrogen atom and 2 chlorine atoms

• 2 hydrogen atoms and 1 chlorine atom

• 2 hydrogen atoms and 2 chlorine atoms

What are the differences between chemical changes from physical changes?

• Physical changes are permanent, while chemical changes are temporary

• Chemical changes produce new substances, while physical changes do not

• Physical changes alter the properties of the substance, while chemical changes maintain the same properties

Two reactants, W and P, are combined and form a new substance with a mass of 275 g. The mass of reactant W is 200 g. What is the mass of reactant P?

• 75 g, because the mass of the reactants equals the mass of the products

• 175 g, because mass is lost after the chemical reaction

• 475 g, because the mass of the reactants equals the mass of the products

• 675 g, because mass is gained after the chemical reaction

A student lights the wick of a candle, and the candle burns for several minutes. The student makes the following observations:

-Observation 1: The wick turns black from white as it burns.

-Observation 2: The solid wax changes phases to a liquid as heat is applied to the candle.

Which choice best compares these two observations?

• Observation 1 describes a physical change, and Observation 2 describes a chemical change

• Both examples of physical change

• Observation 1 describes a chemical change, and Observation 2 describes a physical change.

• Both examples of chemical change