Law of Conservation of Mass/Balance Equations

Physical and Chemical Changes

Review

Physical Change

• Substance changes appearance but it is still the same substance

• Water can be a solid, liquid or gas, and it is still H₂O.

Chemical Changes

• Changes to substance forms new substance with different properties

• When Iron combines with oxygen it forms the new substance of rust.

Multiple Choice

Indicate whether the photo depicts a physical change or chemical change.

• Physical change

• Chemical change

Multiple Choice

Indicate whether the photo depicts a physical change or chemical change.

• Physical change

• Chemical change

Multiple Choice

Indicate whether the photo depicts a physical change or chemical change.

• Physical change

• Chemical change

Multiple Choice

Indicate whether the photo depicts a physical change or chemical change.

• Physical change

• Chemical change

Multiple Choice

Indicate whether the video depicts a physical change or chemical change.

• Physical change

• Chemical change

Law of Conservation of Matter

• Matter cannot be created or destoyed in a chemical reaction

• What you start with, you end with. It is rearranged to form something new.

• Hydrogen gas combines with Oxygen gas to form water which is a liquid.

Chemical Equations

• •A representation of a chemical reaction using symbols of the elements

• •Quick and easy way to show a chemical reaction using symbols instead of words

• •There are 2 sides to a chemical equation – Reactants and Products

Reactants

• on the left side of the chemical equation

• the compounds that react and change

• 
  

Multiple Choice

Which are the reactants in this chemical equation?

• Na

• Na + Cl_2

• NaCL

• Cl

Multiple Choice

Which are the reactants in this chemical equation?

• Left side

• Right side

Products

• substance formed in a chemical reaction

• on the right side of the chemical reaction

Multiple Choice

Which are the products in this chemical equation?

• CH₄

• CH₄ + 2O₂

• CO₂ + 2H₂O

• 2H₂O

Multiple Choice

Which are the products in this chemical equation?

• Left side

• Right side

Balancing equations

• Count the number of atoms on the reactant side

• Count the number of atoms on product side

• Compare each element to see if they have the same amount of atoms

Multiple Choice

How many Oxygen atoms are in the reactant side in this chemical reaction?

• 4

• 6

• 1

Multiple Choice

How many atoms are represented in the reactant side in this chemical reaction?

• 8

• 9

• 10

• 11

Multiple Choice

How many atoms are represented in the product side in this chemical reaction?

• 8

• 9

• 10

• 11

Multiple Choice

Is this chemical equation balanced or unbalanced?

• balanced

• unbalanced

Evidence of Chemical Reaction

• Odor

• Light

• Precipitate

• Gas

• Color

• Temperature

• Formation of a new substance

Multiple Choice

Which is not evidence that a chemical reaction occurred in the fireworks display?

• color

• temperature

• sound

• odor

Multiple Choice

Which is the least likely evidence that a chemical reaction occurred?

• color

• sound

• light

• temperature

Density

how much mass in a given volume, and a physical property of matter.

Multiple Choice

Use the density triangle to determine the density of an object with the mass of 21.7 and volume of 3.

• 7.23 g/cm³

• 7.33 g/cm³

• 7.24 g/cm³

• 7 g/cm³

Multiple Choice

Use the density triangle to determine the density of an object with the mass of 8.14 g and volume of 3.

• 3.71 g/cm³

• 2.17 g/cm³

• 3.17 g/cm³

• 2.71 g/cm³