Evidences of Chemical Reactions

Evidence of A Chemical Reaction

*Using the C P R method*

What is this?

• Claim: This is where you look at each answer choice and determine (in your opinion), the best answer choice.

• Proof: Now that you decided on your answer PROVE IT. Check for key words in the question that LED you to the claim.

• Reasoning: In one sentence, explain HOW the evidence SUPPORTS your claim (answer choice).

How Do I Apply It?

• C: A chemical reaction has occurred to form a new substance with different properties.

• E: Precipitation, clogged, oxidize

• Because precipitation clogs and oxidizes in our pipes, a chemical reaction has occurred to form a new substance with different properties.

Evidences of A Chemical Reaction

• Don't forget to look for these evidences when reading the question

Multiple Choice

When two colorless liquids are mixed, a red precipitate forms.

Which statement below is FALSE?

• New chemical bonds were formed with different properties.

• A color change and precipitate forming is evidence a chemical reaction has occurred.

• A precipitate forming is NOT evidence of a chemical reaction.

Multiple Select

Identify ALL evidences of a chemical reaction.

• Change of state (liquid to gas)

• Color change

• Temperature change

• Tearing a paper

• Burning a paper

Multiple Choice

Which statement below describes a PHYSICAL change?

• Burning the crust of the bread when making toast.

• Placing waffles in the toaster and applying butter on it.

• Frying an egg to make an egg sandwich.

• Using a cookie cutter to make heart-shaped cookies.

Multiple Select

When a chemical change occurs, ____________ with ___________ is formed.

• a new substance

• different properties

• the same substance

• same properties

Multiple Choice

Which statement below is NOT evidence that a chemical reaction has occurred during the photosynthesis equation?

• Glucose and Oxygen is a precipitate reaction.

• The formation of Glucose and Oxygen gas is released to form a new substance.

• Sunlight (light) acting as a booster to help speed up the process of Glucose.

Multiple Choice

When a student mixes baking soda and vinegar, she notices that gas and bubbles are formed after.

Which statement below PROVES that a chemical reaction has taken place.

• The baking soda evaporates into the air when mixed with vinegar.

• Baking soda chemically changes once the student adds it to vinegar.

• The baking soda condenses into the air when mixed with vinegar.

• The atoms of baking soda and vinegar were destroyed after adding it to vinegar.

Multiple Select

Select all the statements below that show evidence of a chemical change.

• Food that changes shape once you chew it in your mouth.

• A partially eaten apple that is left out and turns brown.

• Heating up sugar in a pan turning from white to brown to make caramel.

• A pile of ashes that form from burning paper.