Physical vs. Chemical Changes Warm-up 2 May 2015 From the “Cooking with Chemistry” activity, describe how did you use phase change to complete the final.

Physical vs. Chemical Changes

Warm-upApril 21, 2023

From the “Cooking with Chemistry” activity, describe how did you use phase change to complete the final task of separating the salt from the solution?

http://whatscookingamerica.net/Foto4/BoilingWater.bmp

StandardApril 21, 2023

5.a. I know reactant atoms and molecules interact to form products with different chemical properties.

Physical Property: Chemical Property:  

Example: Example:   

Physical Change: 

Chemical Change:

Example: 

Example: 

Signs of a physical change:

Signs of a chemical change:

What’s the Difference?

Matter can change Examples: Freeze, cut, burn, etc. 2 types of changes

1. Physical changes

2. Chemical changes

Physical Property

Characteristic of matter that does not change the substance (using senses)

Physical Changes

Matter changes form WITHOUT becoming something new– You start and end with same thing (see below)

Examples: cutting, freezing, melting, etc.

Molecules in Physical Changes

Chemical Property

Describes matter on its ability to change into new matter– Flammability: ability of substance

to burn– Reactivity: ability of substance to

change into new substance

Chemical Changes

Matter changes, becomes NEW substance– Start and end with different things

Usually irreversible (can’t change back) Examples: burning, rusting, milk going sour

Signs of Change

Physical– Size– Shape– Texture

Chemical– Temperature– Color– Bubbles/fizzing– Smoke– Smell

Reactants: 

Products:

Chemical Change = _________________

In chemical changes, atoms and molecules re-arrange to form new substances.

Molecules in Chemical Changes

The atoms arrange to make a new substance

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

______________

•Liquid• • •

____________

•Powder/dry• • •

  I noticed the ……  

Mixing Things Up: Chemical Change Demos

Observations of Reactants:

•Observations during the demonstration:

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Question AnswerA chemical reaction between two materials occurs if the properties of the products (what you make) are different from the reactants (what you mix). Was what you observed today a chemical reaction? Explain!

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Chemical reactions have formulas just like molecules and compounds. As a class, we will write the chemical equation below and label the reactants and the products.Reactants:  

Products:

Reactants:  

Products:

Chemical Formula

In words

Chemical Reaction Demo

NaHCO3 NaOOCCH3

+ HOOCCH3 + H2O + CO2

Sodium Acetate, water, and carbon dioxide

Sodium Bicarbonate and Acetic Acid

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Summary:

• How can you tell if a chemical reaction happened?

• What are evidences to support that chemical reaction happened?

• After a chemical reaction will it be possible to bring back the reactants to their original form (state and properties)?

• How is chemical reaction related to chemical change?

Signs of Chemical Change

Fizzing/gas formation

Flash/light smoke

Change in temperatur

e

Smell/odor Change in color

Warm-upApril 21, 2023

Give an example of a physical change and a chemical change, and then describe how they are different from the other. Explain your answer in 2-3 sentences.

Warm-upApril 21, 2023

Why is cooking/baking similar to science? Explain your answer.

Physical Change vs. Chemical Change

Objective

To correctly identify and differentiate physical change from chemical change.

Question

Are changes (physical and chemical) only present inside the laboratory?How are physical change different from chemical change?

Hypothesis

If physical change does not produce a new product, then I can ….

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Steps Physical or

Chemical

Observations:

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Steps Physical or

Chemical

Breaking graham

crackers

Observations:

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Steps Physical or

Chemical

Breaking graham

crackers

Breaking

chocolate bar

Observations:

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Steps Physical or

Chemical

Breaking graham

crackers

Breaking

chocolate bar

Cooking

Marshmallow

Observations:

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Steps Physical or

Chemical

Breaking graham

crackers

Breaking

chocolate bar

Cooking

Marshmallow

Stacking cracker,

chocolate, and

marshmallow

Observations:

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Steps Physical or

Chemical

Breaking graham

crackers

Breaking

chocolate bar

Cooking

Marshmallow

Stacking cracker,

chocolate, and

marshmallow

Chocolate melting  

Observations:

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Steps Physical or

Chemical

Breaking graham

crackers

Breaking

chocolate bar

Cooking

Marshmallow

Stacking cracker,

chocolate, and

marshmallow

Chocolate melting  

Eating smore!  

Observations:

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Discussion/Summary:

• How will you know if an object underwent a chemical or physical change?

• Can changes happen outside of the science classroom or laboratory?

Physical Change v. Chemical ChangeMake a Venn Diagram to compare the 2 types

of changes

Is it a chemical or physical change?

Sugar dissolving in tea

•Chemical Change

•Physical Change

OOPS!

Did it change size, color, shape (Physical Change)?

orDid it become different matter (Chemical

Change)?

Correct!

Is it a chemical or physical change?

Logs burning

•Chemical Change

•Physical Change

OOPS!

Did it change size, color, shape (Physical Change)?

orDid it become different matter (Chemical

Change)?

Correct!

Is it a chemical or physical change?

Breaking water up by separating it into hydrogen and oxygen

•Chemical Change

•Physical Change

OOPS!

Did it change size, color, shape (Physical Change)?

orDid it become different matter (Chemical

Change)?

Correct!

Is it a chemical or physical change?

Cutting paper

•Chemical Change

•Physical Change

OOPS!

Did it change size, color, shape (Physical Change)?

orDid it become different matter (Chemical

Change)?

Correct!

Is it a chemical or physical change?

Crushing an aspirin

•Chemical Change

•Physical Change

OOPS!

Did it change size, color, shape (Physical Change)?

orDid it become different matter (Chemical

Change)?

Correct!

Is it a chemical or physical change?

Metal rusting

•Chemical Change

•Physical Change

OOPS!

Did it change size, color, shape (Physical Change)?

orDid it become different matter (Chemical

Change)?

Correct!

Is it a chemical or physical change?

An egg rotting

•Chemical Change

•Physical Change

OOPS!

Did it change size, color, shape (Physical Change)?

orDid it become different matter (Chemical

Change)?

Correct!

Is it a chemical or physical change?

An egg breaking

•Chemical Change

•Physical Change

OOPS!

Did it change size, color, shape (Physical Change)?

orDid it become different matter (Chemical

Change)?

Correct!

Standards 8.5.c.

I know chemical reactions usually liberate or absorbs heat.

Endothermic and Exothermic Reactions

When chemical reactions occur, the connections between atoms must be broken and rearranged. In order to do this, ________________ is involved in all chemical reactions.

Heat

There are 2 Types of Reactions Involving Heat

Endothermic Exothermic• Within-Heating

• Endo = Enter

• Therm/ic = Heat

• Outside-Heating

• Exo = Exit• Therm/ic = Heat

There are 2 Types of Reactions Involving Heat (cont.)

Endothermic

Exothermic

• Reactions in which the system absorbs heat from the surrounding.

• Reactions in which the system releases heat to the surrounding.

There are 2 Types of Reactions Involving Heat (cont.)

Endothermic

Exothermic

It feels: It feels:Cold Hot

There are 2 Types of Reactions Involving Heat (cont.)

Endothermic

Exothermic

Examples: Examples:• Cooking an egg

• Baking a bread

• Candle flame

• Rusting Iron

Frayer Model

Exothermic Reaction

Frayer Model

Endothermic Reaction

Chemical Change = Reaction

Products: the resulting solutions in a reaction

Reactants: starting solutions in a reaction

Weekly Reflection/Exit Slip• Name 4 items you

learned in this week’s lesson.

• If Mr. Rivera will teach the lesson again, will you want it done differently?

• If you want it done differently, why and how would you want it?

• If you want it done the same, why?