Yuxin Science Class

Physical/Chemical Changes

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Physical Chemical Changes

Multiple Choice

Which of the following is a sign that a chemical reaction has occurred?

• change in shape
• melting
• formation of a gas
• dissolving

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

A ___ change causes the substance to change to a new substance with different properties.

• Physical

• Chemical

Multiple Choice

True or False: All atoms are created or destroyed in a chemical reaction.

• true

• false

• maybe

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

How do you know that rusting is a chemical change?

• it changes color

• atoms were rearranged to form a new substance

• we just know

• the rust

Multiple Choice

What property of metals does the term conductivity describe? (HINT: Think back to 6th grade.)

• reactivity with other elements

• melting & freezing point

• ability to transfer heat and electrcity

• density

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

What does an element's location on the periodic table tell you?

• info about the properties of the element

• importance & abundance if the elements

• order of discovery

• alphabetical order

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

The following are examples of evidence of a chemical reaction....

• ice melting into a liquid

• condensation

• endothermic reaction

• change in color, production of gas bubbles

Multiple Choice

Is melting butter for popcorn a chemical or physical change?

• chemical
• physical

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

What is the main idea behind how the Galileo Thermometer works?

• density in water changes as temp changes, which causes the bulbs in the water to either float or sink depending on its density to the water

• the bulbs either sink or float when they want to

• there is no main way; it just does it

Multiple Choice

A solid rubber ball sinks when placed in water. What will happen if the ball is cut in half and one of the smaller pieces is placed underwater?

• the smaller piece will sink

• the smaller piece will rise and float in the middle

• the smaller piece will float

• the smaller piece will dissolve

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

Elements are called the building blocks of matter because.....

• they are pure substances

• they are often used to build things

• all matter is made up of one or more elements

• elements have mass & volume

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

A test was done on milk and orange to see which was more acidic. The milk had a pH of 6.5 and the o.j. had a pH of 4. Which one was more acidic?

• milk

• orange juice

• neither

Multiple Choice

Ice (solid) can change to a liquid (water). This is a demonstration of a ______________________.

• physical change

• chemical change

• neither

• density

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

Ice cubes (made of fresh water) float higher in salt water, than ice cubes (made of fresh water) in fresh water (non-salt), why is this?

• fresh liquid water and ice have the same density

• frozen fresh water is more dense than salt water

• salt water is more dense than frozen fresh water

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

Sometimes I notice rust on the metal part of the nozzle of my garden hose, how or why scientifically does this happen?

• water running through the nozzle causes it to rust

• rust or corrosion appear on metals over time

• nozzle was damaged and exposed to water

• iron in metal nozzle combined with oxygen in the air to form rust or iron oxide

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

What do we know about the density between hot and cold water?

• cold water is less dense than hot water; therefore, cold water rises

• cold water is less dense than hot water; therefore, cold water sinks

• hot water is less dense than cold water; therefore, hot water rises

• hot water is less dense than cold water; therefore, hot water sinks

Multiple Choice

Which of the following is NOT an example of a physical change?

• crumpled paper
• pencil sharpening
• shrunken clothing
• rust

Multiple Choice

When we combine baking soda and vinegar, it fizzes and eventually turn into a liquid. What is actually happening?

• baking soda melted into its liquid form

• baking soda combined with the vinegar produced a new substance

• evaporated into the air

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

A pebble is dropped into a cup of water and sinks to the bottom of the cup. A metal bead (same size) is also dropped into the cup and sinks. How do the pebble and metal bead compare?

• both are denser than water

• both have the same density

• both have the same mass

• both have the same density as water

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

If an atom has 7 neutrons and 5 protons, how many electrons will it have?

• 2

• 7

• 5

• 12

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

If I combine baking soda and water, what type of change will I get?

• chemical change as baking soda dissolved

• physical change as baking soda dissolved

• neither chemical or physical

• water is neutral and doesn't produce a chemical change

Open Ended

What changes do you notice while cooking an egg?

Multiple Choice

The formula for calcium chloride is CaCl2. Which is the best response that explains what the formula means?

• chlorine is 2 times stronger than calcium

• two chlorine atoms are bonded to one calcium atom

• calcium and chloride have 2 covalent bonds

• chlorine is unstable until it bonds with 2 more calcium

Multiple Select

What key words, when present in a question about chemical reactions, might indicate a chemical change is occuring? Check all that apply.

• Bubbling

• Fizzing

• Dissolving

• Evaporating

Multiple Choice

What is pH?

• the scale used to measure how liquid something is

• the scale used to measure of the strength of an acid or base

• the scale used to measure how hot something is

• the scale used to measure how cold something is

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

What is matter? (Choose the BEST answer)

• anything that has mass and volume

• amount of space it takes up

• anything that has color

• amount of odor it has

Multiple Select

Which of the following does NOT indicate a chemical reaction is occuring? Check all that apply.

• Unknown A dissolves into Unknown B

• Unknown A creates fizzing and bubbles when combined with Unknown B

• Unknown A sinks to the bottom when added to Unknown B

• Unknown A floats to the top when added to Unknown B

Multiple Choice

A change where one or more new substances are created.

• Physical Change 
• Chemical Change 

Multiple Choice

Which of the following is a sign that a chemical reaction has occurred?

• change in shape
• melting
• formation of a gas
• dissolving

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

Is melting butter for popcorn a chemical or physical change?

• chemical
• physical

Multiple Choice

What is the definition of matter?

• anything that has mass and takes up space

• the amount of space that something takes up

• how tightly packed molecules are

• the mass of an object

Multiple Choice

A solid piece of chocolate is melted and changed to liquid form. Which property of the piece of chocolate will remain the same?

• Texture
• Temperature
  
• Shape
•  Mass

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

A change where one or more new substances are created.

• Physical Change 
• Chemical Change 

Multiple Choice

Fizzing, foaming, and burning are all examples of

• Chemical change
• Physical change

Multiple Choice

Change in color is a physical change.

• True
• False

Multiple Choice

• Physical Change
• Chemical Change

Multiple Choice

Fizzing, foaming, and burning are all examples of

• Chemical change
• Physical change

Matter can not be created or destroyed only changed!

Everything is made of matter, but what is matter made of ?

Multiple Choice

Rust on an iron bar is an example of chemical change.

• True 
• False

Multiple Select

What key words, when present in a question about chemical reactions, might indicate a chemical change is occuring? Check all that apply.

• Bubbling

• Fizzing

• Dissolving

• Evaporating

Multiple Choice

Burning wood

• physical change

• chemical change

Multiple Choice

When you break a cracker into pieces it is a...

• Chemical change
• Physical change

Multiple Choice

Acid in stomach, breaking down food.

• physical change

• chemical change

Multiple Select

Which of the following does NOT indicate a chemical reaction is occuring? Check all that apply.

• Unknown A dissolves into Unknown B

• Unknown A creates fizzing and bubbles when combined with Unknown B

• Unknown A sinks to the bottom when added to Unknown B

• Unknown A floats to the top when added to Unknown B

Multiple Choice

Which of the following is a sign that a chemical reaction has occurred?

• change in shape
• melting
• formation of a gas
• dissolving

Multiple Choice

Which of these is a result of a chemical change?

• A mixture
• A solution
• A new substance
• Melting or freezing

Multiple Choice

Is melting butter for popcorn a chemical or physical change?

• chemical
• physical

When atoms react by creating chemical bonds, they form molecules.
The molecules formed from chemical reactions are completely different substances with different properties.
Ex. Na which is explosive and Cl which is poisonous combine to form common table salt.

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​Compounds

Multiple Choice

A solid piece of chocolate is melted and changed to liquid form. Which property of the piece of chocolate will remain the same?

• Texture
• Temperature
  
• Shape
•  Mass

Multiple Choice

Ice melting

• Chemical Change
• Physical Change

Multiple Choice

A change where one or more new substances are created.

• Physical Change 
• Chemical Change 

Multiple Choice

Change in color is a physical change.

• True
• False

Multiple Choice

Water freezing

• Chemical Change
• Physical Change

Multiple Choice

Fizzing, foaming, and burning are all examples of

• Chemical change
• Physical change

Multiple Choice

A ____ change only changes the look of the substance but NOT the chemical make-up.

• Physical

• Chemical

Multiple Choice

Rust on an iron bar is an example of chemical change.

• True 
• False

Multiple Choice

Wood burned in a fireplace

• Chemical Change
• Physical Change

Multiple Choice

Burning wood

• physical change

• chemical change

Multiple Choice

Acid in stomach, breaking down food.

• physical change

• chemical change

Multiple Choice

Shredding a piece of paper

• Chemical Change
• Physical Change

Compounds have common names and chemical names. Ex. Ferrous Oxide is commonly called rust.
Compounds also have chemical formulae. Ex. H₂O, Fe₂0₃

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Chemical Names and Formulae

Multiple Choice

Boiling water

• Chemical Change
• Physical Change

Multiple Choice

What type of change has taken place in the following scenario:

Ice melts into water

• Chemical

• Physical

Multiple Select

What form of energy is being CREATED here? There is more than one answer!

• Electrical

• Thermal

• Radiant (Light)

• Mechanical

Atoms

The basic unit of all matter is the atom. Atoms are too small to be seen even with a microscope.

An average person is made up of 7 x 10²⁷ atoms. That is 7 followed by 27 zeros. Most of the atoms that make us up are Hydrogen atoms, oxygen atoms and carbon atoms.

Multiple Choice

When your food energy is made into energy that you use to run, energy is changing from...

• Thermal to chemical

• Chemical to electrical

• Mechanical to electrical

• Chemical to mechanical

Multiple Choice

When you shiver because you are cold, you are transforming...

• Mechanical energy into thermal energy

• Chemical energy into radiant (light) energy

• Electrical energy into chemical energy

• Thermal energy into chemical energy

Chemical change or chemical reaction happens when atoms combine and create different substances.
Ex. Vinegar and baking soda form carbon dioxide and sodium acetate

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​Chemical Change

Multiple Choice

When you eat a meal and your temperature increases, you are transforming...

• Thermal energy into mechanical energy

• Radiant (light) energy into mechanical energy

• Chemical energy into mechanical energy

• Chemical energy into thermal energy

Multiple Choice

Is it a physical or chemical change?

• physical

• chemical

Multiple Choice

Which of the following is a sign that a physical change has occurred?

• Bubbles forming

• The object being broken into smaller pieces

• Heat being produced

• Light being produced

Multiple Choice

What kind of energy is food?

• Thermal energy

• Mechanical energy

• Solar energy

• Chemical energy

Multiple Choice

When you eat lunch and then talk to your friend, that is a conversion of...

• Chemical energy to sound energy

• Mechanical energy to wind energy

• Chemical energy into mechanical energy

• Sound energy into thermal energy

Chemical equations show which substances are used in a chemical reaction.
It also shows at the ratio of the substances.
Reactants - the substances on the left.
Products - the resulting substances on the right.
Law of conservation of mass - the mass of the reactants and products are equal.

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​Chemical Equations

Multiple Choice

Which of the following is observed here?

• A physical change because you have the same types of atoms

• A physical change because you are just breaking the atoms up

• A chemical change because you are forming a new substance

• A chemical change because atoms are involved

Atomic Theory

1.All substances are made of atoms. Atoms are the smallest particles of matter. They can not be created or destroyed.

2.All atoms of the same element are alike and have the same mass. Atoms of different elements have different masses.

3.Atoms join together to form compounds. A given compound always consists of the same kinds of atoms in the same ration.

Multiple Choice

When water boils, there are bubbles. Therefore, it is a chemical change.

• True

• False

Multiple Choice

Is it a physical or chemical change?

• Physical

• Chemical

Signs of Chemical Change

Elements

Elements are substances that are made of the same kind of atom. They are all found on the Periodic Table of Elements.

Change in Color

Tarnishing

Releases Gas

Multiple Choice

Vinegar + baking soda reaction.

Is it a physical or chemical change?

• Physical

• Chemical

Forms a Precipitate

Releases Energy

Photosynthesis
Cellular respiration
Digestion
Combustion (fuel)
Batteries
Creation of Compounds (petrol products, plastics, etc.)

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​Everyday Chemical Reactions

Multiple Choice

Rusting is a chemical change.

• True

• False

Multiple Choice

Is it a physical or chemical change?

• Physical

• Chemical

Cooking and baking
Cleaning
Medicine
Traditional photography
Fermentation

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​Everyday Chemical Reactions

Multiple Select

Do you remember the three elements humans are mostly made of? Check the three that are correct.

• Hydrogen

• Calcium

• Oxygen

• Carbon

Multiple Choice

Baking a cake is what type of change?

• physical

• chemical

Multiple Choice

Rotting banana

Is it a physical or chemical change?

• Physical

• Chemical

Remember, elements are made of the same kind of atom!

Each atom of the substance is the same.

Multiple Choice

Is it a physical or chemical change?

• Physical

• Chemical

Multiple Select

Check all the substances that are considered elements.

• gold

• water

• oxygen

• carbon dioxide

• silver

Multiple Choice

Water + Kool-aid Powder.

Is it a physical or chemical change?

• Physical

• Chemical

Compounds

We have a little less than 100 naturally occurring elements in the universe that we know of BUT we have so many different kinds of matter around us. Elements combine in limitless ways to form Compounds.

Multiple Choice

The metal is rusting.

Is it a physical or chemical change?

• Physical

• Chemical

Multiple Select

Which of the following are compounds?

• Water

• H₂O

• Sugar

• Hydrogen

• CO₂

Multiple Choice

Leaves changing colors in the fall.

Is it a physical or chemical change?

• Physical

• Chemical

Multiple Choice

Mixing sugar and water.

Is it a physical or chemical change?

• Physical

• Chemical

Physical Changes

• Matter changes appearance

• Atoms DO NOT REARRANGE

• Change of State - Boiling, Melting, Evaporativng

• Dissolving

Multiple Select

Choose all of the following that are PHYSICAL changes.

Multiple Choice

Which of the following is an example of a physical change?

• mixing baking soda and vinegar causing bubbles to form

• dissolving sugar into sweet tea

• heating sugar until it turns black

• letting milk spoil, forming a solid from a liquid

Multiple Select

Choose all of the following that are CHEMICAL changes.

Chemical Changes

• change in matter where the ATOMS rearrange and

• Form a NEW substance that wasn't there before

Multiple Select

Mark all the examples that result in a chemical change.

• Cooking / Baking

• Boiling Water

• Rusting

• Tearing food with teeth

• mixing food with saliva and enzymes to break it down into glucose

Four Signs of Chemical Change

Gas/Bubbles/Fizzing

Increase/Decrease of Temperature

Change in color

Formation of Precipitate

Multiple Select

Check all the examples of a chemical change.

• Formation of a solid out of a liquid

• fizzing and bubbling after two liquids are mixed

• Salt Dissolving in Hot water

• Food broken down in by saliva in the mouth and acid in the stomach

• Leaves turning brown