Types of Reactions Review

Students reported that the bottle felt colder after the reaction. The experiment was repeated and the temperature of the liquid in the bottle was recorded. Temperature before the reaction = 20ºC;

After the reaction = 15ºC

What is the best explanation for this change in temperature of the reactants?

• An endothermic reaction occurred

• The liquid was starting to freeze

• An exothermic reaction occurred

• The room became colder

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-4

NGSS.MS-PS3-4

NGSS.MS-PS3-5

Students recorded their observations from the reaction. Select the three observations that would indicate a chemical change.

• the bottle felt colder after the baking soda was added

• the baking soda and vinegar became a mixture

• 
  the balloon inflated

• the baking soda dissolved in the vinegar

• the baking soda and vinegar bubbled and fizzed

Tags

NGSS.MS-PS1-2

Which of the following is a chemical property of the element sodium?

• It is explosive in water.

• It is a solid at room temperature.

• It has a melting point of 97.81 °C.

• It is a good conductor of electricity.

Which observation is a sign of a chemical change?

• folding a paper airplane

• lights flashing from fireworks

• water turning to ice in a freezer

• iron filings sticking to a magnet

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NGSS.MS-PS1-2

NGSS.MS-PS1-5

The bond that forms between atoms when they share electrons is called a(n) (a)   bond.

• metallic

• ionic

• covalent

• element

Matter can be described and identified by physical and chemical properties. Physical properties have to do with appearance. You can observe many physical properties with your senses and by measuring the length, width, height, mass and density of a substance. Physical properties include color, shape, smell, texture, taste and size. The state of matter (whether it's a solid, liquid, or gas) and the temperature at which the substance boils, melts or freezes are also physical properties. Magnetic properties are physical properties as well. 

Chemical properties, on the other hand, have more to do with the atomic or molecular composition of matter. Chemical properties deal with how substances react with other substances such as water, air or fire.

A physical change has occurred when a substance changes color, size, shape, temperature or state. A chemical change has occurred when a substance has changed into something new or different so that the original substance is gone. Digestion and combustion are examples of chemical changes. A chemical change takes place in a battery to produce electricity when you turn on a flashlight.

You can observe chemical properties by...(Select more than 1 answer)

• Using your senses 

• Observing how a substance reacts with another substance 

• Measuring the length, width, height, mass and density of a substance

• Studying the molecular structure of the substance 

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Select ALL examples of chemical changes.

• Rotting

• Boiling

• Freezing

• Rusting

• Burning

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NGSS.MS-PS1-2

NGSS.MS-PS1-5

Select ALL examples of physical properties 

• Color

• Reactivity

• Density

• Flammability

• Electrical Conductivity

Which of the following processes is an example of a chemical change?

• Boiling water

• Breaking a glass window

• Burning a piece of wood

• Melting butter in a pan

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

What is a chemical property of the element chlorine?

• It reacts with sodium to form table salt.

• It is denser than air.

• It has a boiling point of -34.04 °C.

• It is a greenish-yellow gas at room temperature.