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What do fireworks, a fried egg, and a rusting vehicle have in common? They all involve chemical reactions. If two or more elements or chemical compounds come into contact with one another and there is enough energy present, a chemical change may take place.

When a substance undergoes a chemical change, the chemical structure of that substance is altered. A chemical change can also be called a chemical reaction. During a chemical reaction a new substance is formed.

Observe the chemical reaction between bromine and aluminum. Pieces of aluminum are cut from a strip of foil and added to liquid bromine. At first there is no reaction because of the protective oxide coating on the aluminum. But soon an exothermic reaction between bromine and aluminum causes brown fumes of bromine to be given off. But as a new substance, aluminum bromide is produced. White smoke is produced.

The resulting residue is also aluminum bromide. When two compounds or molecules react together to form new substances, they are called reactants. They new substances created plus any resulting ash, water vapor, or carbon dioxide are called products, because they are produced by the reaction.

Some chemical reactions, such as the explosion of fireworks, can happen very fast—in less than a second.

Others, like the rusting of a car, might take years. It is important to carefully examine chemical reactions because there are many ways substances can be changed without a chemical reaction taking place.

Changes of state, for example, from a solid to a liquid or from a liquid to a gas, always involve a physical change rather than a chemical one. Melting sulfur is a good example. When solid sulfur is heated to 120 degrees Celsius it melts and first forms a pale yellow liquid.

In this form the atoms are covalently bonded and the liquid can flow easily. However, heated up beyond 150 degrees Celsius, the result is a dark red liquid that is over 2,000 times stickier. The sulfur may have changed physically but it's still sulfur.

No chemical reaction has taken place. Most of the time changes of state can be reversed by either adding or taking away heat. When water is boiled, for example, water vapor molecules are released in the process.

If you captured all the vapor molecules in a container they would reform again as water droplets once the vapor cooled. When a chemical change occurs it is more difficult to revert the substance back to its original state.

Answer:

this is answers to the second picture

Explanation:

1-   energy

2- structure

3- reaction

4- substance

5- reactants

6- products

7- changed

8- At first there is no reaction because of the protective oxide coating on the aluminum. But soon an exothermic reaction between bromine and aluminum causes brown fumes of bromine to be given off. But as a new substance, aluminum bromide is produced. White smoke is produced.

9-   heated to 120 degrees Celsius it melts and first forms a pale-yellow liquid.

In this form the atoms are covalently bonded, and the liquid can flow easily. However, heated up beyond 150 degrees Celsius, the result is a dark red

10- When a chemical change occurs it is more difficult to revert the substance back to its original state. (To be honest I don't know)

Iodine-138 decays by beta decay. What element does it produce?

Plz, Help! Read the instructions and answer the question! First one to answer will get brainliest!

A food scientist is determined to create a mango that looks exactly like a mango but tastes like salmon. Can this be achieved through artificial selection? Why or why not?

Based off of the simulation pulley gizmo; how many people did it take to lift the armchair with a fixed pulley? (Look at Activity A question 2)



Question 5 options:

1


3


4


5

speed =________

ate divided by time

rate divided by distance

distance divided by time

time divided by rate

I need answer asap! Plz someone help ! Ill give brainliest!

How does gravity act on an object?
1. exerts force upward on an object
2. repels objects
3. pulls objects towards the Earth
4. restores an object to its original position
Need answer asap!! First one to answer will get a brainliest!!

Which phrase describes a feature of groundwater?

-feeds rivers
--provides habitats
-makes up 75% of fresh water
--used for hydroelectric power

glacial striations in the bedrock of south africa indicate that glaciers once moved across the african continent the presence of glaciers on the surface of africa is evidence that

In a chemical reaction, the mass of the reactants is 13.3 grams. Which of the following could represent the mass of the products?

A. 26.6 grams.

B. 13.3 grams.

C. 39.9 grams.

D. 3.3 grams.

A submarine fills a special storage area known as ballast with water in order to increase its density. This allows it to dive deeper into the ocean. When a submarine needs to rise rapidly, compressed air is used to push the water out of the ballast. What effect does replacing the water in the ballast with air have on the submarine?

In class we made salt crystals. To do this we put a supersaturated solution of salt into a glass of water. After a few days the water evaporated and the salt crystals were left on the paper cutouts. When the salt dissolved in the water was this a physical change or a chemical reaction? Please explain your answer in detail.

Plz, help! I need help with questions a and b! Plz, write your answer in complete sentences! And the first person to answer will get a brainliest! Plz, NO SCAM links!!!!!!!

It takes Mark two hours to ride his bike 12 miles to his grandma’s house. What is Mark’s speed in miles per hour? I need an answer asap! And you also have to show your work so plz do that!
First one to answer will get a brainliest

What will a soccer player need to do to change a ball’s position?
1. He must apply gravity to the ball so that the ball will move.
2. He must weigh the ball to determine the motion that needs to occur.
3. He must set the ball in motion by applying a force in the desired direction.
4. He must identify the location of the ball.
First one to answer will get brainliest!

Plz help! Please write your answer in complete sentences and write a proper answer!
FIrst on to answer will get a brainliest!!! Thx!

why does atumn start in diffrent months of the year in north america and south america

Martin slowly pours an unknown liquid into a container that originally had some water in it. He is measuring the temperature in the container as he does this.

The temperature in the container rises very fast.

What kind of change is likely to be happening in the container?

A. A physical change.

B. A chemical change.

C. Neither a chemical nor a physical change, only a temperature change.

D. No evidence of any type of change.

Which of the following always changes when a substance undergoes a chemical change?
A. State of matter of the substance.

B. Arrangement of the atoms composing the substance.

C. Color of the substance.

D. Mass of the substance.

I NEED HELP ASAP PLZZZZ

PLS HELP DUE SOON(Ignore that wet thingy on my paper it’s my matcha latte it go on it lol)

This is the chemical formula of Nitrogen gas.

N₂

Which of the following is NOT true of nitrogen gas?

A. It is made of two atoms.

B. It is a molecule.

C. It is an element.

D. It is a compound.

HELPPPPP!!!!!!!!!!!!!!!!!!!!!!!!!!!! 30 POINTS!!!!!!!!!!!!!!

Mixing baking soda and vinegar is an example of an endothermic reaction. This means...
A. baking soda and vinegar are products in this reaction.

B. energy is taken in during the chemical reaction.

C. energy is released during the chemical reaction.

D. there is no change in energy during the chemical reaction.

A submarine fills a special storage area known as a ballast with water in order to increase its density. This allows it to dive deeper in the ocean. When a submarine needs to rise rapidly, compressed air is used to push the water out of the ballast. What effect does replacing the water in the ballast with air have on the submarine?

Slow cooling of hot magma leads to the formation of ___________ crystals

List the communities in a successional sequence of secondary succession?

What causes the seasonal changes viewed in the night sky?

Shay constructed a scientific model of the carbon cycle. She included plants, animals, industry, fossil fuels, and the atmosphere. Which of the following arrows belongs in Shay’s model?

Is gravity alone sufficient to explain the behavior of the tinsel in the Levitating-orb system? Explain why.

6 CO₂ + 6 H₂0 → C₆H₁₂O₆ + 6 O₂

A. 6 CO₂

B. →

C. 6 H₂0

B. C₆H₁₂O₆