How can you recognize that an exothermic reaction has occurred?

Question

Question 1 options:

The reaction will release heat

The reaction will absorb heat

The reaction will create a precipitate

The reaction will change color
Question 2 (1 point)
Strontium phosphate, Sr3(PO4)2, is a crystalline substance used in medicine and industry. How many phosphorus atoms are represented in the formula for Sr3(PO4)2?
Question 2 options:

8

3

4

2
Question 3 (1 point)
What is the difference between a molecule and a compound.
Question 3 options:

In a molecule, two or more same atoms are connected with the chemical bonds. However, in a compound, two or more, same or different atoms and molecules are connected.

In a molecule, two or more same compounds are connected with the chemical bonds. However, in a compound, two or more, same or different atoms and molecules are connected.

In a molecule, two or more same molecules are connected with the chemical bonds. However, in a compound, two or more, same or different atoms and molecules are connected.

In a molecule, two or more same atoms are connected with the chemical bonds. However, in a molecule, two or more, same or different atoms and molecules are connected.
Question 4 (1 point)
What kind of reaction is the reaction below? Mg(s) + CuSO?(aq) ? Cu(s) + MgSO?(aq)
Question 4 options:

Synthesis

Displacement

Decomposition

Elimination
Question 5 (1 point)
Which of the following is NOT evidence that a chemical reaction has occurred?
Question 5 options:

Change in size

Gas production

Changes in properties

Changes in temperature
Question 6 (1 point)
Which substances form due to a chemical reaction?
Question 6 options:

Mass

Products

Atoms

Reactants
Question 7 (1 point)
A silver ring reacts with compounds containing sulfur in the air to form silver sulfide, a black substance that makes up the tarnish on the surface of silver objects. To remove the tarnish from the ring, students placed it in a pan lined with aluminum foil and added hot water. Baking soda was added to the hot water and stirred. Students made observations about the process.

Which observation of this process provides evidence of a chemical reaction?

Question 7 options:

Hot water heated the aluminum foil.

The liquid solution changed color.

The pan was lined with aluminum foil.

The hot water cooled.
Question 8 (1 point)
I. Car metal rusting slowly for a year.

II. Condensation of water vapor on a mirror during a 5-minute shower.

III. The formation of a precipitate in a test tube during a 10-second reaction.

IV. The oxidation of copper on the Statue of Liberty for more than 100 years.

Which of the processes above are examples of a chemical reaction?

Question 8 options:

I and II

III and IV

I, II, and III

I, III and IV
Question 9 (1 point)
A student placed 2 grams of baking soda in a balloon and 100 mL of vinegar in an Erlenmeyer flask. After stretching the opening of the balloon across the neck of the flask, the student raised it to dump the baking soda into the flask. He immediately observed foaming bubbles in the flask and the balloon began to expand.

An accurate conclusion would be that --

Question 9 options:

only a physical change was occurring

the baking soda and vinegar were products of a chemical reaction

oxygen gas was produced

the bubbles indicated a chemical change was occurring
Question 10 (1 point)
During chemistry lab, Mrs. Black?s students placed an antacid tablet in a zip lock bag. They recorded the mass of the tablet in the bag. Then they carefully added 50 grams of water and quickly sealed the bag. The tablet began to fizz and soon disappeared. The bag was filled with gas and it felt cold to the touch.

What type of change occurred in the bag and how can you support your answer?

Question 10 options:

It is a physical change because the tablet dissolved.

It is a chemical change due to the change in temperature and gas production.

It is a chemical change because the tablet dissolved and the temperature of the liquid dropped.

It is a physical change as evidence by change in temperature.

Answer 1

1. The reaction will release heat.
5. Change in size
6. Products
7. The liquid solution changed color.
8. III and IV
9. The bubbles indicated a chemical change was occurring.
10. It is a chemical change because the tablet dissolved and the temperature of the liquid dropped.

Answer 2

Question 2 (1 point)
Strontium phosphate, Sr3(PO4)2, is a crystalline substance used in medicine and industry. How many phosphorus atoms are represented in the formula for Sr3(PO4)2?
Question 2 options:

8

3

4

2
Question 3 (1 point)
What is the difference between a molecule and a compound.
Question 3 options:

In a molecule, two or more same atoms are connected with the chemical bonds. However, in a compound, two or more, same or different atoms and molecules are connected.

In a molecule, two or more same compounds are connected with the chemical bonds. However, in a compound, two or more, same or different atoms and molecules are connected.

In a molecule, two or more same molecules are connected with the chemical bonds. However, in a compound, two or more, same or different atoms and molecules are connected.

In a molecule, two or more same atoms are connected with the chemical bonds. However, in a molecule, two or more, same or different atoms and molecules are connected.
Question 4 (1 point)
What kind of reaction is the reaction below? Mg(s) + CuSO?(aq) ? Cu(s) + MgSO?(aq)
Question 4 options:

Synthesis

Displacement

Decomposition

Elimination

Answer 3

Question 2: There are 4 phosphorus atoms represented in the formula for Sr3(PO4)2.

Question 3: In a molecule, two or more same atoms are connected with the chemical bonds. However, in a compound, two or more, same or different atoms and molecules are connected.

Question 4: The reaction is a displacement reaction.