Free Printable Chemical Reactions

1.

Which of the following examples shows that a chemical reaction has occurred?

a)

A rock breaks into smaller pieces when it is struck with a hammer.

b)

Rust forms on a hammer that has been left outside to long.

c)

A cup of water turns pink when a few drops of red food coloring are added.

d)

A solid is formed when heat is removed from a sample of water.

2.

A student places a piece of a potato into a container of hydrogen peroxide. One observation the student makes is that bubbles form around the potato. The presence of bubbles might indicate the formation of a new substance because bubbles -

a)

could show that a gas is forming

b)

always rise to the top of a liquid.

c)

are almost always perfectly spherical.

d)

usually burst after a few minutes.

3.

Hydrogen peroxide breaks down to form water and oxygen gas. Which observation is evidence that a chemical reaction has occurred?

a)

The mass of the solution remains the same.

b)

Phase changes are observed.

c)

The color of the solution remains clear.

d)

The temperature of the solution increases.

4.

Which of the following is an example that includes evidence of a chemical reaction?

a)

A sample of zinc is placed in water and it settles to the bottom

b)

A solid block of ice is heated and it completely melts into a liquid.

c)

Sugar that is burned gives off an odor and turns brown and then black.

d)

A tomato is placed into a blender and chopped up into smaller pieces.

5.

Evidence of a chemical reactions is anything that shows -

a)

a new substance has formed

b)

a solid dissolved in a liquid

c)

interaction between 2 gases

d)

a change in the state of matter

6.

A precipitate is a

a)

liquid that forms when two solids are reacted

b)

a solid that forms when two liquids are mixed

c)

a gas that forms when vinegar and baking soda react

d)

a change of color in a solution

7.

What is the Law of Conservation of mass?

a)

Mass is created in a chemical reaction

b)

Mass is created in a physical change

c)

New chemicals formed from a chemical reaction have a larger overall mass than the original reactants

d)

Mass is never created or destroyed

8.

Mr. Brady did an experiment. The mass he started with was 15 grams. How much mass should he end with?

a)

less than 15 grams

b)

more than 15 grams

c)

15 grams

9.

The substances at the beginning of a chemical equation are called the ____

a)

product

b)

yield

c)

chemical symbol

d)

reactants

10.

In a chemical reaction, everything to the right of the arrow is called ______________.

a)

Products

b)

Yields

c)

Molecules

d)

Reactants

11.

In the equation, 2Mg + O₂ ---> 2MgO, which are the reactants?

a)

Mg and O

b)

MgO

c)

Mg and MgO

d)

O and MgO

12.

Which chemical formula below indicates that you have three molecules of water ( $H_2O$ )?

a)

$3H_2O$

b)

$H_6O_3$

c)

$6HO$

d)

$H_2O$

13.

Which formulas below have coefficients of 4? Check all that apply.

a)

$4CO_2$

b)

$4CH_4$

c)

$4H_2O_2$

d)

$4Br_3$

14.

Which chemical formula below matches the image shown here?

a)

$2H_2O$

b)

$H_4O_2$

c)

$4H2O$

d)

$2HO$

15.

Which chemical formulas indicate that there are two molecules of the substance? Check all that apply.

a)

$2H_2O$

b)

$3H_2O$

c)

$2I_3$

d)

$2NaCl$

16.

Which chemical formula below indicates that you have three molecules of sulfuric acid ( $H_2SO_4$ )?

a)

$6H_2SO_4$

b)

$3H_2SO_4$

c)

$2H_2SO_4$

d)

$H_2SO_4$

17.

The blue numbers in the image below represent ________

a)

I don't know, and don't want to try

b)

coefficients

c)

subscripts

d)

none of the answers are correct

18.

The red numbers in the image below represent ________

a)

subscripts

b)

coefficients

c)

I don't know, and don't want to try

d)

None of the answers are correct

19.

How many Sodium (Na) are in 6NaCl?

a)

1

b)

12

c)

6

20.

If there is no subscript, there is ______ atom(s) of that element.

a)

0

b)

2

c)

only 1

d)

1 million

21.

How many molecules are in 10MgCl₂?

a)

10

b)

2

c)

30

d)

13

22.

What are the products of the chemical reaction pictured?

a)

CH₄ and CO₂

b)

CH₄ and O₂

c)

CO₂ and H₂O

d)

O₂ and H₂O

23.

If reaction starts with 20g of reactants it should produce

a)

a total of 40g of products

b)

a total of 10g of products

c)

a total of 80 g of products

d)

a total of 20g of products

24.

Matter can not be created nor destroyed: it can only be

a)

Destroyed a little bit

b)

Invisible

c)

Transformed, changed

d)

None of the above

25.

Which of these is not a chemical reaction?

a)

Burning of wood

b)

Milk going bad

c)

Mixing vinegar and baking soda

d)

Melting of ice

26.

The coefficient in 3H₂O is

a)

6

b)

2

c)

3

d)

5

27.

According to the Law of Conservation of Mass, what happens to the wood and oxygen when it is burned?

a)

The wood disappears.

b)

It stays the same chemically.

c)

The atoms in the wood and oxygen rearrange and form smoke and ash.

d)

Nothing.

Chemical Reactions

Total questions: 27

Worksheet time: 20mins

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