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Chemical Changes

Total questions: 20

Worksheet time: 1hrs 12mins

Name
Class
Date
1.
Which of the following is a sign that a chemical reaction has occurred?
a)
change in shape
b)
melting
c)
formation of a gas
d)
dissolving
2.
what is the definition of chemical change?
a)
any change that results in the formation of new chemical substances. 
b)
changing clothes
c)
matter cannot be created or destroyed, only change form
d)
changes affecting the form of a chemical substance, but not its chemical composition.
3.
The formula below represents the most common carbohydrate known as glucose. Which information can be determined from the chemical formula?
C6H12O6
a)
The structural arrangement of the atoms in a glucose molecule
b)
The color of a glucose molecule
c)
The size of a glucose molecule
d)
The number of atoms of each element in a glucose molecule
4.
The reactants are on the left side of the chemical equation.
a)
True
b)
False
5.
Two clear colorless solutions were combined.
The student observed that the temperature changed from 25 •C to 23 •C when the solutions were combined and that a white substance rapidly formed and settled to the bottom of the container. What most likely happened to produce these results?
a)
One of the original compounds came out of solution
b)
The solutions reacted chemically
c)
Some of the water froze into ice crystals
d)
Rapid evaporation of water occurred, leaving a solid
6.

How many atoms in all are in a molecule of serotonin?

C10H12N2O

a)
22
b)
24
c)
25
d)
4
7.
All of the following reactions are correctly balanced except-
a)
A
b)
B
c)
C
d)
D
8.

Which of these is NOT a sign that a chemical change has occurred?

a)

A loss of transparency

b)

An unexpected color change

c)

A temperature change

d)

The formation of a precipitate

9.

The Law of Conservation of Mass states

a)

that matter exists in all states and reacts the same

b)

that matter can only be changed into new substances by introducing a catalyst

c)

that matter exists in the same state throughout any chemical change

d)

that matter cannot be created or destroyed and that the mass of the products must equal the mass of the reactants

10.

How many Al atoms are in this compound? 4Al2O3

a)

2

b)

8

c)

6

d)

4

11.

How many F atoms are in this compound?

6MgF2

a)

2

b)

6

c)

8

d)

12

12.

___________________ are the elements or compounds that leave (are formed in) a chemical reaction.

a)

Polymers

b)

Bonds

c)

Reactants

d)

Products

13.
What is a coefficient?
a)
The small number on the right of the chemical symbol.
b)
The large number in front of a chemical formula.
c)
The number in between the chemical symbols.
d)
The number behind a chemical formula.
14.
Is the equation balanced?: 2H2O + O2 --> 4MgO + 3Fe
a)
Yes
b)
No
15.
What goes in the missing blanks?
SnO2 + __ H2 → Sn + __ H2O
a)
5
b)
1
c)
3
d)
2
16.
At the end of chemical reactions, what is the total mass of the reactants compared to the total mass of the products?
a)
the product is doubled
b)
the product is half the mass of the reactants
c)
the mass is the same
d)
the mass changes depending on the reaction
17.
What is the part of the chemical equation in green called? 
Fe + S --> FeS
a)
products
b)
reactants
c)
yield
d)
chemical formula
18.
What is the little number after an element in a chemical equation called.
Example: H2
a)
Coefficient 
b)
Subscript
c)
Atom
d)
Equation
19.
Balance this equation.
_CF4 + _Br2 -- _CBr4 + _F2
a)
2,1,2,1
b)
1,2,2,1
c)
1,2,1,2
d)
2,2,2,2
20.
When balancing equations a ____ can be placed to the left of a formula of a substance to make the equations balanced
a)
charge
b)
subscript
c)
random number
d)
coefficient