Parts of Chemical Equations

What is a chemical equation?

• Describes the number of elements in a compound.

• One or two letters that represent the elements on the periodic table.

• The number to the lower right of an element that shows the number of atoms bonded.

• A written description of a chemical reaction.

Tags

NGSS.MS-PS1-1

Which numbers are coefficients in this equation?

• 3 and 8

• 3, 8, 2, 2, 2

• 1, 5, 4, 3

• 5, 4, 3

Answer explanation

The coefficients are the large numbers in front of the molecule. It shows how many of this molecule are involved in the reaction.

Tags

NGSS.HS-PS1-7

Which is/ are the reactant(s) in this equation?

• C₃H₈

• C₃H₈ and O₂

• H₂O and CO₂

• H₂O

Answer explanation

The reactants are the molecules on the left side of the reaction arrow.

Tags

NGSS.MS-PS1-2

NGSS.MS-PS1-5

How many oxygen atoms are there on the reactants side of the equation?

• 5

• 2

• 7

• 10

Answer explanation

the sbscript shows there are 2 oxygen atoms in each molecule and 5 molecules. 2 x 5 = 10 atoms

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-2

NGSS.MS-PS1-5

Which numbers are subscripts in this equation?

• 3, 8, 2, 2, 1, 1, 2

• 3, 8, 2, 2, 2

• 1, 5, 4, 3

• 5, 4, 3

Answer explanation

The subscripts are the small numbers to the right of the element. It shows how many of this element are included in the molcule.

Tags

NGSS.MS-PS1-5

What elements are present here?

• 6 hydrogen, 6 oxygen and 3 carbon

• 8 hydrogen, 10 oxygen, and 3 carbon

• 8 hydrogen, 6 oxygen and 6 carbon

• 8 hydrogen, 3 oxygen and 3 carbon

Tags

NGSS.MS-LS1-6

NGSS.MS-LS2-3

The red numbers in the image below represent ________

• subscripts

• coefficients

• I don't know, and don't want to try

• None of the answers are correct

What are the larger numbers that you CAN CHANGE in a chemical equation?

• Coefficient 

• Products

• Reactants

• Subscripts

What is a coefficient?

• The small number on the right of the chemical symbol.

• The large number in front of a chemical formula.

• The number in between the chemical symbols.

• The number behind a chemical formula.

Tags

NGSS.MS-PS1-5

How many HCl molecules do you need to balance this equation? Mg + __HCl ---> MgCl2 + H2

• 1

• 2

• 3

• 4

Tags

NGSS.MS-PS1-5