Counting Atoms and Chemical Formulas

What is the right ratio of chemicals for the BCE (Balanced Chemical Equation)?__Na + __H₂O --> __NaOH + __H₂

• 2,2 --> 2,1

• 4,4 --> 4,1

• 1,2 --> 2,4

• 1,2 --> 2,1

Tags

NGSS.MS-PS1-5

Coefficients in chemical formulas...

• Multiply just the first atom

• Add to the subscripts at the end of the molecule

• Multiply elements without subscripts

• Multiply EVERYTHING!

4CF₂Cl₂

• C = 4, F = 4, Cl = 2

• C = 1, F = 8, Cl = 8

• C = 4, F = 8, Cl = 8

• C = 1, F = 4, Cl = 8

Tags

NGSS.MS-PS1-1

How many different elements are present in this molecule?

3 NH₄C₂H₃O₂

• 15

• 36

• 5

• 4

Tags

NGSS.MS-PS1-1

A ______ is a number written in front of a chemical formula.

• Coefficient

• Subscript

• Exponent

• Coordinator

2H₂ + O₂ ----> 2H₂O What is the product?

• ------>

• 2H₂O

• 2H₂+ O₂

Tags

NGSS.MS-PS1-1

NGSS.MS-PS1-5

How many O's are in Al₂(SO₄)₃

• 4

• 12

• 7

• 24

Tags

NGSS.MS-PS1-1

The law of conservation of matter states that

• chemical reactions change matter.

• in chemical reactions, the identity of reactants and products is conserved.

• atoms are neither created nor destroyed in chemical reactions.

• a chemical equation must be balanced.

Tags

NGSS.MS-PS1-5

Why is the following chemical equation not balanced?
H_{2 +} O₂ --> H₂O

• each side of the equation has a different number of oxygen atoms

• each side of the equation has a different number of hydrogen atoms

• each side has the same mass

Tags

NGSS.MS-PS1-5

Is the following equation balanced or unbalanced?
Fe + S --> FeS

• balanced

• unbalanced

Tags

NGSS.MS-PS1-5