Counting Atoms & Law of Conservation of Mass

Front

What does the law of conservation of mass state?

Back

Atoms are neither created nor destroyed in chemical reactions.

Front

How many atoms of aluminum are in the equation: 4Al + 3O₂ → 2Al₂O₃?

Back

4

Front

How many Nitrogen atoms are in (NH₄)₂CrO₄?

Back

2

Front

Fill in the blanks with coefficients: PCl₅ + _ H₂O → _ HCl + H₃PO₄

Back

4, 5

Front

How many Oxygen atoms are in 2Al₂(SO₄)₃?

Back

24

Front

What is a coefficient in a chemical equation?

Back

A number placed in front of a chemical formula to indicate how many molecules or atoms are involved in the reaction.

Front

What is the purpose of balancing a chemical equation?

Back

To ensure that the number of atoms for each element is the same on both sides of the equation.

Front

What is the formula for calculating the total number of atoms in a compound?

Back

Add the number of atoms of each element, multiplied by their respective subscripts.

Front

In the compound Ca(NO₃)₂, how many total Oxygen atoms are present?

Back

6 (2 from Ca(NO₃)₂, each NO₃ has 3 O atoms, so 2 x 3 = 6).

Front

What is the significance of subscripts in a chemical formula?

Back

Subscripts indicate the number of atoms of each element in a molecule.