Law of Conservation of Mass Quiz

What does the law of conservation of mass state?

In an open system, gases are unable to escape during a reaction.

What should be equal on both sides of a balanced chemical equation?

Coefficients in a chemical equation indicate the amount of a particular chemical and the ______ of each reactant to products.

Match the following terms with their definitions:

What is the first step in balancing a chemical equation?

To balance an equation, you can change the subscripts of the chemical formulas.

What should you do if a polyatomic ion appears in both reactants and products during balancing?

Law of Conservation of Mass

States that mass cannot be created or destroyed in a chemical reaction.
Reactants' mass equals products' mass in a closed system.
Example: 5g hydrogen + 2.5g oxygen = 7.5g water (closed system).
Closed system: reaction in a sealed vessel (no gas escape).
Open system: reaction in an unsealed vessel (gas escape possible).

Application to Chemical Equations

Mass of each atom type remains constant.
Reactants' atoms (quantity) equal products' atoms (quantity), just rearranged.
Therefore, reactant and product masses are equal.

Coefficients in Chemical Equations

Coefficients precede chemical formulas to show quantities.
Coefficients give ratios of reactants needed for product ratios.
Used to make atom counts equal on both sides of the reaction.

Balancing Chemical Equations

Purpose: ensure equal atom numbers on each side (law of conservation).
Cannot change subscripts (changes the substance).
Only use coefficients to adjust atom counts.

Balancing Equation Order

First: balance elements other than hydrogen and oxygen.
Second: treat polyatomic ions as a whole unit (if present on both sides).
Third: balance oxygen.
Fourth: balance hydrogen.
Fifth: balance elements present separately.
Sixth: Double-check atom counts are equal.
Seventh: Reduce coefficients if possible.

Test your understanding of the Law of Conservation of Mass and its application in chemical reactions. This quiz will cover concepts such as closed and open systems, the role of coefficients in balancing chemical equations, and the importance of mass conservation in chemistry.