A chemical equation can be used to solve stoichiometry problems provided that it:

• A. contains only ionic compounds
• B. includes the reaction temperature
• C. is balanced
• D. shows the physical states of all reactants and products

Answer: (C)

Verified step by step guidance

1. Understand that a chemical equation must be balanced to correctly represent the conservation of mass, meaning the number of atoms of each element is the same on both sides of the equation.
2. Recognize that balancing the equation ensures the mole ratios of reactants and products are accurate, which is essential for stoichiometric calculations.
3. Note that the presence of ionic compounds or physical states is helpful but not mandatory for solving stoichiometry problems; the key requirement is the balanced equation.
4. Realize that reaction temperature is generally not required to solve basic stoichiometry problems unless the problem involves reaction kinetics or equilibrium.
5. Conclude that the fundamental criterion for using a chemical equation in stoichiometry is that it must be balanced to correctly relate quantities of substances.