Dual Enrollment Physical Science Midterm Practice Test

These numbers are called coefficients. They sit in front of each chemical formula to show how many molecules (or moles) of that substance are involved in the reaction. When you balance an equation, you adjust these coefficients so that the same total number of atoms of every element appears on both sides of the arrow. That balance reflects the law of conservation of mass: nothing is created or destroyed, only rearranged into different substances. The coefficients multiply the entire formula, so they scale the entire molecule, not just parts of it. Subscripts, by contrast, are the small numbers inside a chemical formula that tell you how many atoms of each element are in a single molecule; those don’t change during balancing. Molarities are about concentration, and proportions are general ratios, not the specific quantities used to balance an equation.