Video narration
How do you know how much of each substance in a chemical reaction needs? A recipe answers that: two cups of one ingredient and one cup of another means measure them in that ratio. A balanced chemical equation works the same way. Its coefficients give the ratio of reacting substances. So it is not just symbols to memorize-it's a measuring recipe. How does that ratio connect to mass? A mole is a counting unit for tiny particles. Mass tells you how much matter you have. Use n equals m divided by M. Here, n means moles, m means mass, and M means molar mass. For water, M is eighteen grams per mole. If m is eighteen grams, n is one mole. Then use the equation's ratio to calculate the amount. So, how do you know it? Read the ratio, turn mass into moles-just like a recipe.