WEBVTT

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Here is the problem: Balance the chemical equation KMnO4 plus HCl → KCl plus MnCl2 plus H2O plus Cl2.

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Balance atoms of every element, then use the coefficients as mole ratios.

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Write an atom balance for each element. Give each species an unknown coefficient; atoms of every element must be equal on both sides.

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Solve the linear system with the smallest whole numbers. Exact elimination leaves one free coefficient; scaling by the least common denominator gives integers.

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Balanced equation.

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So the answer is 2KMnO4 plus 16HCl → 2KCl plus 2MnCl2 plus 8H2O plus 5Cl2.

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Coefficients in a balanced equation count particles (moles), not grams. Convert grams to moles, apply the mole ratio, then convert back to grams with the other species prime molar mass. Assumes the reaction goes to completion with the known species fully consumed (or formed).

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K: 2 equals 2, Mn: 2 equals 2, O: 8 equals 8, H: 16 equals 16, Cl: 16 equals 16, which checks out.