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\ Classify the chemical changes as endothermic or exothermic.\ Pocket hand warmers, often used by skiers, start out at room temperature. When the air-tight packaging is opened, a substance contained in a cloth\ pouch reacts with air, and it quickly begins to feel hot.\ A "cold pack," often used for sports injuries, starts out at room temperature, but squishing the liquid around causes two substances to mix that were