Question

categorize each change as physical change or chemical change.
a butane lighter produces a flame
a screwdriver left outside in the rain rusts
barium hydroxide mixed with ammonium chloride becomes colder
rubbing alcohol evaporates
silver tarnishes upon exposure to the air
sugar dissolves in water
water boils

Explanation:

• A butane lighter produces a flame: Chemical change (combustion of butane to form new substances like carbon dioxide and water).
• A screwdriver left outside in the rain rusts: Chemical change (iron reacts with oxygen and water to form rust - iron oxide).
• Barium hydroxide mixed with ammonium chloride becomes colder: Chemical change (a chemical reaction occurs between barium hydroxide and ammonium chloride).
• Rubbing alcohol evaporates: Physical change (change of state from liquid to gas without new substance formation).
• Silver tarnishes upon exposure to the air: Chemical change (silver reacts with sulfur compounds in air to form silver sulfide).
• Sugar dissolves in water: Physical change (dissolution is a physical process, no new substance formed).
• Water boils: Physical change (change of state from liquid to gas, no new substance formed).

Answer:

• Chemical change: A butane lighter produces a flame, A screwdriver left outside in the rain rusts, Barium hydroxide mixed with ammonium chloride becomes colder, Silver tarnishes upon exposure to the air.
• Physical change: Rubbing alcohol evaporates, Sugar dissolves in water, Water boils.