Ten processes commonly encountered in the household are listed below.
(i) Dissolving table salt in water
(ii) Evaporating vinegar to dryness
(iii) Burning a paraffin candle
(iv) Condensing water vapor on a cold surface
(v) Cooking an egg until the white solidifies
(vi) Dissolving sugar in hot coffee
(vii) Tearing aluminum foil into small pieces
(viii) Rusting of steel wool in moist air
(ix) Subliming mothballs made of naphthalene
(x) Charging a rechargeable lithium-ion battery
Some scientists argue that certain operations, such as dissolving salts, blur the line between physical and chemical change.
(a) Categorize each of the ten processes into one of three bins: Physical Change, Chemical Change, or Ambiguous/Gray Area. Display your classification in a three-column chart.
(b) Choose TWO processes you placed in the Ambiguous/Gray Area. For EACH, construct an argument that justifies why reasonable chemists might disagree about its classification, citing both intramolecular and intermolecular interactions.