Baking powder = sodium bicarbonate + weak solid acid (usually tartaric acid or cream of tartar). On moistening, they react to produce CO₂, causing dough to rise without requiring external acidic ingredient.
Explanation:
Reacting with metals (e.g., Zn + 2HCl → ZnCl₂ + H₂) to produce hydrogen gas is a chemical property because new substances are formed. Sour taste is physical sensation, color change of litmus is an indicator of chemical reaction but is not itself a chemical property; reactivity is. Conductivity is physical. Chemical properties describe a substance's ability to undergo chemical change.
Explanation:
Plaster of Paris (CaSO₄·½H₂O) sets by rehydrating to gypsum (CaSO₄·2H₂O) when mixed with water: CaSO₄·½H₂O + 1½H₂O → CaSO₄·2H₂O. The interlocking crystals of gypsum provide hardness. It expands slightly on setting, making it ideal for casting. Dehydration is the opposite. Oxidation and carbonation are not involved.
Explanation:
Sodium bicarbonate (NaHCO₃) is an acidic salt because it contains a replaceable hydrogen atom (can neutralize bases). Its aqueous solution is mildly basic due to hydrolysis, but chemically it is an acid salt (formed by partial replacement of H of carbonic acid). K₂SO₄ is normal salt, CaOCl₂ is mixed salt, Na₂CO₃ is normal salt. Acid salts can react with bases.
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