Which metal reacts violently with cold water, producing a metal hydroxide, hydrogen gas, and enough heat for the hydrogen to catch fire?
Potassium
Reactivity with water follows the reactivity series: the most reactive metals (like potassium and sodium) react even with cold water, while less reactive ones react only with steam or not at all.
Potassium reacts violently with cold water: \(2K + 2H_2O \rightarrow 2KOH + H_2\), giving potassium hydroxide and hydrogen. The reaction is so exothermic that the heat ignites the evolved hydrogen, producing a lilac flame.
Calcium reacts far more gently with cold water and does not catch fire; magnesium reacts only slowly with hot water/steam; aluminium is protected by an oxide layer and does not react with cold water.
Hence, the metal is potassium.
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When electricity is passed through an aqueous solution of sodium chloride (called brine), it decomposes to form sodium hydroxide. This process is called:
When Barium Chloride (BaCl2) solution is mixed with Sodium Sulfate (Na2SO4) solution, a white product Barium Sulfate (BaSO4) is formed. This product is known as a ______.
Which of the following statements about carbon monoxide in the air is correct?
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When dilute Hydrochloric acid (HCl) reacts with Sodium Hydrogen Carbonate (NaHCO3), which is the product formed along with Sodium chloride (NaCl) and Water (H2O)?
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Important Questions from Chemical Reaction
Which of the following statement is/are true?
I. In physical change new substance is formed. substance is formed.
II. In chemical change no new substance is formed.
Which of the following cells involves similar chemical reactions?
The information not obtained from balanced chemical equation is
Oxygen cannot be obtained by which one of the following methods?
Which is the most reactive metal?
