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.
Similar Questions
- Which chemical process results in the formation of plaque on copper, the rusting of iron and the blackening of silver?
- What is oxidization?
- With which substance does silver react and turn black?
- Which of the following determines that a chemical reaction has not taken place?
- Which of the following solutions has the highest concentration of hydrogen ions?
- Which of the following product is formed due to burning of a magnesium ribbon with a spirit lamp?
- Decomposition of calcium carbonate to calcium oxide and carbon dioxide on heating is an example of ____.
- ________ is not a chemical change.
During the electrolysis of water, hydrogen and oxygen are released in which ratio?
When dilute Hydrochloric acid (HCl) reacts with Sodium Hydrogen Carbonate (NaHCO3), which is the product formed along with Sodium chloride (NaCl) and Water (H2O)?
Important Questions from Chemical Reaction
- Which one of the following is not an example of a redox reaction?
- Which one of the following is not a pigment?
- Which one of the following reactions is an example of decomposition reaction?
Match List I with List II and select the correct answer using the code given below the Lists:
LIST I
(Chemical process)
LIST II
(Reaction)
A.
Electrolysis of water
1.
Double displacement
reactionB.
Burning of coal
2.
Combination reaction
C.
Iron nail immersed in copper sulphate solution
3.
Decomposition reaction
D.
Addition of barium chloride solution to aluminium sulphate solution
4.
Displacement reaction
Consider the following reaction:
Fe2O3(s) + 2Al(s) → 2Fe(s) + Al2O3(s)
Which of the following statements about the given reaction is NOT correct?
