Advertisements
Advertisements
प्रश्न
Write equations for the reactions of calcium and potassium with water.
Advertisements
उत्तर
The reaction of calcium with water is exothermic, but the heat that evolved is not sufficient for the hydrogen to catch fire.
\[\ce{Ca_{(s)} + 2H2O_{(l)} -> Ca(OH)2_{(aq)} + H2_{(g)}}\]
Calcium starts floating because bubbles of hydrogen gas form and stick to the surface of the metal.
Potassium reacts violently with cold water, and its reaction is so violent and exothermic that the evolved hydrogen immediately catches fire.
\[\ce{2K_{(s)} + 2H2O_{(l)} -> 2KOH_{(aq)} + H2_{(g)}}\]
APPEARS IN
संबंधित प्रश्न
.................... liberated when acetic acid reacts with sodium metal.
(a) Hydrogen
(b) Chlorine
(c) Oxygen
(d) Nitrogen
Metal A has electronic configuration (2, 8, 1) and metal B has (2, 8, 8, 2). Which is more reactive? Why? Identify these metals.
Iron is
(a) More reactive than zinc
(b) More reactive than aluminium
(c) Less reactive than copper
(d) Less reactive than aluminium
Write the electron-dot structures for sodium, oxygen and magnesium.
Show the formation of Na2O by the transfer of electrons.
Differentiate between metal and non-metal on the basis of their chemical properties.
The reaction of an iron nail with copper sulphate solution is ........... reaction.
(a) Combination
(b) Displacement
(c) Double displacement
(d) Decomposition
Which of the two metals is more reactive: copper or silver?
Write equation for the reaction of sodium with oxygen.
What happens when magnesium reacts with very dilute nitric acid? Write an equation for the reaction involved.
Name another metal oxide which behaves like aluminium oxide.
Which non-metal has been placed in the reactivity series of metals?
An element X forms two oxides XO and XO2. The oxide XO is neutral but XO2 is acidic in nature. The element X is most likely to be:
(a) sulphur
(b) carbon
(c) calcium
(d) hydrogen
The elements whose oxides can turn litmus solution blue are:
(a) carbon and sulphur
(b) sodium and carbon
(c) potassium and magnesium
(d) magnesium and sulphur
An element E reacts with water to form a solution which turns phenolphthalein solution pink. The element E is most likely to be:
(a) S
(b) Ca
(c) C
(d) Ag
An element E forms an oxide E2O. An aqueous solution of E2O turns red litmus paper blue.
(a) What is the nature of the oxide E2O?
(b) State whether element E is a metal or a non-metal.
(c) Give one example of an element like E.
Which of the following reactions will not occur? Why not?
(a) MgSO4 (aq) + Cu (s) → CuSO4 (aq) + Mg (s)
(b) CuSO4 (aq) + Fe (s) → FeSO4 (aq) + Cu (s)
(c) MgSO4 (aq) + Fe (s) → FeSO4 (aq) + Mg (s)
Write the chemical equation for the following reaction:
Calcium metal reacts with water.
Write the chemical equation for the following reaction:
Manganese dioxide is heated with aluminum powder.
Metals are generally hard. Which of the following metals is an exception and can be cut with a knife?
