Question

2. Differentiate between the Reaction of magnesium and calcium with water.
Write the equation of the chemical reaction involved.
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Answer 1

Answer:

Calcium is more reactive than magnesium. Calcium reacts with water to form calcium hydroxide and hydrogen gas. On the other hand, magnesium does not react with cold water but reacts with hot water to form magnesium hydroxide and hydrogen gas.

Ca + 2H2O = Ca(OH)2 + H2

Mg + 2H2O = Mg(OH)2 + H2

Explanation:

Answer 2

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We need to differentiate between the Reaction of Magnesium and Calcium with water. Taking reference from the Reactivity Series , we see that , Magnesium is located below Calcium .

$\boxed{\begin{array}{c|c}\underline{\red{\sf Element }} &\underline{\red{\sf Symbol}} \\ \\ \sf Potasium & \sf K \\\\\sf Sodium &\sf Na \\\\\sf Calcium &\sf Ca \\\\\sf Magnesium & \sf Mg \end{array}}$

Therefore , Calcium reacts easily with cold water , but Magnesium doesn't reacts with cold water. It reacts with hot water . The Reaction of calcium with water is ,

$\qquad\dashrightarrow\boxed{\sf Ca +2H_2O \to Ca(OH)_2 + H_2 }$

The Reaction of Magnesium is ,

$\qquad\dashrightarrow\boxed{\sf Mg +2H_2O \to Mg(OH)_2 + H_2 }$

$\underline{\underline{\blacksquare\pink{\sf \:\: Reason \ behind \ that :- }}}$

Magnesium and Calcium both have 2 electrons in their valence shell. Both of them are placed in same group in the perodic table. The electronic configuration of Mg is 2,8,2 and that of Ca is 2,8,8,2 .

• Thus , an extra shell is present in Calcium , so its valence electrons are far from nuclues as compared to Magnesium. Therefore , the nuclear force of attraction between the valence shell and nuclues is more in Magnesium than Calcium.
• So its easy to remove the two valence electrons in Calcium even with cold water . But in magnesium extra energy is required and that energy is provided by the hot water .
• Hence , magnesium reacts with hot water or steam but not with cold water. Whereas Calcium can react with all the three kinds .

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