Question

Giving chemical equation say what happens when
a) Zinc reacts with dilute HCl.
b) Sodium (Na) reacts with water.
c) Aluminium reacts with sodium hydroxide.​

Answer 1

1. Question⇒    Giving chemical equation say what happens when
2. a) Zinc reacts with dilute HCl.
3. b) Sodium (Na) reacts with water.  
4. c) Aluminium reacts with sodium hydroxide.​

Explanation:

1. zinc is a metal hence when it will react with hydrochloric acid, it will form the salt Zinc Chloride which is a soluble salt while hydrogen gas is also given off which can be tested by bringing lighted splint near it which will extinguish with a “pop” sound indicating that hydrogen was present.

• Zn plus 2HCl —-> ZnCl2 plus H2                                                                                               ⇒2. balanced equation is
• 2Na + 2H2O →2NaOH + H2
• water reacts with sodium metal to give sodium hydroxide and hydrogen. It is double replacement reaction.                                                 ⇒3. Al will react with aqueous NaOH to give Sodium Aluminate with rapid evolution of H2 gas.
• 2 Al + 2 NaOH + 2 H2O → 2 NaAlO2 + 3 H2
• But this is just the theoretical way to write the reaction. In aqueous reaction conditions NaAlO2 will be accompanied by 2H2O i.e. “NaAlO2.2H2O”.
• This actually exists as Al[OH4]- ions i.e. Sodium tetrahydroxoaluminate(III) ions. Thus the reaction will be -
• 2Al (s) + 2NaOH(aq) + 6H2O(l) → 2 Na+ [Al(OH)4] –(aq) + 3H2(g)  
• Even going further -  
• The structure of [Al(OH)4] – is complicated than it appears to be. Its structure changes with both pH and concentration.