Question

which of the following chemical equations shows the formation of sodium hydroxide (naoh) and hydrogen gas (h₂) from the reaction of solid sodium (na) with water (h₂o)?
a 2na + 2h₂o → 2naoh + 2h
b 2na + 2h₂o → 2naoh + h₂
c 2naoh + h₂ → 2na + 2h₂o
d 2naoh + 2h₂o → 2na + 2h

Explanation:

Step1: Analyze the reactants and products

The reaction is between solid sodium (Na) and water (H₂O). The products should be sodium hydroxide (NaOH) and hydrogen gas (H₂).

Step2: Check the law of conservation of mass

• Option a: \(2Na + 2H_2O

ightarrow2NaOH + 2H\) is incorrect because hydrogen should be \(H_2\) not \(H\).

• Option b: \(2Na+2H_2O

ightarrow2NaOH + H_2\) is correct. Sodium reacts with water to form sodium hydroxide and hydrogen gas. The number of atoms of each element (Na: 2, H: 4, O: 2) is the same on both sides of the equation.

• Option c: \(2NaOH + H_2

ightarrow2Na + 2H_2O\) is a reverse reaction of what is required.

• Option d: \(2NaOH+2H_2O

ightarrow2Na + 2H\) has incorrect reactants and wrong formula for hydrogen.

Answer:

B. \(2Na + 2H_2O
ightarrow2NaOH + H_2\)