Question

Write a balanced equation for each of the following reactions: (a) sodium reacts with water, (b) an aqueous solution of \(\mathrm{NaOH}\) reacts with \(\mathrm{CO}_{2},\) (c) solid \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) reacts with an \(\mathrm{HCl}\) solution, \((\mathrm{d})\) solid \(\mathrm{NaHCO}_{3}\) reacts with an \(\mathrm{HCl}\) solution, (e) solid \(\mathrm{NaHCO}_{3}\) is heated, (f) solid \(\mathrm{Na}_{2} \mathrm{CO}_{3}\) is heated.

Short answer

(a) \(2\text{Na} + 2\text{H}_2\text{O} \rightarrow 2\text{NaOH} + \text{H}_2\), (b) \(2\text{NaOH} + \text{CO}_2 \rightarrow \text{Na}_2\text{CO}_3 + \text{H}_2\text{O}\), (c) \(\text{Na}_2\text{CO}_3 + 2\text{HCl} \rightarrow 2\text{NaCl} + \text{CO}_2 + \text{H}_2\text{O}\), (d) \(\text{NaHCO}_3 + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O} + \text{CO}_2\), (e) \(2\text{NaHCO}_3 \rightarrow \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} + \text{CO}_2\), (f) No significant reaction.

Step-by-step solution

Reaction of Sodium with Water

The chemical reaction between sodium (Na) and water (H₂O) produces sodium hydroxide (NaOH) and hydrogen gas (H₂). The unbalanced equation is: \[ \text{Na} + \text{H}_2\text{O} \rightarrow \text{NaOH} + \text{H}_2 \]Balancing the equation:- On the left, we have 1 Na and 1 H₂O. - On the right, NaOH contributes 1 Na, 1 O, and 1 H; H₂ contributes 2 H. - Balance Na by ensuring there are 2 Na: \[ 2\text{Na} + 2\text{H}_2\text{O} \rightarrow 2\text{NaOH} + \text{H}_2 \]This balanced equation shows that two moles of sodium react with two moles of water to produce two moles of sodium hydroxide and one mole of hydrogen gas.

Reaction of NaOH and CO₂

When an aqueous solution of \(\text{NaOH}\) reacts with \(\text{CO}_2\), sodium carbonate \(\text{Na}_2\text{CO}_3\) and water \(\text{H}_2\text{O}\) are formed. The unbalanced equation is: \[ \text{NaOH} + \text{CO}_2 \rightarrow \text{Na}_2\text{CO}_3 + \text{H}_2\text{O}\]To balance the equation, consider:- Each NaOH supplies 1 Na and 1 O, and CO₂ supplies 1 C and 2 O.- Balance by ensuring 2 moles of NaOH are used:\[ 2\text{NaOH} + \text{CO}_2 \rightarrow \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} \]This shows the balance of all atoms, with 2 Na, 1 C, 4 O, and 2 H on both sides.

Reaction of Na₂CO₃ with HCl

Solid \(\text{Na}_2\text{CO}_3\) reacts with \(\text{HCl}\) to produce sodium chloride \(\text{NaCl}\), carbon dioxide \(\text{CO}_2\), and water \(\text{H}_2\text{O}\). The unbalanced equation is: \[ \text{Na}_2\text{CO}_3 + \text{HCl} \rightarrow \text{NaCl} + \text{CO}_2 + \text{H}_2\text{O} \]Balancing it requires:- \(\text{Na}_2\text{CO}_3\) supplies 2 Na, 1 C, and 3 O.- Ensure the use of 2 HCl moles: \[ \text{Na}_2\text{CO}_3 + 2\text{HCl} \rightarrow 2\text{NaCl} + \text{CO}_2 + \text{H}_2\text{O} \]This balances the equation with 2 Na, 2 Cl, 1 C, 3 O, and 2 H.

Reaction of NaHCO₃ with HCl

Solid \(\text{NaHCO}_3\) reacts with \(\text{HCl}\) to form sodium chloride \(\text{NaCl}\), water \(\text{H}_2\text{O}\), and carbon dioxide \(\text{CO}_2\). The unbalanced equation is: \[ \text{NaHCO}_3 + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O} + \text{CO}_2 \]Check the balance by examining each compound:- For every 1 \(\text{NaHCO}_3\), you need 1 \(\text{HCl}\) to maintain balance.Thus, the balanced equation remains: \[ \text{NaHCO}_3 + \text{HCl} \rightarrow \text{NaCl} + \text{H}_2\text{O} + \text{CO}_2 \]

Decomposition of NaHCO₃ upon Heating

When solid \(\text{NaHCO}_3\) is heated, it decomposes to form sodium carbonate \(\text{Na}_2\text{CO}_3\), water \(\text{H}_2\text{O}\), and carbon dioxide \(\text{CO}_2\). The unbalanced equation is: \[ \text{NaHCO}_3 \rightarrow \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} + \text{CO}_2 \]Balancing this requires recognition of the decomposition:- You need 2 \(\text{NaHCO}_3\) to form 1 \(\text{Na}_2\text{CO}_3\): \[ 2\text{NaHCO}_3 \rightarrow \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} + \text{CO}_2 \]This ensures that all atoms are balanced with 2 Na, 1 C, 5 O, and 2 H.

Decomposition of Na₂CO₃ upon Heating

Heating solid \(\text{Na}_2\text{CO}_3\) does not typically result in further decomposition under normal conditions. The heating would only be significant if considering further reactions like formation of sodium oxide \(\text{Na}_2\text{O}\) and carbon dioxide \(\text{CO}_2\) at very high temperatures not usually achievable in a simple heating scenario.

Key concepts

Sodium Reactions

When sodium (Na) meets water (H₂O), a fascinating and vigorous reaction occurs. This chemical interaction produces sodium hydroxide (NaOH) and hydrogen gas (H₂).

Here’s the balanced equation for this exciting transformation: \[ 2 \text{Na} + 2 \text{H}_2\text{O} \rightarrow 2 \text{NaOH} + \text{H}_2 \]

In this reaction, two moles of sodium react with two moles of water. This demonstrates the nature of chemical reactions, where products like gaseous hydrogen can form in quite spectacular ways, often with noticeable heat and fizzing.

When learning about these kinds of reactions, remember that sodium as a metal can be quite reactive, especially in the presence of moisture. Always consider safety and proper handling when observing such experiments.

NaOH and CO2 Reaction

The combination of an aqueous solution of sodium hydroxide \(\text{NaOH}\) with carbon dioxide \(\text{CO}_2\) results in the formation of sodium carbonate \(\text{Na}_2\text{CO}_3\) and water \(\text{H}_2\text{O}\). This showcases the ability of a base and an acidic oxide to produce a salt and water, commonly known as a neutralization reaction.

The balanced chemical equation for this reaction is:

\[ 2 \text{NaOH} + \text{CO}_2 \rightarrow \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} \]

In this equation, two moles of sodium hydroxide interact with one mole of carbon dioxide to produce one mole of sodium carbonate and one mole of water. This is an important reaction in understanding the transformation from simple molecules to more complex compounds.

What is remarkable in this reaction is the formation of sodium carbonate, which is a useful compound in various industrial processes, including glass-making and as an ingredient in detergents.

Na2CO3 and HCl Reaction

In this reaction, we observe a common acid-base reaction. Solid \( \text{Na}_2\text{CO}_3 \) reacts with hydrochloric acid \( \text{HCl} \) to produce sodium chloride \( \text{NaCl} \), carbon dioxide \( \text{CO}_2 \), and water \( \text{H}_2\text{O} \).

The balanced equation for this process is:
\[ \text{Na}_2\text{CO}_3 + 2\text{HCl} \rightarrow 2\text{NaCl} + \text{CO}_2 + \text{H}_2\text{O} \]

In the balanced equation, one mole of sodium carbonate combines with two moles of hydrochloric acid, resulting in the products mentioned. This kind of reaction is essential for neutralizing acidity, as well as releasing carbon dioxide gas. You can see a visible effervescence – the bubbling of \( \text{CO}_2 \) gas – during the reaction, which is a great visual indicator of the reaction proceeding.

Understanding such reactions highlights the changes involved in chemical processes and the proper balancing needed to account for all substances changing from reactants to products.

NaHCO3 Decomposition

When \( \text{NaHCO}_3 \), commonly known as baking soda, is decomposed by heating, it's a simple yet fascinating example of a chemical breakdown.

The balanced equation for this decomposition reaction is:
\[ 2\text{NaHCO}_3 \rightarrow \text{Na}_2\text{CO}_3 + \text{H}_2\text{O} + \text{CO}_2 \]

In this equation, two moles of sodium bicarbonate decompose to produce one mole of sodium carbonate, one mole of water, and one mole of carbon dioxide gas. This endothermic reaction absorbs heat.

What’s particularly interesting is watching \( \text{CO}_2 \) being released, which is a handy characteristic used in baking to leaven doughs and batters. It is also used in laboratory settings to study reaction kinetics and thermal decomposition processes. Experiments like these teach us how compounds change state, release gases, and how we can harness these reactions practically.