Question

Complete the following chemical equations a. \(\mathrm{Na}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(1) \rightarrow\) b. \(\mathrm{K}(\mathrm{s})+\mathrm{H}_{2} \mathrm{O}(1) \rightarrow\)

Short answer

The short answers for the complete chemical equations are: a. \(Na(s) + H_{2}O(l) \rightarrow NaOH + H_{2}\) b. \(2K(s) + 2H_{2}O(l) \rightarrow 2KOH + H_{2}\)

Step-by-step solution

Identify the products

In both cases, the alkali metals (sodium and potassium) will react with water, producing a metal hydroxide and hydrogen gas. For Sodium: NaOH (sodium hydroxide) and H2 (hydrogen gas) For Potassium: KOH (potassium hydroxide) and H2 (hydrogen gas)

Write unbalanced equations

Now that we know the products, let's write the unbalanced chemical equations: a. Na(s) + H2O(l)→ NaOH + H2 b. K(s) + H2O(l)→ KOH + H2

Balance the equations

Finally, we must ensure that the number of atoms for each element is the same on both sides of the arrow. a. The equation Na(s) + H2O(l)→ NaOH + H2 is already balanced because there is 1 Na atom, 2 H atoms, and 1 O atom on both sides of the reaction. b. For K(s) + H2O(l)→ KOH + H2, we need to balance the number of hydrogen atoms, as there are 3 H atoms on the left side of the equation but only 2 on the right. To balance this equation, we will need to add another mole of KOH and K. The balanced equation is: 2K(s) + 2H2O(l) → 2KOH + H2 So, the completed chemical equations are: a. Na(s) + H2O(l) → NaOH + H2 b. 2K(s) + 2H2O(l) → 2KOH + H2

Key concepts

Sodium and Water Reaction

When sodium (Na) comes into contact with water (H_2O), a vigorous chemical reaction occurs. Sodium is an alkali metal, which are known for their reactivity, especially with water. The reaction is characterized by the formation of sodium hydroxide (NaOH) and hydrogen gas (H_2). Let's break it down further:

• Metal hydroxide formation: Sodium reacts swiftly with water to form sodium hydroxide. This compound is a strong base, which is commonly used in various applications, including soap production.
• Hydrogen gas release: The reaction also produces hydrogen gas, a flammable substance, which can ignite due to the heat of the reaction, sometimes resulting in a small explosion.

The balanced chemical equation for this reaction is:\[\mathrm{Na} (\mathrm{s}) + \mathrm{H}_2 \mathrm{O} (\mathrm{l}) \rightarrow \mathrm{NaOH} (\mathrm{aq}) + \mathrm{H}_2 (\mathrm{g})\]This reaction showcases the reactive nature of alkali metals with water.

Potassium and Water Reaction

Potassium (K) is another highly reactive alkali metal, similar to sodium, and it also reacts vigorously with water. The reaction follows a similar pattern to that of sodium:

• Potassium hydroxide production: Potassium reacts with water to form potassium hydroxide (KOH), another strong base used in cleaning products and other applications.
• Hydrogen gas evolution: Just like the sodium reaction, hydrogen gas is released, which can ignite due to the heat generated from the reaction.

The balanced equation for this reaction is:\[2 \mathrm{K} (\mathrm{s}) + 2 \mathrm{H}_2 \mathrm{O} (\mathrm{l}) \rightarrow 2 \mathrm{KOH} (\mathrm{aq}) + \mathrm{H}_2 (\mathrm{g})\]Due to the high reactivity of potassium with water, the reaction is more intense and exothermic compared to sodium. This means it releases more energy, which can lead to more vigorous releases of hydrogen gas.

Alkali Metals

Alkali metals belong to Group 1 of the periodic table and include lithium, sodium, potassium, rubidium, cesium, and francium. These metals share several key properties:

• Reactivity: Alkali metals are very reactive, especially with water and oxygen, because they have one electron in their outermost shell, making them eager to lose that electron and achieve a stable electron configuration.
• Softness: They are typically soft and can be cut with a knife. The softness increases as you move down the group.
• Low density: These metals have lower densities than most other metals. In fact, lithium, sodium, and potassium can float on water.
• Color and Appearance: They appear shiny when freshly cut, but tarnish quickly when exposed to air due to oxidation.

Understanding these properties helps predict and explain the vigorous reactions alkali metals exhibit, particularly when introduced to water.

Chemical Reactions in Chemistry

Chemical reactions are processes in which substances combine or break apart to form new substances. These reactions are fundamental to chemistry and can be classified based on several characteristics:

• Types of reactions: Reactions can be categorized into types such as synthesis, decomposition, single replacement, double replacement, and combustion. The reactions of sodium and potassium with water are examples of single replacement reactions, where one element replaces another in a compound.
• Balanced equations: A chemical equation must be balanced, meaning the number of atoms for each element is the same on both sides. This obeys the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction.
• Reactivity: Reactivity is a crucial concept that indicates how easily a substance undergoes a chemical change. For alkali metals, this involves losing their outer electron.

Understanding chemical reactions is essential for predicting the outcomes of these reactions and their practical applications in everyday life. For instance, balancing equations not only helps in academic exercises but also in industrial applications where precise chemical formulations are required.