Question

Complete and balance the following equations: (a) $\mathrm{NaH}(s)+{\mathrm{H}}_2\mathrm{O}(l)⟶$ (b) $\mathrm{Fe}(s)+{\mathrm{H}}_2{\mathrm{SO}}_4(aq)⟶$ (c) ${\mathrm{H}}_2(g)+{\mathrm{Br}}_2(g)⟶$ (d) $\mathrm{Na}(l)+{\mathrm{H}}_2(g)⟶$ (e) $\mathrm{PbO}(s)+{\mathrm{H}}_2(g)⟶$

Short answer

The short answer for the given chemical reactions is as follows: (a) $\mathrm{NaH}(s)+{\mathrm{H}}_2\mathrm{O}(l)⟶\mathrm{NaOH}(s)+{\mathrm{H}}_2(g)$ (b) $\mathrm{Fe}(s)+{\mathrm{H}}_2{\mathrm{SO}}_4(aq)⟶{\mathrm{FeSO}}_4(s)+{\mathrm{H}}_2(g)$ (c) ${\mathrm{H}}_2(g)+{\mathrm{Br}}_2(g)⟶2\mathrm{HBr}(g)$ (d) $\mathrm{Na}(l)+{\mathrm{H}}_2(g)⟶\mathrm{NaH}(s)+{\mathrm{H}}_2(g)$ (e) $\mathrm{PbO}(s)+{\mathrm{H}}_2(g)⟶\mathrm{Pb}(s)+{\mathrm{H}}_2\mathrm{O}(l)$

Step-by-step solution

Identify the Reaction Type and Products

This reaction is an acid-base reaction where sodium hydride (NaH) acts as a strong base and water (H2O) acts as an acid. The reaction results in the formation of sodium hydroxide (NaOH) and hydrogen gas (H2).

Write the Unbalanced Equation

Now, let's write the products of the reaction: $$\mathrm{NaH}(s)+{\mathrm{H}}_2\mathrm{O}(l)⟶\mathrm{NaOH}(s)+{\mathrm{H}}_2(g)$$

Balance the Equation

Both sides of the equation already have equal numbers of atoms for each element (1 Na, 2 H, and 1 O). Therefore, the equation is balanced as written. #a) Balanced Equation#: $\mathrm{NaH}(s)+{\mathrm{H}}_2\mathrm{O}(l)⟶\mathrm{NaOH}(s)+{\mathrm{H}}_2(g)$ #b)# Complete and Balance the Equation: $\mathrm{Fe}(s)+{\mathrm{H}}_2{\mathrm{SO}}_4(aq)⟶$

Identify the Reaction Type and Products

This is a single replacement reaction where the metal (Fe) reacts with an acid (H2SO4). The reaction results in the formation of iron(II) sulfate (FeSO4) and hydrogen gas (H2).

Write the Unbalanced Equation

Now, let's write the products of the reaction: $$\mathrm{Fe}(s)+{\mathrm{H}}_2{\mathrm{SO}}_4(aq)⟶{\mathrm{FeSO}}_4(s)+{\mathrm{H}}_2(g)$$

Balance the Equation

Since there is only 1 atom of each element on both sides of the equation, it is already balanced. #b) Balanced Equation#: $\mathrm{Fe}(s)+{\mathrm{H}}_2{\mathrm{SO}}_4(aq)⟶{\mathrm{FeSO}}_4(s)+{\mathrm{H}}_2(g)$ #c)# Complete and Balance the Equation: ${\mathrm{H}}_2(g)+{\mathrm{Br}}_2(g)⟶$

Identify the Reaction Type and Products

This is a synthesis reaction where hydrogen gas (H2) and bromine gas (Br2) combine to form hydrogen bromide (HBr).

Write the Unbalanced Equation

Now, let's write the products of the reaction: $${\mathrm{H}}_2(g)+{\mathrm{Br}}_2(g)⟶\mathrm{HBr}(g)$$

Balance the Equation

To balance the equation, we need 2 HBr molecules on the product side: $${\mathrm{H}}_2(g)+{\mathrm{Br}}_2(g)⟶2\mathrm{HBr}(g)$$ #c) Balanced Equation#: ${\mathrm{H}}_2(g)+{\mathrm{Br}}_2(g)⟶2\mathrm{HBr}(g)$ #d)# Complete and Balance the Equation: $\mathrm{Na}(l)+{\mathrm{H}}_2(g)⟶$

Identify the Reaction Type and Products

This is a single replacement reaction where the metal sodium (Na) reacts with hydrogen gas (H2), leading to the formation of sodium hydride (NaH) and hydrogen gas (H2).

Write the Unbalanced Equation

Now, let's write the products of the reaction: $$\mathrm{Na}(l)+{\mathrm{H}}_2(g)⟶\mathrm{NaH}(s)+{\mathrm{H}}_2(g)$$

Balance the Equation

Both sides of the equation have equal numbers of atoms for each element, making the equation balanced as written. #d) Balanced Equation#: $\mathrm{Na}(l)+{\mathrm{H}}_2(g)⟶\mathrm{NaH}(s)+{\mathrm{H}}_2(g)$ #e)# Complete and Balance the Equation: $\mathrm{PbO}(s)+{\mathrm{H}}_2(g)⟶$

Identify the Reaction Type and Products

This is a single replacement reaction between a metal oxide (PbO) and hydrogen gas (H2). The reaction forms lead (Pb) and water (H2O).

Write the Unbalanced Equation

Now, let's write the products of the reaction: $$\mathrm{PbO}(s)+{\mathrm{H}}_2(g)⟶\mathrm{Pb}(s)+{\mathrm{H}}_2\mathrm{O}(l)$$

Balance the Equation

Both sides of the equation have equal numbers of atoms for each element, so the equation is balanced as written. #e) Balanced Equation#: $\mathrm{PbO}(s)+{\mathrm{H}}_2(g)⟶\mathrm{Pb}(s)+{\mathrm{H}}_2\mathrm{O}(l)$

Key concepts

Chemical Reactions

Chemical reactions are processes where substances known as reactants transform into different substances called products. During a reaction, molecules can break apart or combine to form new compounds. The reaction entails changes in the arrangement of atoms, which are generally accompanied by changes in energy.
A chemical reaction is often represented by a chemical equation which uses symbols and formulas to depict the starting materials (reactants) and the results (products).

Key elements of a chemical reaction include:

• Reactants: The starting substances that undergo a transformation.
• Products: The new substances formed as a result of a chemical reaction.
• Conservation of Mass: Mass cannot be created or destroyed in a chemical reaction, which is why equations need to be balanced.
• Types of Reactions: Different types such as synthesis, decomposition, single replacement, and double replacement.

Balancing a chemical equation is crucial because it reflects the conservation of mass by ensuring that the number of atoms of each element is the same on both sides of the equation.

Acid-Base Reaction

In an acid-base reaction, an acid reacts with a base to produce a salt and water. This kind of reaction is also known as neutralization. Acids are substances that donate hydrogen ions (H+), while bases accept hydrogen ions.
For example, when sodium hydride (NaH), a strong base, reacts with water (H2O), it results in the production of sodium hydroxide (NaOH) and hydrogen gas (H2).

Characteristics of acid-base reactions include:

• The formation of water (H2O) as one of the products.
• Production of a salt, which often is formed from the cation of the base and the anion of the acid.
• Change in pH: Neutralization moves the pH towards 7.

This type of reaction is essential in many chemical processes, including industrial applications and biological systems.

Synthesis Reaction

A synthesis reaction is a type of chemical reaction where two or more simple substances combine to form a more complex compound. It can be represented in its most basic form as A + B → AB.
A classic example of a synthesis reaction is the reaction between hydrogen gas (H2) and bromine gas (Br2) to form hydrogen bromide (HBr).

Understanding synthesis reactions includes:

• Combination: Two or more reactants form a single product.
• Energy: These reactions often release energy, although some require an input of energy.
• Simplicity: They usually involve simpler reactants joining to form a more complex substance.

Synthesis reactions are essential in various industrial processes, including the creation of new compounds used in products and materials.

Single Replacement Reaction

In a single replacement reaction, one element replaces a similar element in a compound. This typically involves metals and non-metals swapping places in a compound.
For instance, when iron (Fe) reacts with sulfuric acid (H2SO4), iron replaces hydrogen, resulting in iron(II) sulfate (FeSO4) and hydrogen gas (H2).

Essential points about single replacement reactions:

• Reactivity Series: The more reactive metal (or non-metal) displaces the less reactive one.
• Product Formation: A new compound is produced along with an element in free form.
• Real-world Application: Often used in metal extraction and other industrial processes.

These reactions are a fundamental part of chemistry involving the reactivity and interaction of different elements within compounds.