Problem 79 - Introductory Chemistry Atoms First

Question

Sodium chloride reacts with bromine gas, \(\mathrm{Br}_{2}\), to produce sodium bromide plus chlorine gas. Write a balanced equation for this reaction.

Step-by-Step Solution

Answer

The balanced chemical equation for the reaction of sodium chloride with bromine gas is: \(2 \mathrm{NaCl} + \mathrm{Br}_{2} \rightarrow 2 \mathrm{NaBr} + \mathrm{Cl}_{2}\).

Step 1: Identify the reactants and products

The reactants in this reaction are sodium chloride (NaCl) and bromine gas (Br₂). The products are sodium bromide (NaBr) and chlorine gas (Cl₂).

Step 2: Write the unbalanced chemical equation

Place the reactants on the left-hand side and the products on the right-hand side, separated by an arrow. NaCl + Br₂ → NaBr + Cl₂

Step 3: Balance the chemical equation

Check the number of atoms for each element on both sides of the equation. Then, adjust the coefficients to balance the equation. Na: 1 atom on the left, 1 atom on the right - balanced Cl: 1 atom on the left, 2 atoms on the right - not balanced Br: 2 atoms on the left, 1 atom on the right - not balanced To balance chlorine, we can add a coefficient of 2 in front of NaCl: 2NaCl + Br₂ → NaBr + Cl₂ Now, we have 2 Cl atoms on both sides. However, now we have 2 Na atoms on the left side, so we need to adjust the coefficient for NaBr as well: 2NaCl + Br₂ → 2NaBr + Cl₂ Finally, let's check the balance again: Na: 2 atoms on the left, 2 atoms on the right - balanced Cl: 2 atoms on the left, 2 atoms on the right - balanced Br: 2 atoms on the left, 2 atoms on the right - balanced

Step 4: Write the balanced chemical equation

The balanced chemical equation for the reaction of sodium chloride with bromine gas is: 2NaCl + Br₂ → 2NaBr + Cl₂

Key Concepts

Chemical Reactions

Chemical reactions are processes where reactants are transformed into products. These transformations involve the breaking and forming of chemical bonds, resulting in the rearrangement of atoms.
In a chemical equation, the substances you start with, called the reactants, are placed on the left side. You then see an arrow (\(\rightarrow\)), which points to the substances formed called products, listed on the right.

• The equation symbolizes the changes happening in a reaction.
• It's like a recipe showing how ingredients change into a final dish.

Writing and balancing chemical equations help us understand how much of each substance is involved. This ensures the conservation of mass, a key principle stating that atoms are neither created nor destroyed in a chemical reaction.

Reactants and Products

In any chemical reaction, reactants are the starting materials, while products are the end result. Identifying these is crucial for understanding and balancing chemical equations.

• Reactants are the ingredients mixed together to provoke a chemical change. In our exercise, sodium chloride (NaCl) and bromine gas (Br₂) were the reactants.
• Products are the new chemicals produced by this change. For the exercise, sodium bromide (NaBr) and chlorine gas (Cl₂) were the products.

The job of balancing a chemical equation is to ensure that the number of each type of atom is the same on both sides. This represents how each reactant particle transitions to a product without any loss of mass.

Sodium Compounds

Sodium compounds are vital in many chemical reactions. Sodium, a silvery-white metal, is highly reactive and often combines with other elements.

• Sodium chloride (NaCl) is a common compound, also known as table salt. In reactions, it often serves as an excellent source of sodium ions.
• In the exercise, \(\text{NaCl}\) reacted with \(\text{Br}_2\) to produce sodium bromide (\(\text{NaBr}\)), a compound similar in structure to NaCl but containing bromine instead of chlorine.

Sodium compounds are essential in everyday life, from table salt to medications and other industrial products. Their reactivity makes them highly significant in chemical labs and industries.

Halogen Displacement Reactions

Halogen displacement reactions involve a more reactive halogen replacing a less reactive one in a compound. This is a type of single displacement reaction commonly encountered in chemistry.

• In the exercise, bromine (\(\text{Br}_2\)) displaced chlorine (Cl) in sodium chloride to form sodium bromide.
• This reaction happens because bromine is more reactive than chlorine, making it capable of "kicking out" the chlorine from the compound.

Understanding the reactivity of halogens is essential. They are a group of elements found in Group 17 of the periodic table, known for their high reactivity.
The order of reactivity usually goes from fluorine (most reactive) to iodine (least reactive), influencing how these reactions occur. In displacement reactions, more reactive halogens will naturally replace less reactive ones, demonstrating the principles of chemical hierarchy and reactivity.