Question

When aqueous solutions of sodium chloride, \(\mathrm{NaCl}\) and silver nitrate, \(\mathrm{AgNO}_{3}\), are mixed, a precipitate forms, but this precipitate is not sodium nitrate. What does this reaction tell you about the solubility of \(\mathrm{NaNO}_{3}\) in water?

Short answer

The balanced chemical equation for the reaction between NaCl and AgNO₃ is given by: \[ \ce{NaCl_{(aq)} + AgNO3_{(aq)} -> NaNO3_{(aq)} + AgCl_{(s)}} \] The precipitate formed is silver chloride (AgCl), which is insoluble in water. However, sodium nitrate (NaNO₃) is formed as an aqueous solution, indicating that it is soluble in water.

Step-by-step solution

Write down the initial reactants

In this reaction, we have two reactants – an aqueous solution of sodium chloride (NaCl) and an aqueous solution of silver nitrate (AgNO3).

Identify the possible products

In double displacement reactions like this, the possible products are formed by exchanging the cations and anions of the reactants. So, the possible products would be sodium nitrate (NaNO3) and silver chloride (AgCl).

Write down the balanced chemical equation

Now that we've identified the possible products, we can write down the balanced chemical equation for this reaction: \[ \ce{NaCl_{(aq)} + AgNO3_{(aq)} -> NaNO3_{(aq)} + AgCl_{(s)}} \] The equation tells us that when NaCl and AgNO3 are mixed in an aqueous solution, NaNO3 and AgCl are formed as products. Here, the precipitate mentioned in the problem is silver chloride (AgCl), indicated by the (s) notation, which means it is insoluble in water.

Analyze solubility of NaNO3

From the balanced chemical equation, we see that sodium nitrate (NaNO3) is formed as an aqueous solution, indicated by the (aq) notation, which means it is soluble in water. So, the reaction tells us that NaNO3 is soluble in water.

Key concepts

Precipitation Reaction

In chemistry, a precipitation reaction occurs when two solutions are mixed and an insoluble solid, known as a precipitate, forms and falls out of the solution. This type of reaction is a hallmark of solubility challenges between different ionic compounds.
For instance, when you mix aqueous solutions of sodium chloride (\(\mathrm{NaCl}\)) and silver nitrate (\(\mathrm{AgNO}_{3}\)), a precipitate of silver chloride (\(\mathrm{AgCl}\)) is formed.

• This happens because silver chloride is insoluble in water.
• Hence, it separates out as a solid.

The formation of a precipitate like silver chloride serves as a visual indicator of a chemical change taking place. Not all combination of reactants lead to precipitation reactions; it specifically depends on the solubility of the products in the given solvent, usually water.

Double Displacement Reaction

Double displacement reactions are chemical reactions where two compounds exchange parts with each other to form two new compounds. Also known as metathesis reactions, they are essential for understanding the basics of chemical reactivity in solution.
These reactions follow the general form:\[\text{AB} + \text{CD} \rightarrow \text{AD} + \text{CB}\]For the reaction between sodium chloride and silver nitrate:

• The sodium (Na⁺) switches places with the silver (Ag⁺), and chloride (Cl⁻) exchanges with nitrate (NO₃⁻).
• This results in the formation of sodium nitrate (\(\mathrm{NaNO}_{3}\)) and silver chloride (\(\mathrm{AgCl}\)).

This exchange showcases the dynamic nature of ionic interactions in solution and often leads to the formation of a precipitate, such as silver chloride in this case.

Chemical Equation Balancing

Balancing chemical equations is a fundamental skill in chemistry that ensures the law of conservation of mass is obeyed. This law states that matter cannot be created or destroyed in an isolated system. In a balanced equation, the number of atoms for each element is the same on both sides of the equation.
For example, in the reaction between sodium chloride and silver nitrate:\[\ce{NaCl_{(aq)} + AgNO3_{(aq)} -> NaNO3_{(aq)} + AgCl_{(s)}}\]The equation is already balanced, indicating:

• One Na atom on both sides of the equation.
• One Cl and one Ag atom, respectively, on each side.
• One NO₃ group on both sides as well.

Ensuring balance helps accurately represent the reaction and provides insight into the amounts of reactants required and products formed.

Aqueous Solutions

Aqueous solutions are solutions where water is the solvent. These are a common pathway for many chemical reactions, including precipitation and double displacement reactions. When a compound is labeled with \((aq)\), it indicates the substance is dissolved in water, creating a homogenous mixture.
An aqueous solution of sodium chloride and an aqueous solution of silver nitrate were used in the discussed precipitation reaction.

• Solubility data shows that sodium nitrate (\(\mathrm{NaNO}_{3}\)) remains in solution, marked by the \((aq)\) notation.
• Silver chloride's lack of \((aq)\) confirms its solid state, indicating insolubility.

Through studying aqueous solutions, we gain deeper understanding of the solubility rules function and how ionic compounds behave in water.