Question

If a patient experiencing digestive problems needs a series of gastrointestinal X rays taken, they frequently must drink what is called a "barium cocktail." It consists of a thick suspension of barium sulfate in water, which is used because barium sulfate is opaque to \(X\) rays, and the thick suspension coats the walls of the digestive tract and makes them more visible on the X rays. Barium sulfate may be prepared in the laboratory by mixing a solution of barium chloride with a solution of sodium sulfate, which produces solid barium sulfate suspended in a solution of sodium chloride. Write the unbalanced chemical equation for this process.

Short answer

The balanced chemical equation for the preparation of barium sulfate from barium chloride and sodium sulfate is: \(BaCl_2 (aq) + Na_2SO_4 (aq) \rightarrow BaSO_4 (s) + 2 NaCl (aq)\)

Step-by-step solution

Identify the reactants

The reactants in this chemical process are barium chloride and sodium sulfate. Their chemical formulas are BaCl2 and Na2SO4, respectively.

Identify the products

The products of this reaction are solid barium sulfate and sodium chloride in solution. The chemical formulas for these are BaSO4 (solid) and NaCl (aqueous).

Write the unbalanced chemical equation

Now we can write the unbalanced chemical equation using the reactants and products: BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (s) + NaCl (aq) Note that the equation is currently unbalanced. We need an equal number of each type of atom on both sides of the equation.

Balance the chemical equation

We can balance the equation by adjusting the coefficients in front of each compound. In this case, we need to add a coefficient of 2 in front of NaCl, because there are two sodium and two chloride atoms in the reactants: BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2 NaCl (aq) Now the equation is balanced, with the same number of atoms for each element on both sides of the equation.

Key concepts

Chemical Reaction

When we talk about a chemical reaction, we're referring to the process in which substances, known as reactants, transform into new substances, called products. This transformation happens through the breaking and forming of chemical bonds, leading to a change in the composition and properties of the matter involved.

Take the barium cocktail as an example. The patient's gastrointestinal issue prompts the use of a substance that can highlight areas during an X-ray. This substance is the product of a chemical reaction between barium chloride (BaCl2) and sodium sulfate (Na2SO4), where they form a precipitate of barium sulfate (BaSO4) and a solution of sodium chloride (NaCl). During the reaction, each reactant undergoes a change at the molecular level, resulting in the production of these new substances with different physical and chemical properties than the original reactants.

Understanding chemical reactions is fundamental to the field of chemistry, as they are the basis for creating new materials, pharmaceuticals, and even the food we eat. The ability to predict the outcomes of these reactions is a critical skill for scientists and students alike.

Stoichiometry

Stoichiometry is a section of chemistry that deals with the quantitative relationships between reactants and products in a chemical reaction. It is essentially the 'recipe' for a chemical process. With stoichiometry, students can calculate the amounts of substances required or produced in a reaction.

In the context of the barium cocktail, stoichiometry is used to balance the chemical equation. Balancing is crucial because matter cannot be created or destroyed in a chemical reaction (Law of Conservation of Mass). To make sure we respect this law, we must have the same number of each type of atom on both sides of the equation. What this means for our barium cocktail is that the amounts of barium, chloride, sodium, and sulfate ions before and after the reaction must remain constant. The act of balancing the equation, like adding the coefficient of 2 in front of NaCl in the final step, ensures that this condition is met.

Stoichiometry is not just an academic exercise but has real-world applications. In pharmaceutical manufacturing, for example, precise stoichiometry is crucial to ensure the correct dosage of a drug's active ingredients. In environmental science, stoichiometry can help us understand the chemical reactions that occur in our atmosphere and natural water bodies.

Precipitation Reaction

A precipitation reaction is a type of chemical reaction where two solutions containing soluble salts combine to form one or more insoluble products, known as precipitates. These precipitates are solids that separate from the reaction mixture. Precipitation reactions are used in various ways, including to remove unwanted ions from a solution, to purify products, and even in medical applications like the creation of the barium cocktail.

The reaction between barium chloride and sodium sulfate is a classic example of a precipitation reaction. When mixed, they produce the solid barium sulfate suspended in water and a secondary product, a solution of sodium chloride. The insoluble barium sulfate is the substance that makes the barium cocktail opaque to X-rays, which in turn highlights the walls of the digestive tract on the images.

Identifying a precipitation reaction requires knowledge of the solubility rules - guidelines that help predict whether a salt will dissolve in water. These rules are taught early in chemistry education and are vital for understanding reactions like the one used to create barium sulfate. The practical applications of such reactions are abundant, demonstrating the importance of precipitation reactions in everyday life and technological processes.