Question

Directions: Each question contains Statement- 1 and Statement- 2 and has the following choices (a), (b), (c) and (d), out of which ONLY ONE is correct. (a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1 (b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is NOT a correct explanation for Statement- 1 (c) Statement- 1 is True, Statement- 2 is False (d) Statement- 1 is False, Statement- 2 is True Statement 1 Formic acid produces a white precipitate with \(\mathrm{HgCl}_{2}\). and Statement 2 Mercuric salt of formic acid is insoluble and therefore gets precipitated.

Short answer

Question: Determine the truth of the statements and the correct explanation option: Statement 1: Formic acid produces a white precipitate when it reacts with \(\mathrm{HgCl}_{2}\). Statement 2: The mercuric salt of formic acid is insoluble and therefore gets precipitated. a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1 b) Statement- 1 is True, Statement- 2 is True; Statement- 2 is not a correct explanation for Statement- 1 c) Statement- 1 is False, Statement- 2 is True d) Statement- 1 is True, Statement- 2 is False Answer: a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1

Step-by-step solution

Analyzing Statement 1

Statement 1 states that formic acid produces a white precipitate when it reacts with \(\mathrm{HgCl}_{2}\). To determine if this is true or false, let's take a look at the reaction between formic acid (HCOOH) and mercuric chloride (\(\mathrm{HgCl}_{2}\)): $$\mathrm{ HCOOH + HgCl_2 \rightarrow Hg(HCOO)_2 + 2HCl}$$ In this reaction, Hg(HCOO)\(_2\) is formed, which is a white precipitate. So, Statement 1 is true.

Analyzing Statement 2

Statement 2 states that the mercuric salt of formic acid is insoluble and therefore gets precipitated. To analyze the solubility of the mercuric salt of formic acid (Hg(HCOO)\(_2\)), we need to look at its solubility product constant (Ksp). Unfortunately, the value for Ksp is not readily available. But, it is a general rule that the salts of weak acids and strong metals are usually insoluble. In our case, formic acid is a weak acid, and mercury is a strong metal. Thus, we can conclude that the mercuric salt of formic acid (Hg(HCOO)\(_2\)) is likely insoluble, which is why the white precipitate is formed. So, Statement 2 is also true.

Analyzing the relationship between Statement 1 and Statement 2

Statement 1 tells us that a white precipitate is formed when formic acid reacts with \(\mathrm{HgCl}_{2}\). Statement 2 explains the reason for this precipitate being formed - the insolubility of the mercuric salt of formic acid. Therefore, we can say that Statement 2 is a correct explanation for Statement 1. Now, as both statements are true and Statement 2 is a correct explanation for Statement 1, the final answer is: (a) Statement- 1 is True, Statement- 2 is True; Statement- 2 is a correct explanation for Statement- 1

Key concepts

Formic Acid Reaction

Formic acid, also known as methanoic acid, is the simplest carboxylic acid and has the chemical formula HCOOH. In a reaction, formic acid can engage with various chemicals to form salts, esters, and even cause reduction reactions due to its somewhat unique structure that includes both a carboxyl group and a hydrogen atom bonded to the carbonyl carbon.

When formic acid reacts with mercuric chloride (HgCl₂), a chemical reaction occurs resulting in the formation of mercuric formate (Hg(HCOO)₂) and hydrochloric acid (HCl). Mercuric formate precipitates out as a white solid when its concentration exceeds its solubility in the solution. This is a common type of reaction in organic chemistry where a weak acid like formic acid reacts with a metal chloride, leading to the formation of a salt and an acid.

Mercuric Chloride Precipitate

Mercuric chloride precipitate occurs when solutions of mercury(II) chloride (HgCl₂) react with certain substances that lead to the formation of an insoluble product. In the context of the reaction with formic acid, the product is mercuric formate (Hg(HCOO)₂), which is not soluble in water and hence precipitates out as a solid.

Mercury compounds are known to form precipitates with various anions, and this property is exploited in both qualitative and quantitative chemical analysis. When dealing with mercuric chloride precipitates, caution must be taken due to the toxicity of mercury compounds. Laboratory safety protocols dictate the use of gloves and proper disposal of mercury-containing waste.

Solubility Product Constant

The solubility product constant (Ksp) is an equilibrium constant that applies to the dissolution of a slightly soluble ionic compound. It quantitatively measures the product of the concentrations of the ions that are produced when the compound dissolves, each raised to the power of its coefficient in the dissolution equation.

The solubility product is particularly useful for predicting whether a precipitate will form in a solution. A low Ksp value indicates that the compound is less soluble. When the product of the ion concentrations in a solution exceeds the Ksp, a precipitate forms. This principal is pivotal in the context of mercuric formate in our original exercise, where its low solubility leads to the formation of the observed white precipitate.

Salts of Weak Acids

When a weak acid, such as formic acid, reacts with a strong metal ion, it often forms a salt that has limited solubility in water. Salts of weak acids can undergo hydrolysis, a reaction with water, which can impart acidic or basic properties to the solution, depending on the nature of the ions involved.

In the case of a weak acid like formic acid, the anion (formate ion) has a tendency to bind strongly with certain metal ions, like mercury, to form an insoluble compound. The low solubility of these salts is attributed to the strong ionic interactions in the solid state, which makes it difficult for the ions to break apart and dissolve in water. Chemical equilibria involving these salts are an important part of many systems, including biological, environmental, and industrial processes.