Question 1: Define what a sulfate ion is and write its chemical formula.

Answer: A sulfate ion is a polyatomic ion with the chemical formula SO4^{2-}.

Question 2: Explain the principle behind testing for sulfate ions using barium chloride solution.

Answer: Barium chloride reacts with sulfate ions to form insoluble barium sulfate, which appears as a white precipitate, indicating the presence of sulfate.

Question 1: A forensic sample contains 0.05 mol of sulfate ions. How many grams of barium sulfate (BaSO4) would be formed if all sulfate reacts?

Answer: BaSO4 molar mass = 137.33 (Ba) + 32.07 (S) + 4×16.00 (O) = 233.39 g/mol. Mass = 0.05 mol × 233.39 g/mol = 11.67 grams.

Question 1: Describe the steps involved in testing a powdered sample for the presence of sulfate ions using barium chloride solution.

Answer: First, dissolve a small amount of the powdered sample in distilled water. Then, add a few drops of dilute hydrochloric acid to eliminate any carbonate ions. Next, add barium chloride solution to the sample. If a white precipitate forms, sulfate ions are present. The precipitate can be filtered and washed for further analysis.

Question 2: Identify at least two safety precautions that should be taken when conducting sulfate tests in a forensic laboratory.

Answer: Wear gloves and safety goggles to protect skin and eyes from chemicals; handle acids and barium compounds in a well-ventilated area to avoid inhalation of fumes.

Question 1: A forensic sample from a crime scene reacts with barium chloride to produce a white precipitate. The precipitate is filtered, dried, and weighs 2.5 grams. If the precipitate is pure BaSO4, estimate the amount of sulfate ions originally present in the sample.

Answer: Moles of BaSO4 = 2.5 g / 233.39 g/mol ≈ 0.0107 mol. Since each sulfate ion forms one BaSO4, the sample contained approximately 0.0107 mol of sulfate ions.

Question 1: Explain how sulfate testing can be used in forensic investigations to identify substances found at a crime scene.

Answer: Sulfate testing helps forensic scientists identify specific chemical substances by detecting the presence of sulfate ions. For example, it can confirm the presence of certain minerals or compounds in powders, liquids, or residues. The formation of a white precipitate of barium sulfate indicates sulfate ions, which can be linked to particular materials or substances involved in a crime, aiding in evidence analysis.

Question 2: Which industry heavily relies on sulfate detection for quality control, and how does this process benefit the industry?

Answer: Water treatment