Final answer:
Na2S2O3 (Sulfite) acts as a reducing agent in chemical reactions.
This correct answer is a.
Step-by-step explanation:
Sodium thiosulfate (Na2S2O3) is commonly known as a reducing agent. In chemical reactions, a reducing agent is a substance that donates electrons, leading to the reduction (gain of electrons) of another substance.
Sodium thiosulfate is often used as a reducing agent in various applications, including:
Photography: In photographic processing, sodium thiosulfate is used as a fixing agent to remove unexposed silver halide from photographic films and papers.
During this process, sodium thiosulfate reduces the silver halide to soluble silver complexes, allowing them to be washed away.
Water Treatment: Sodium thiosulfate is used to dechlorinate tap water before it is released into aquatic environments. It reacts with chlorine, effectively reducing it to chloride ions. This process is crucial in preventing harm to aquatic life.
Analytical Chemistry: Sodium thiosulfate is employed in titration methods as a reducing agent to determine the concentration of certain analytes, such as iodine.
It can react with iodine to form iodide ions, changing the color of the solution and allowing for the endpoint detection of the titration.
In these applications, sodium thiosulfate facilitates reduction reactions by donating electrons, making it a useful reducing agent in various chemical processes.
This correct answer is a.