Litmus paper will turn blue when immersed in all of the following EXCEPT:

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11ecba2d_1238_320b_a3bf_a3bacad8328d_MD0008_00 Litmus paper is used as a pH indicator to determine whether a solution is acidic or basic. The paper is coated with litmus dye that changes color depending on the pH of the solution in which it is immersed. An acidic (pH < 7) solution will turn litmus paper red whereas a basic (pH > 7) solution will turn litmus paper blue. The Brønsted-Lowry definitions of acids and bases can be used to identify acidic and basic molecules. Brønsted-Lowry acids donate a proton (H⁺ ion), and Brønsted-Lowry bases accept a proton. The negatively charged ions OH⁻ and CN⁻ in Ca(OH)₂ and NaCN, respectively, can accept a proton (Choices A and D). The N atom in NH₃ (Choice B) has a lone pair of electrons, which can accept an H⁺ ion. Because these molecules are bases (proton acceptors), they will turn litmus paper blue. HNO₃ can donate a proton, making it an acid. Therefore, when litmus paper is immersed in HNO₃, it will turn red rather than blue. Educational objective: Litmus paper is used as an acid-base indicator and changes color depending on the pH of the solution it is in. Brønsted-Lowry acids (pH < 7) can donate a proton (H⁺ ion) and will turn litmus paper red. Brønsted-Lowry bases (pH > 7) can accept a proton and will turn litmus paper blue.

Litmus Paper Will Turn Blue When Immersed in All of the Following