Answer to Question #344675 in General Chemistry for Salven

Question

Which compound when dissolved in water will turn blue litmus paper red?

a. H2O (l)

b. BaCI2 (aq)

c. HClO (aq)

d. NH4OH (aq)

Answer 1

Litmus paper is an indicator allowing to determine the acidity of a sample. If there is a neutral sample (pH=7), a litmus paper does not change colour. In an acidic sample (pH<7) it turns red, while in basic (pH>7) it becomes blue.

Among the 4 compounds provided, H₂O and BaCl₂ will not change the colour of the litmus paper, but HClO and NH₄OH will. Since HClO is a donor of protons H⁺ which are representing acidic media, by dissolving it in water the litmus paper will turn red, while NH₄OH will colour it blue since one of the products of its dissociation is basic OH^- group.