Question

3. For the following chemical reactions in which a gas is involved, describe the expected change in the indicators that you would observe in the presence of this gas. Refer back to your report sheet results to determine what observations will be present for the gases below. It does not make a difference if the gas is a reactant or product. For each reaction, indicate what color each color indicator would turn in the presence of the stated gas as well as if we would see effervescence. Be detailed and explain what you would expect to see for all four indicator squares as well as presence/absence of gas bubbles.

Expected Indicator Observations (be specific)

Chemical Reactions
a. SO2(g)+ H₂O → H₂SO3

b. 2H₂O + SO₂(g) + I₂ → SO4^3-+2I^- + 4H^+

C. 2NO2(g) + H₂O → HNO₂ + HNO3

d. Cl₂ + 2I^- →l₂ + 2Cl^-

e. Cl₂(g) + H₂O → HCI + HCIO

f. NH3(g) + H₂O → NH4^+ + OH^-

Answer 1

Expected changes in color indicators for chemical reactions involving gases such as SO2(g) and NO2(g) will generally result in acid formation, turning litmus paper red. For reactions producing gases, effervescence is expected. NH3(g) in water results in a basic solution, turning litmus paper blue and phenolphthalein pink.

Step-by-step explanation:

Describing the expected changes in indicators for chemical reactions where a gas is involved requires considering what type of reaction is occurring and the properties of the gas involved. For example:

• SO2(g) is a non-metal oxide, which will typically result in an acidic solution when combined with water, forming H2SO3 (sulfurous acid). Indicators such as litmus paper will turn red in the presence of this acid.
• In the reaction involving NO2(g), which produces both nitrous acid (HNO2) and nitric acid (HNO3), we would again expect indicators like litmus to turn red due to the acidic nature of the products.
• The reaction of Cl2(g) with water to form HCl and HClO will also lead to an acidic solution, and litmus paper would turn red in the presence of these acids as well.
• For NH3(g), which forms a basic solution with water (NH4+ and OH-), litmus paper would turn blue, and phenolphthalein would turn pink due to the basicity of the solution.

For reactions resulting in gases, bubbles or effervescence would be observed. These observations could be made for each reaction if a gas is being produced or consumed.