Question

scoring: your score will be based on the number of correct matches minus the number of incorrect matches. there is no penalty for missing matches.
use the references to access important values if needed for this question.
indicate whether each of the following compounds will give an acidic, basic or neutral solution when dissolved in water.
ammonium
perchlorate
sodium nitrite
calcium iodide
ammonium iodide
the ph will be less than
7.
the ph will be
approximately equal to
7.
the ph will be greater
than 7.

Explanation:

Step1: Analyze ammonium perchlorate ($\ce{NH4ClO4}$)

Ammonium perchlorate is a salt of a weak base ($\ce{NH3\cdot H2O}$) and a strong acid ($\ce{HClO4}$). When it dissolves in water, the ammonium ion ($\ce{NH4+}$) hydrolyzes: $\ce{NH4+ + H2O
ightleftharpoons NH3\cdot H2O + H+}$. This produces $\ce{H+}$ ions, so the solution is acidic. The pH will be less than 7.

Step2: Analyze sodium nitrite ($\ce{NaNO2}$)

Sodium nitrite is a salt of a strong base ($\ce{NaOH}$) and a weak acid ($\ce{HNO2}$). The nitrite ion ($\ce{NO2-}$) hydrolyzes: $\ce{NO2- + H2O
ightleftharpoons HNO2 + OH-}$. This produces $\ce{OH-}$ ions, so the solution is basic. The pH will be greater than 7.

Step3: Analyze calcium iodide ($\ce{CaI2}$)

Calcium iodide is a salt of a strong base ($\ce{Ca(OH)2}$) and a strong acid ($\ce{HI}$). Neither the calcium ion ($\ce{Ca^{2+}}$) nor the iodide ion ($\ce{I-}$) hydrolyzes significantly. So the solution is neutral. The pH will be approximately equal to 7.

Step4: Analyze ammonium iodide ($\ce{NH4I}$)

Ammonium iodide is a salt of a weak base ($\ce{NH3\cdot H2O}$) and a strong acid ($\ce{HI}$). The ammonium ion ($\ce{NH4+}$) hydrolyzes: $\ce{NH4+ + H2O
ightleftharpoons NH3\cdot H2O + H+}$. This produces $\ce{H+}$ ions, so the solution is acidic. The pH will be less than 7.

Answer:

• ammonium perchlorate: The pH will be less than 7.
• sodium nitrite: The pH will be greater than 7.
• calcium iodide: The pH will be approximately equal to 7.
• ammonium iodide: The pH will be less than 7.