Questions: A solution contains one or more of the following ions: Ag+, Ca2+, and Co2+. Lithium bromide is added to the solution and no precipitate forms. An excess of lithium sulfate is then added to the solution and a precipitate forms. The precipitate is filtered off and lithium phosphate is added to the remaining solution, producing a precipitate. Which ions are present in the original solution? Co2+ Ag+ Ca2+. Write a net ionic equation for the formation of the precipitate observed after the addition of lithium sulfate. Include physical states. net ionic equation: Write a net ionic equation for the formation of the precipitate observed after the addition of lithium phosphate. Include physical states.

A solution contains one or more of the following ions: Ag+, Ca2+, and Co2+. Lithium bromide is added to the solution and no precipitate forms. An excess of lithium sulfate is then added to the solution and a precipitate forms. The precipitate is filtered off and lithium phosphate is added to the remaining solution, producing a precipitate.

Which ions are present in the original solution?
Co2+
Ag+
Ca2+.

Write a net ionic equation for the formation of the precipitate observed after the addition of lithium sulfate. Include physical states.
net ionic equation: 

Write a net ionic equation for the formation of the precipitate observed after the addition of lithium phosphate. Include physical states.
Transcript text: A solution contains one or more of the following ions: $\mathrm{Ag}^{+}, \mathrm{Ca}^{2+}$, and $\mathrm{Co}^{2+}$. Lithium bromide is added to the solution and no precipitate forms. An excess of lithium sulfate is then added to the solution and a precipitate forms. The precipitate is filtered off and lithium phosphate is added to the remaining solution, producing a precipitate. Which ions are present in the original solution? $\mathrm{Co}^{2+}$ $\mathrm{Ag}^{+}$ $\mathrm{Ca}^{2+}$. Write a net ionic equation for the formation of the precipitate observed after the addition of lithium sulfate. Include physical states. net ionic equation: $\square$ Write a net ionic equation for the formation of the precipitate observed after the addition of lithium phosphate. Include physical states.
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Solution

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Solution Steps

Step 1: Identify the ions that do not form a precipitate with lithium bromide

Lithium bromide (LiBr) is added to the solution, and no precipitate forms. This indicates that none of the ions present in the solution form an insoluble bromide. The solubility rules tell us that:

  • $\mathrm{AgBr}$ is insoluble.
  • $\mathrm{CaBr_2}$ is soluble.
  • $\mathrm{CoBr_2}$ is soluble.

Since no precipitate forms, $\mathrm{Ag}^{+}$ is not present in the solution.

Step 2: Identify the ions that form a precipitate with lithium sulfate

An excess of lithium sulfate (Li_2SO_4) is added, and a precipitate forms. This indicates that at least one of the ions forms an insoluble sulfate. The solubility rules tell us that:

  • $\mathrm{CaSO_4}$ is slightly soluble (forms a precipitate in excess sulfate).
  • $\mathrm{CoSO_4}$ is soluble.

Since a precipitate forms, $\mathrm{Ca}^{2+}$ must be present in the solution.

Step 3: Identify the ions that form a precipitate with lithium phosphate

After filtering off the precipitate, lithium phosphate (Li_3PO_4) is added, and a precipitate forms. This indicates that at least one of the remaining ions forms an insoluble phosphate. The solubility rules tell us that:

  • $\mathrm{Ca_3(PO_4)_2}$ is insoluble.
  • $\mathrm{Co_3(PO_4)_2}$ is insoluble.

Since a precipitate forms, $\mathrm{Co}^{2+}$ must be present in the solution.

Step 4: Write the net ionic equation for the formation of the precipitate with lithium sulfate

The precipitate formed with lithium sulfate is $\mathrm{CaSO_4}$. The net ionic equation is: \[ \mathrm{Ca^{2+}(aq) + SO_4^{2-}(aq) \rightarrow CaSO_4(s)} \]

Step 5: Write the net ionic equation for the formation of the precipitate with lithium phosphate

The precipitate formed with lithium phosphate is $\mathrm{Co_3(PO_4)_2}$. The net ionic equation is: \[ 3\mathrm{Co^{2+}(aq) + 2PO_4^{3-}(aq) \rightarrow Co_3(PO_4)_2(s)} \]

Final Answer

The ions present in the original solution are: \[ \boxed{\mathrm{Ca^{2+}} \text{ and } \mathrm{Co^{2+}}} \]

Net ionic equation for the formation of the precipitate with lithium sulfate: \[ \boxed{\mathrm{Ca^{2+}(aq) + SO_4^{2-}(aq) \rightarrow CaSO_4(s)}} \]

Net ionic equation for the formation of the precipitate with lithium phosphate: \[ \boxed{3\mathrm{Co^{2+}(aq) + 2PO_4^{3-}(aq) \rightarrow Co_3(PO_4)_2(s)}} \]

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