Solubility Rules and Ionic Equations

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Explain why $K_3N$ is soluble while $Cu(OH)_2$ is not, referring to general solubility rules.

$K_3N$ is soluble because all compounds containing Group 1 cations such as potassium ($K^+$) are soluble. $Cu(OH)_2$ is insoluble because most hydroxide ($OH^−$) compounds are insoluble, except those of Group 1 elements and some Group 2 elements.

If a solution containing lead (II) ions is mixed with a solution containing iodide ions, a precipitate forms. Write the net ionic equation for this precipitation reaction, including state symbols.

$Pb^{2+}(aq) + 2I^-(aq) \rightarrow PbI_2(s)$

In the reaction of aqueous lithium chloride with aqueous lead(II) nitrate, identify the spectator ions. Briefly explain why they are considered spectator ions.

The spectator ions are lithium ($Li^+$) and nitrate ($NO_3^−$). They are considered spectator ions because they remain aqueous throughout the reaction and do not participate in the formation of the precipitate, lead(II) chloride.

A student attempts to conduct electricity using solid sodium chloride (NaCl), but it fails to conduct. Explain why, and then describe a method to make it conductive.

Solid NaCl does not conduct electricity because the ions are fixed in a lattice structure and cannot move freely. To make it conductive, you can either dissolve it in water to create aqueous ions or melt it into a molten state, allowing the ions to move freely and carry a charge. Signup and view all the answers

Based on the case study information, explain how the presence of blue-grey skin on the victim could assist forensic investigators and the chemical process behind the colour change.

The blue-grey skin suggests argyria, indicating silver ion ($Ag^+$) overaccumulation. This finding directs investigators to focus on sources of silver compounds at the scene. Argyria occurs when silver ions interact with proteins in the skin and are then changed by light exposure to silver sulfide or silver selenide, which present with a blue/grey colour. Signup and view all the answers

Write the chemical formulas for calcium sulfide and lead (II) iodide. Explain why the Roman numeral is necessary for lead but not for calcium.

Calcium sulfide: CaS; Lead (II) iodide: $PbI_2$. The Roman numeral is needed for lead because it's a transition metal and can have multiple oxidation states, whereas calcium is an alkaline earth metal with only one common oxidation state (+2). Signup and view all the answers

Write a balanced chemical equation and the corresponding ionic equation for the reaction between aqueous lithium chloride and aqueous lead(II) nitrate. What type of reaction is this?

Balanced chemical equation: $2LiCl(aq) + Pb(NO_3)_2(aq) \rightarrow 2LiNO_3(aq) + PbCl_2(s)$. Ionic equation: $2Cl^-(aq) + Pb^{2+}(aq) \rightarrow PbCl_2(s)$. This is a precipitation reaction. Signup and view all the answers

A solution of sodium sulfate ($Na_2SO_4$) is mixed with potassium hydroxide ($KOH$). Write a balanced chemical equation for the reaction. Will there be a precipitate?

Balanced chemical equation: $Na_2SO_4(aq) + 2KOH(aq) \rightarrow K_2SO_4(aq) + 2NaOH(aq)$. No precipitate will form because all products are soluble. Signup and view all the answers

Explain why ionic compounds conduct electricity in the molten or aqueous state but not in the solid state. Use a diagram to support your answer.

In the solid state, ions in ionic compounds are held in a fixed lattice structure and cannot move freely. When molten or dissolved in water, the ions are free to move and carry charge, allowing electrical conductivity. [Accompanying diagram should show a fixed lattice structure in solid state and freely moving ions in molten/aqueous state]. Signup and view all the answers

Based on the case study, the victim's blue-grey skin suggests argyria due to silver ion accumulation. If silver was ingested as silver nitrate ($AgNO_3$), what other chemicals introduced would cause a reaction with silver in the body?

A chloride source could react with the silver. For example, the silver could react with chloride ions to form insoluble silver chloride (AgCl) which would deposit in the skin. Signup and view all the answers

Write the chemical formulas for Calcium sulfide and Chromium (III) oxide.

Calcium sulfide: $CaS$; Chromium (III) oxide: $Cr_2O_3$ Signup and view all the answers

Write the balanced chemical equation for the reaction between aqueous lithium chloride and aqueous lead(II) nitrate.

$2LiCl(aq) + Pb(NO_3)_2(aq) \rightarrow 2LiNO_3(aq) + PbCl_2(s)$ Signup and view all the answers

Based on the case study, what evidence suggests the victim suffered from argyria, and how is this condition related to a specific ion?

The victim had blue-grey skin which is a characteristic of argyria. Argyria is caused by overaccumulation of silver ions in the body. Signup and view all the answers

Explain why ionic compounds can conduct electricity in molten or aqueous state but not in solid state.

In solid state, ions in ionic compounds are held in fixed positions in the crystal lattice and cannot move freely to carry a charge. However, when molten or dissolved in water, the ions are free to move and can conduct electricity. Signup and view all the answers

A solution of sodium sulfate ($Na_2SO_4$) is mixed with potassium hydroxide ($KOH$). Write a balanced equation for this reaction, and state whether a precipitate will form.

$Na_2SO_4(aq) + 2KOH(aq) \rightarrow K_2SO_4(aq) + 2NaOH(aq)$. No precipitate forms. Signup and view all the answers

Ionic Compound

A compound formed by the electrostatic attraction between ions.

Soluble Ionic Compound

Dissolves in water. Check solubility rules.