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In a reaction involving $Pb^{2+}$ and $I^{-}$ ions, a solid forms. How does this relate to the concept of solubility?
In a reaction involving $Pb^{2+}$ and $I^{-}$ ions, a solid forms. How does this relate to the concept of solubility?
- The presence of a solid has no correlation with the solubility of the involved ions.
- The solid indicates that the compound formed by $Pb^{2+}$ and $I^{-}$ is poorly soluble. (correct)
- The solid indicates that the compound formed by $Pb^{2+}$ and $I^{-}$ is highly soluble.
- More information about the temperature of the solution is needed to determine the relation.
When mixing two colorless salt solutions, a yellow precipitate forms. What does this observation imply about the reaction?
When mixing two colorless salt solutions, a yellow precipitate forms. What does this observation imply about the reaction?
- The reaction is an acid-base neutralization, producing a salt and water.
- The reaction is at equilibrium, with the rate of dissolution equaling the rate of precipitation.
- The reaction is a precipitation reaction, where a solid is formed from ions in solution. (correct)
- The reaction is a redox reaction, involving the transfer of electrons.
Consider the reaction: $Pb^{2+}(aq) + 2I^-(aq) \rightarrow PbI_2(s)$. Which statement accurately describes this reaction?
Consider the reaction: $Pb^{2+}(aq) + 2I^-(aq) \rightarrow PbI_2(s)$. Which statement accurately describes this reaction?
- The spectator ions, $K^+$ and $NO_3^-$, participate directly in forming the solid $PbI_2$.
- The reaction will not occur spontaneously; the $PbI_2$ product requires a catalyst.
- This reaction is a precipitation reaction, forming a solid $PbI_2$ from its constituent ions in solution. (correct)
- This reaction is a redox reaction, involving the transfer of electrons between lead and iodide ions.
In an experiment, solutions of $Mg^{2+}$ and $SO_4^{2-}$ are mixed with solutions of $Na^+$ and $NO_3^-$. According to the text, what likely outcome is observed?
In an experiment, solutions of $Mg^{2+}$ and $SO_4^{2-}$ are mixed with solutions of $Na^+$ and $NO_3^-$. According to the text, what likely outcome is observed?
In ensuring no unwanted precipitation occurs in an aquarium, which combination of ions should be avoided?
In ensuring no unwanted precipitation occurs in an aquarium, which combination of ions should be avoided?
In a scenario where iron(III) nitrate and sodium hydroxide solutions are mixed together, a brown solid forms. What is the chemical formula of this brown solid?
In a scenario where iron(III) nitrate and sodium hydroxide solutions are mixed together, a brown solid forms. What is the chemical formula of this brown solid?
What happens to the concentration of ions in a solution of a slightly soluble salt after it has reached a dynamic equilibrium?
What happens to the concentration of ions in a solution of a slightly soluble salt after it has reached a dynamic equilibrium?
What distinguishes a homogeneous equilibrium from a heterogeneous equilibrium?
What distinguishes a homogeneous equilibrium from a heterogeneous equilibrium?
Why is it important to remove phosphate ions from wastewater in sewage treatment?
Why is it important to remove phosphate ions from wastewater in sewage treatment?
In a chemical factory that uses mercury compounds, what method can be used to remove $Hg^{2+}$ ions from its wastewater?
In a chemical factory that uses mercury compounds, what method can be used to remove $Hg^{2+}$ ions from its wastewater?
Before discharging wastewater from a chemical factory, what factor is most crucial to consider in the precipitation of unwanted ions?
Before discharging wastewater from a chemical factory, what factor is most crucial to consider in the precipitation of unwanted ions?
To synthesize copper(II) phosphate ($Cu_3(PO_4)_2$), which combination of solutions would be most appropriate?
To synthesize copper(II) phosphate ($Cu_3(PO_4)_2$), which combination of solutions would be most appropriate?
When preparing a sparingly soluble salt, such as sodium nitrate, using precipitation, what step should be taken after filtering the precipitate to obtain the salt?
When preparing a sparingly soluble salt, such as sodium nitrate, using precipitation, what step should be taken after filtering the precipitate to obtain the salt?
In an experiment, you have a white solid that could be either sodium sulfite ($Na_2SO_3$) or sodium sulfate ($Na_2SO_4$). When testing this solid with zinc nitrate, a precipitate is formed. What was the original compound?
In an experiment, you have a white solid that could be either sodium sulfite ($Na_2SO_3$) or sodium sulfate ($Na_2SO_4$). When testing this solid with zinc nitrate, a precipitate is formed. What was the original compound?
When combining two solutions to form a sparingly soluble salt, what dictates the amount of precipitate formed?
When combining two solutions to form a sparingly soluble salt, what dictates the amount of precipitate formed?
Flashcards
Neerslag (Precipitate)
Neerslag (Precipitate)
A substance that doesn't dissolve in the reaction mix and settles out.
Neerslagreactie (Precipitation reaction)
Neerslagreactie (Precipitation reaction)
A reaction where a solid (precipitate) forms from mixing solutions.
Oplosbaarheidstabel (Solubility table)
Oplosbaarheidstabel (Solubility table)
A table (Binas tabel 45A) showing the solubility of different ionic compounds.
Spectator ions
Spectator ions
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Neerslagvergelijking (Net ionic equation)
Neerslagvergelijking (Net ionic equation)
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Dynamisch evenwicht (Dynamic equilibrium)
Dynamisch evenwicht (Dynamic equilibrium)
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Homogeen evenwicht (Homogeneous equilibrium)
Homogeen evenwicht (Homogeneous equilibrium)
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Ionsoorten verwijderen (Removing ion species)
Ionsoorten verwijderen (Removing ion species)
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Een zout maken (Making a salt)
Een zout maken (Making a salt)
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Ionsoorten aantonen (Identifying ion species)
Ionsoorten aantonen (Identifying ion species)
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Stoichiometrische verhouding (Stoichiometric ration)
Stoichiometrische verhouding (Stoichiometric ration)
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Overmaat (Excess)
Overmaat (Excess)
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Rekenschema (Calculation schema)
Rekenschema (Calculation schema)
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Massa omrekenen naar mol (mass --> mol)
Massa omrekenen naar mol (mass --> mol)
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Mol gas omrekenen naar volume (Mol gas --> Volume)
Mol gas omrekenen naar volume (Mol gas --> Volume)
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Study Notes
- Precipitation occurs when a substance is insoluble in the reaction mixture leading it to settle out.
- This is used in creating dyes like porphyrins from metal and non-metal ions.
- Porphyrins are naturally occurring dyes responsible for feather colors in birds like the Turaco from New Guinea.
Precipitation Reactions
- Use Binas table 45A to determine if a salt is soluble.
- The letter "s" indicates that a solid will form if those ions come together in a solution.
- Precipitation happens when combined ion types form a poorly soluble salt.
Experiment 5.1
- Experiment involves mixing two salt solutions containing:
- Pb2+
- NO3
- K+
- I
- Both solutions are colorless.
- When combined a yellow solid, a precipitate, forms.
- This kind of reaction is called a precipitation reaction.
- To know the reaction, create a solubility table of the ions using Binas table 45A.
| NO3 | I | |
|---|---|---|
| Pb2+ | g | s |
| K+ | g | g |
- Letter "s" appears with Pb2+ and I-, this means those ions cannot exist together in a solution and react.
- The equation for this precipitation reaction is:
- Pb2+(aq) + 2I-(aq) → PbI2(s)
- K+ and NO3- ions remain in the solution.
- They do not appear in the reaction equation.
Experiment 5.2
- Magnesium sulfate and sodium nitrate solutions are combined, no change is visible.
- All combinations of ions are soluble, indicated by "g" in the solubility table.
- No precipitation reaction occurs.
| SO42- | NO3 | |
|---|---|---|
| Mg2+ | g | g |
| Na+ | g | g |
Experiment 5.3
- Aquariums contain dissolved salts.
- Undesirable precipitation reactions can occur.
- Avoid iron(III) and hydroxide ions to prevent iron(III) hydroxide from forming.
Example 1
- Add iron(III) nitrate to sodium hydroxide, a brown precipitate forms.
- Reaction: Fe3+(aq) + 3OH-(aq) → Fe(OH)3(s)
Dynamic Equilibrium
- Precipitation reactions remove ions from the solution.
- Not all ions of the precipitated salt disappear which begs the question: are still ions in the solution even after precipitation?
- Calcium nitrate and sodium sulfate solutions combine, a precipitate forms: calcium sulfate.
- Filtering the suspension reveals calcium and sulfate ions in the solution, confirming:
- Only some ions react to form calcium sulfate precipitate.
- Poorly soluble salts always have ions remaining in solution.
- After settling, the rate of ions entering the solution equals the rate of ions precipitating out, keeping the concentration constant.
Analogy with Iodine
- Dynamic equilibrium occurs with iodine distributing between water and petroleum ether.
- Poorly soluble salts: a dynamic equilibrium exists.
- It's a chemical equilibrium because two reversible reactions happen. It's a heterogeneous equilibrium because not all participating substances are in the same state.
- Chemical equilibrium is a form of dynamic equilibrium.
- General equation:
- CaSO4(s) ⇌ Ca2+(aq) + SO42-(aq)
- Double arrows indicate reaction occurs in both directions at the same time.
- Equilibrium is not considered in precipitation reactions except when explicitly stated.
Removal of Ions
- Precipitation reactions remove phosphate ions from solutions for reuse.
- Essential applications:
- Removing a kind of ion from a solution
- Producing a salt
- Identifying one type of ion in a solution
Chemical Factories
- Chemical factories use mercury compounds.
- Wastewater contains significant mercury(II) salts.
- Mercury is harmful and must be dealt with before wastewater can be released, must first remove Hg2+ ions via precipitation using carbonate ions (see table 5.12).
- Adding sodium carbonate solution to the waste water results in:
- Hg2+(aq) + CO32-(aq) → HgCO3(s)
- The precipitate is filtered, and the filtrate is released, but each removed Hg2+ ion is replaced by two Na+ ions, which are less harmful.
- Regular governmental checks are conducted on factory waste water to follow procedure.
- To remove one type of ion, combine it with an oppositely charged ion to form a poorly soluble salt.
Salt Creation
- To make copper phosphate, combine copper ions with phosphate ions.
- Use copper nitrate and sodium phosphate solutions to ensure copper phosphate precipitates exclusively because sodium and nitrate salts are highly soluble (see table 5.13b).
- Reaction: 3Cu2+(aq) + 2PO43-(aq) → Cu3(PO4)2(s)
- The solid precipitate is filtered, washed with water, and then dried.
- For soluble salts like sodium nitrate, evaporate the filtrate from the same process: Na+(aq) + NO3-(aq) → NaNO3(s).
- Avoid excess copper or phosphate ions in this case.
Identifying Ions
- To identify if a white powdered substance is sodium sulfite or sodium sulfate:
- Dissolve a small amount in water, creating a solution of Na+ and either SO32- or SO42-.
- Add a salt solution with a positive ion that will only react with one of the negative ions, for instance, zinc nitrate. If a precipitate forms, it confirms that the original substance was sodium sulfite because zinc sulfite is insoluble.
- If the precipitate forms with zinc then sulfUTE, otherwise, sulfATE .
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