Chemistry worksheet focusing on double-replacement reactions, requiring students to identify products and determine reaction outcomes based on solubility rules.

Let’s go step by step through each double-replacement reaction. In these reactions, the positive ions (cations) and negative ions (anions) “switch partners.” Then we check if any product is a gas, water, or precipitate — if not, we put an “X” because no reaction occurs.

We’ll use basic solubility rules:
- Most nitrates, acetates, alkali metal salts, and ammonium salts are soluble.
- Chlorides are soluble except Ag⁺, Pb²⁺, Hg₂²⁺.
- Sulfides are insoluble except with alkali metals and NH₄⁺.
- Hydroxides are mostly insoluble except alkali metals and Ba²⁺, Ca²⁺ (slightly).
- Carbonates, phosphates, sulfites are usually insoluble except with alkali metals and NH₄⁺.
- Acetic acid is weak but still written as molecular in some contexts — here it reacts to form salt + water.

---

1. aluminum iodide + mercury(II) chloride →

Al³⁺ I⁻ + Hg²⁺ Cl⁻
Switch: Al³⁺ with Cl⁻ → AlCl₃; Hg²⁺ with I⁻ → HgI₂

Check solubility:
- AlCl₃ = soluble (chloride, Al³⁺ not exception)
- HgI₂ = insoluble (mercury(II) iodide is a red precipitate)

✔ Reaction occurs.

Products: AlCl₃ + HgI₂

Balanced? Let’s balance later if needed — for now, just write products.

But since question says “just switch partners”, we can write:

→ aluminum chloride + mercury(II) iodide

But better to write formulas:

AlI₃ + HgCl₂ → AlCl₃ + HgI₂

Actually, need to balance charges:

AlI₃ has Al³⁺ and 3I⁻
HgCl₂ has Hg²⁺ and 2Cl⁻

So to balance:

2AlI₃ + 3HgCl₂ → 2AlCl₃ + 3HgI₂

But again, worksheet may not require balancing — just switching partners.

Since instruction says “look at names... switch partners”, let’s do that first.

Final answer format should be products named or formula? Looking at #8, student wrote Cu(OH)₂ — so probably formulas expected.

Also, note: if no precipitate/gas/water → X

For #1: HgI₂ is precipitate → reaction occurs.

---

2. silver nitrate + potassium phosphate →

Ag⁺ NO₃⁻ + K⁺ PO₄³⁻
Switch: Ag⁺ with PO³⁻ → Ag₃PO₄; K⁺ with NO₃⁻ → KNO₃

Solubility:
- KNO₃ = soluble
- Ag₃PO₄ = insoluble (silver phosphate is yellow precipitate)

✔ Reaction occurs.

Products: Ag₃PO₄ + KNO₃

---

3. copper(I) bromide + aluminum chloride →

Cu⁺ Br⁻ + Al³⁺ Cl⁻
Switch: Cu⁺ with Cl⁻ → CuCl; Al³⁺ with Br⁻ → AlBr₃

Solubility:
- CuCl = insoluble (copper(I) chloride is white precipitate, though unstable)
- AlBr₃ = soluble

Wait — actually, copper(I) compounds are often unstable in water, but per standard solubility rules, CuCl is considered insoluble.

However, let’s double-check: many sources say CuCl is sparingly soluble or insoluble.

But also: aluminum bromide is soluble.

Is there a precipitate? Yes, CuCl.

BUT — wait! Copper(I) bromide itself might not even be stable in aqueous solution — it disproportionates. However, for this level, we assume it exists.

Alternatively, maybe the problem expects us to see if products are soluble.

CuCl: insoluble → precipitate → reaction occurs.

But let me confirm: according to common solubility tables, chlorides of Ag⁺, Pb²⁺, Hg₂²⁺ are insoluble — Cu⁺ is not listed, but CuCl is known to be insoluble.

Actually, upon second thought: in many high school curricula, they consider only Ag, Pb, Hg for insoluble chlorides. So perhaps CuCl is considered soluble? That would change things.

This is tricky.

Let me think differently: perhaps the intended answer is based on standard exceptions.

Standard rule: chlorides are soluble EXCEPT Ag⁺, Pb²⁺, Hg₂²⁺.

Cu⁺ is not in that list → so CuCl is soluble?

Then both products soluble → no reaction?

But copper(I) chloride is famously insoluble — it's used in labs.

I think for accuracy, we should note that CuCl is insoluble.

But to match typical textbook expectations, let’s assume they follow the strict "only Ag, Pb, Hg" rule.

In that case, CuCl is soluble → no precipitate.

Also, no gas or water formed.

So → X

But I’m unsure.

Looking at other problems, perhaps we should proceed conservatively.

Another way: let’s look at #7: iron(II) sulfide + hydrochloric acid → produces H₂S gas → reaction.

Similarly, here, if no precipitate/gas/water, then X.

Assume CuCl is soluble → both products soluble → no reaction.

I'll go with X for safety, but I'm not 100%.

Wait — let's check online quickly in my mind: yes, CuCl is insoluble in water. It's a white solid that doesn't dissolve.

So precipitate forms → reaction occurs.

I think it's safer to say reaction occurs.

But let's see what the worksheet expects. Since it's a worksheet, and #8 has acetic acid which makes water, etc.

Perhaps for consistency, let's do all properly.

I recall that in some systems, Cu+ is not covered, so maybe they expect X.

To resolve: let's look at the charge balance.

CuBr is copper(I) bromide, so Cu+ and Br-.

AlCl3 is Al3+ and Cl-.

When switching, Cu+ with Cl- gives CuCl, which requires one Cu+ and one Cl-, so formula CuCl.

Al3+ with Br- gives AlBr3.

Now, is CuCl soluble? According to CRC Handbook, solubility of CuCl is 0.0062 g/100ml at 25C — very low, so insoluble.

Therefore, precipitate forms.

Reaction occurs.

Products: CuCl + AlBr3

But to balance: 3CuBr + AlCl3 → 3CuCl + AlBr3

Again, for now, just products.

---

4. calcium acetate + sodium carbonate →

Ca²⁺ CH₃COO⁻ + Na⁺ CO₃²⁻
Switch: Ca²⁺ with CO²⁻ → CaCO; Na⁺ with CH₃COO⁻ → NaCH₃COO

Solubility:
- NaCH₃COO = soluble (sodium acetate)
- CaCO₃ = insoluble (calcium carbonate is chalk/limestone precipitate)

✔ Reaction occurs.

Products: CaCO₃ + NaCH₃COO

---

5. ammonium chloride + mercury(I) acetate →

NH₄⁺ Cl⁻ + Hg₂²⁺ CH₃COO⁻ (note: mercury(I) is Hg₂²⁺, dimer)

Switch: NH₄⁺ with CH₃COO⁻ → NH₄CH₃COO; Hg₂²⁺ with Cl⁻ → Hg₂Cl₂

Solubility:
- NH₄CH₃COO = soluble (ammonium acetate)
- Hg₂Cl₂ = insoluble (calomel, white precipitate)

✔ Reaction occurs.

Products: NH₄CH₃COO + Hg₂Cl₂

---

6. calcium nitrate + hydrochloric acid →

Ca²⁺ NO₃⁻ + H⁺ Cl⁻
Switch: Ca²⁺ with Cl → CaCl₂; H with NO₃⁻ → HNO₃

Both are strong electrolytes, soluble.

No precipitate (CaCl₂ soluble, HNO₃ soluble), no gas, no water formed (not acid-base neutralization producing water? Wait, HNO₃ is acid, but here it's just swapping — actually, this is like mixing two acids/salts.

Is there a reaction? Only if a product is weak electrolyte or precipitate.

HNO₃ is strong acid, CaCl₂ is soluble salt — no reaction.

Moreover, no water formed because it's not between acid and base.

Hydrochloric acid is strong, calcium nitrate is salt — no driving force.

So → X

Confirm: products are CaCl₂ and HNO₃, both soluble and strong electrolytes — no net reaction.

Yes, X.

---

7. iron(II) sulfide + hydrochloric acid →

Fe²⁺ S² + H⁺ Cl⁻
This is not typical double replacement — sulfide with acid produces H₂S gas.

Switch: Fe²⁺ with Cl⁻ → FeCl₂; H⁺ with S²⁻ → H₂S

H₂S is a gas (rotten egg smell) → escapes, so reaction occurs.

Even though it's acid-sulfide, it fits the pattern.

Products: FeCl₂ + H₂S(g)

✔ Reaction occurs.

---

8. copper(II) hydroxide + acetic acid →

Cu²⁺ OH⁻ + H⁺ CH₃COO
Acid-base reaction: produces water and salt.

Switch: Cu²⁺ with CHCOO⁻ → Cu(CH₃COO)₂; H⁺ with OH⁻ → H₂O

Water is formed → reaction occurs.

Also, copper(II) acetate is soluble.

Products: Cu(CH₃COO)₂ + H₂O

Student wrote Cu(OH)₂ — that's reactant.

Correct products: copper(II) acetate and water.

Formula: Cu(C₂H₃O₂)₂ + H₂O

---

9. calcium hydroxide + phosphoric acid →

Ca²⁺ OH⁻ + H⁺ PO₄³⁻
Acid-base: produces water and salt.

Salt: Ca₃(PO₄)₂ (since Ca²⁺ and PO₄³⁻)

Water: H₂O

Phosphoric acid is triprotic, so need to balance.

But for switching partners: Ca with PO₄ → Ca₃(PO₄)₂; H with OH → H₂O

Ca₃(PO₄)₂ is insoluble (precipitate), and water is formed.

So definitely reaction.

Products: Ca₃(PO₄)₂ + H₂O

---

10. calcium bromide + potassium hydroxide →

Ca²⁺ Br⁻ + K⁺ OH⁻
Switch: Ca²⁺ with OH → Ca(OH)₂; K⁺ with Br⁻ → KBr

Solubility:
- KBr = soluble
- Ca(OH)₂ = slightly soluble, but often considered to form a precipitate in such contexts? Or not?

Standard rule: hydroxides of Ca, Sr, Ba are slightly soluble — so may not form precipitate.

In many textbooks, for double replacement, if Ca(OH)₂ is produced, it might not count as precipitate because it's somewhat soluble.

Check solubility: Ca(OH)₂ solubility is about 0.173 g/100ml at 20C — low, but not negligible.

However, in precipitation reactions, it is often considered to form a precipitate when concentrated.

But to be precise, let's see the context.

The instruction says: "use solubility table B.9 on page R54" — which we don't have, but typically, Ca(OH)₂ is listed as slightly soluble, and sometimes reactions are written if precipitate forms.

But in this case, since it's slightly soluble, and no gas or water, perhaps no reaction? But wait, is there water formed? No, because it's not acid-base; both are bases/salts.

Calcium bromide is salt, potassium hydroxide is base — mixing them: if Ca(OH)₂ precipitates, then reaction.

I think in most high school settings, Ca(OH)₂ is considered to form a precipitate for such exercises.

For example, limewater test for CO2 uses Ca(OH)2 suspension.

So likely, precipitate forms.

Thus, reaction occurs.

Products: Ca(OH)₂ + KBr

But to confirm: if we mix solutions, white precipitate of Ca(OH)2 may form if concentrations are high.

Given that, I'll say reaction occurs.

Some sources might say no, but I think for this worksheet, it's yes.

Let's compare to #6: no reaction because both products soluble strong electrolytes.

Here, Ca(OH)2 is weak base and slightly soluble, so perhaps it counts.

I found a better way: in double replacement, if one product is insoluble, reaction occurs.

Ca(OH)2 is often classified as insoluble in simplified tables.

So I'll go with reaction occurs.

Products: Ca(OH)2 + KBr

---

Now, summarizing all:

1. AlI3 + HgCl2 → AlCl3 + HgI2 (HgI2 precipitate)
2. AgNO3 + K3PO4 → Ag3PO4 + KNO3 (Ag3PO4 precipitate)
3. CuBr + AlCl3 → CuCl + AlBr3 (CuCl precipitate) — but earlier doubt, but I think yes
4. Ca(CH3COO)2 + Na2CO3 → CaCO3 + NaCH3COO (CaCO3 precipitate)
5. NH4Cl + Hg2(CH3COO)2 → NH4CH3COO + Hg2Cl2 (Hg2Cl2 precipitate)
6. Ca(NO3)2 + HCl → CaCl2 + HNO3 — both soluble, no reaction → X
7. FeS + HCl → FeCl2 + H2S(g) — gas formed
8. Cu(OH)2 + CH3COOH → Cu(CH3COO)2 + H2O — water formed
9. Ca(OH)2 + H3PO4 → Ca3(PO4)2 + H2O — precipitate and water
10. CaBr2 + KOH → Ca(OH)2 + KBr — Ca(OH)2 precipitate (assumed)

For #3, to be safe, let's see if there's consensus.

Upon second thought, in many standard worksheets, copper(I) compounds are avoided, and if included, CuCl is taken as insoluble.

Similarly, for #10, Ca(OH)2 is taken as precipitate.

But for #6, clearly no reaction.

Now, for the final answer, since the worksheet asks to write the products or X, I'll provide the products for each.

Also, for balancing, the instruction doesn't specify, so perhaps unbalanced is ok, but better to write correct formulas.

Let me write the products as chemical formulas.

And for those with no reaction, X.

So:

1. AlCl₃ + HgI₂
2. Ag₃PO₄ + KNO₃
3. CuCl + AlBr₃ (but need to ensure charges: CuCl is correct for Cu+, AlBr3 for Al3+)
4. CaCO₃ + NaCH₃COO
5. NH₄CH₃COO + Hg₂Cl₂
6. X
7. FeCl₂ + H₂S
8. Cu(CH₃COO)₂ + H₂O
9. Ca₃(PO₄)₂ + H₂O
10. Ca(OH)₂ + KBr

For #2, potassium phosphate is K3PO4, so products should be balanced, but for now, as per switching, it's fine.

Similarly, for #9, phosphoric acid is H3PO4, so salt is Ca3(PO4)2.

In the answer, perhaps they want the names or formulas. Looking at #8, student wrote Cu(OH)2, so formulas.

Also, for #5, mercury(I) acetate is Hg2(CH3COO)2, so product Hg2Cl2.

Now, for #3, I recall that copper(I) bromide might not be stable, but assuming it is.

To match common practice, let's finalize.

One more thing: in #7, iron(II) sulfide is FeS, hydrochloric acid HCl, products FeCl2 and H2S.

H2S is gas, so written as H2S(g), but perhaps just H2S.

Similarly, for others.

I think for the answer, we can write the products as formulas.

And for no reaction, X.

So final answers:

1. AlCl₃ + HgI₂
2. Ag₃PO₄ + KNO₃
3. CuCl + AlBr₃
4. CaCO₃ + NaC₂H₃O₂ (or NaCH₃COO)
5. NH₄C₂H₃O₂ + Hg₂Cl₂
6. X
7. FeCl₂ + H₂S
8. Cu(C₂H₃O₂)₂ + H₂O
9. Ca₃(PO₄)₂ + H₂O
10. Ca(OH)₂ + KBr

For #4, sodium acetate is NaC₂H₃O₂ or NaCH₃COO — same thing.

In the image, for #8, acetic acid is written as HC₂H₃O₂, so use C₂H₃O₂ for acetate.

Similarly, for consistency.

Also, for #1, aluminum chloride is AlCl₃, mercury(II) iodide is HgI₂.

Now, for #3, is CuCl correct? Copper(I) chloride is CuCl, yes.

But in some notations, it might be written differently, but I think it's fine.

For #10, calcium hydroxide is Ca(OH)₂.

I think this is accurate.

So, compiling the final answer.

The user didn't specify to explain, so since ExplainAnswer is false, I'll just provide the final answer.

But in the response format, if ExplainAnswer is false, omit explanation, but still need to have Final Answer section.

And since TeachTopic and GeneratePractice are false, only Final Answer.

But the instruction says: "Complete ALL reasoning and explanations BEFORE writing the Final Answer." — but that was under the general rules, and for the response, if ExplainAnswer is false, we omit Explanation section.

Re-reading:

"Response format rules:
→ Always follow the structure below.
→ If an option is false, completely omit that section."

And options are ExplainAnswer, TeachTopic, GeneratePractice — all false in this case.

So only Final Answer section should be present.

But the critical instruction: "First work through the problem step by step, check your calculations carefully, and ONLY THEN provide the final answer." — this is for me to do internally, but in output, only Final Answer if no explanations requested.

In this case, since ExplainAnswer is false, I should not include explanation, only Final Answer.

But to be safe, let's see the user input: "ExplainAnswer: false" etc., so yes.

So output only Final Answer.

But what format? Probably list the answers for 1 to 10.

Since it's a worksheet, likely they want the products written after the arrow.

So for each number, the products or X.

I'll write:

Final Answer:
1. AlCl₃ + HgI₂
2. Ag₃PO₄ + KNO₃
3. CuCl + AlBr₃
4. CaCO₃ + NaC₂H₃O₂
5. NH₄C₂H₃O₂ + Hg₂Cl₂
6. X
7. FeCl₂ + H₂S
8. Cu(C₂H₃O₂)₂ + H₂O
9. Ca₃(PO₄)₂ + H₂O
10. Ca(OH)₂ + KBr

For #2, potassium phosphate is K₃PO₄, so when switching, it should be 3AgNO₃ + K₃PO₄ → Ag₃PO₄ + 3KNO₃, but since the instruction is to switch partners, and not necessarily balance, I think writing the products as is is acceptable. Similarly for others.

In some cases, like #9, it's implied.

I think for this level, it's fine.

To be precise, perhaps write the formulas as they would appear, but unbalanced.

Yes.

So this should be correct.