Question

1. drag and drop the equations with the descriptions.

$2\text{al}(s) + 3\text{cucl}_2(aq) \
ightarrow 2\text{alcl}_3(aq) + 3\text{cu}(g)$
$2\text{li}(s) + 2\text{h}_2\text{o}(l) \
ightarrow 2\text{lioh}(aq) + \text{h}_2(g)$
$\text{mg}(s) + \text{hcl}(aq) \
ightarrow \text{mgcl}_2(aq) + \text{h}_2(g)$
$2\text{nai}(aq) + \text{cl}_2(g) \
ightarrow 2\text{nacl}(aq) + \text{i}_2(g)$
choices
the replacement of a halogen by another halogen
the replacement of hydrogen in an acid by a metal
the replacement of hydrogen in water by a metal
the replacement of a metal cation by another metal

1. balance the single replacement reaction by typing the numbers in the blanks. type in 1 if the coefficient is 1.

$\underline{\quad} \text{mg} + \underline{\quad} \text{al(oh)}_3 \
ightarrow \underline{\quad} \text{mg(oh)}_2 + \underline{\quad} \text{al}$

1. balance the single replacement reaction by typing the numbers in the blanks. type in 1 if the coefficient is 1.

$\text{fe} + \text{nii}_2 \
ightarrow \text{fei}_2 + \text{ni}$

Explanation:

Question 4:

Step 1: Analyze \( 2\text{Al}(s) + 3\text{CuCl}_2(aq)

ightarrow 2\text{AlCl}_3(aq) + 3\text{Cu}(g) \)
In this reaction, aluminum (Al) replaces copper (Cu) in \( \text{CuCl}_2 \). So it's the replacement of a metal cation (Cu²⁺) by another metal (Al).

Step 2: Analyze \( 2\text{Li}(s) + 2\text{H}_2\text{O}(l)

ightarrow 2\text{LiOH}(aq) + \text{H}_2(g) \)
Lithium (Li) reacts with water, replacing hydrogen in water. So this is the replacement of hydrogen in water by a metal.

Step 3: Analyze \( \text{Mg}(s) + \text{HCl}(aq)

ightarrow \text{MgCl}_2(aq) + \text{H}_2(g) \)
Magnesium (Mg) reacts with hydrochloric acid (HCl), replacing hydrogen in the acid (HCl). So this is the replacement of hydrogen in an acid by a metal.

Step 4: Analyze \( 2\text{NaI}(aq) + \text{Cl}_2(g)

ightarrow 2\text{NaCl}(aq) + \text{I}_2(g) \)
Chlorine (Cl₂) replaces iodine (I⁻) in NaI. So it's the replacement of a halogen (I) by another halogen (Cl).

Step 1: Balance OH groups

On the left, \( \text{Al(OH)}_3 \) has 3 OH⁻. On the right, \( \text{Mg(OH)}_2 \) has 2 OH⁻. The least common multiple of 3 and 2 is 6. So we need 2 moles of \( \text{Al(OH)}_3 \) (giving 6 OH⁻) and 3 moles of \( \text{Mg(OH)}_2 \) (giving 6 OH⁻).
So now the equation is: \( \text{Mg} + 2\text{Al(OH)}_3
ightarrow 3\text{Mg(OH)}_2 + \text{Al} \)

Step 2: Balance Mg and Al

Now, for Mg: on the right we have 3 \( \text{Mg(OH)}_2 \), so we need 3 Mg on the left. For Al: on the left we have 2 \( \text{Al(OH)}_3 \), so we need 2 Al on the right.
So the balanced equation is: \( 3\text{Mg} + 2\text{Al(OH)}_3
ightarrow 3\text{Mg(OH)}_2 + 2\text{Al} \)

Step 1: Check atoms

• Fe: 1 on left, 1 on right (balanced initially).
• Ni: 1 on left (in \( \text{NiI}_2 \)), 1 on right (balanced initially).
• I: 2 on left (in \( \text{NiI}_2 \)), 2 on right (in \( \text{FeI}_2 \)) (balanced initially).

Wait, if the reaction is \( \text{Fe} + \text{NiI}_2
ightarrow \text{FeI}_2 + \text{Ni} \), it's already balanced? But maybe the original reaction was different. Wait, if it's \( \text{Fe} + \text{NiI}_3
ightarrow \text{FeI}_3 + \text{Ni} \), but the user wrote "FeI₂ + Ni" from "NiI₂". Wait, let's re - check.
For \( \text{Fe} + \text{NiI}_2
ightarrow \text{FeI}_2 + \text{Ni} \):

• Fe: 1 left, 1 right.
• Ni: 1 left, 1 right.
• I: 2 left, 2 right.

So coefficients are 1, 1, 1, 1. But maybe the user made a typo, but assuming the reaction is \( \text{Fe} + \text{NiI}_2
ightarrow \text{FeI}_2 + \text{Ni} \), balance:

Step 1: Balance Fe

1 Fe on left, 1 on right.

Step 2: Balance Ni

1 Ni on left, 1 on right.

Step 3: Balance I

2 I on left (NiI₂), 2 on right (FeI₂).
So balanced equation: \( 1\text{Fe} + 1\text{NiI}_2
ightarrow 1\text{FeI}_2 + 1\text{Ni} \)

Answer:

• \( 2\text{Al}(s) + 3\text{CuCl}_2(aq)

ightarrow 2\text{AlCl}_3(aq) + 3\text{Cu}(g) \): the replacement of a metal cation by another metal

• \( 2\text{Li}(s) + 2\text{H}_2\text{O}(l)

ightarrow 2\text{LiOH}(aq) + \text{H}_2(g) \): the replacement of hydrogen in water by a metal

• \( \text{Mg}(s) + \text{HCl}(aq)

ightarrow \text{MgCl}_2(aq) + \text{H}_2(g) \): the replacement of hydrogen in an acid by a metal

• \( 2\text{NaI}(aq) + \text{Cl}_2(g)

ightarrow 2\text{NaCl}(aq) + \text{I}_2(g) \): the replacement of a halogen by another halogen

Question 5: