Single Replacement Reactions Worksheet with chemical equations to predict and balance.

To solve this worksheet, we need to use the Activity Series of Metals. This is a list that ranks metals from most reactive to least reactive.

The Rule: A more reactive metal can replace (kick out) a less reactive metal from a compound.
* If the single metal on the left is higher on the activity series than the metal in the compound, the reaction happens.
* If the single metal is lower, no reaction occurs (write N.R.).

Here are the approximate rankings for the metals involved in your problems (from most reactive to least):
1. Potassium (K) - Very Reactive
2. Barium (Ba)
3. Calcium (Ca)
4. Lithium (Li)
5. Iron (Fe)
6. Lead (Pb)
7. Copper (Cu)
8. Mercury (Hg)
9. Silver (Ag)
10. Gold (Au) - Least Reactive

*Note: Tin (Sn) and Nickel (Ni) fall somewhere between Iron and Lead.*

Let's go through each problem step-by-step:

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Step-by-Step Solutions

1) Fe + CuCl₂ →
* Check Activity: Is Iron (Fe) more active than Copper (Cu)? Yes. Iron is higher up.
* Reaction: Iron replaces Copper.
* Products: Iron becomes Iron(II) because Chlorine has a -1 charge ($Cl^-$), so $FeCl_2$. Copper is just solid $Cu$.
* Balance: We have 2 Cl on the right, so we need 2 Cl on the left. But wait, $CuCl_2$ already has 2 Cl. So it balances as is.
* Equation: $Fe + CuCl_2 \rightarrow FeCl_2 + Cu$

2) Hg + Sn(SO₄)₂ →
* Check Activity: Is Mercury (Hg) more active than Tin (Sn)? No. Mercury is very low on the list (noble metal-ish). Tin is much higher.
* Result: No Reaction.
* Answer: N.R.

3) Ba + Ni₃(PO₄)₂ →
* Check Activity: Is Barium (Ba) more active than Nickel (Ni)? Yes, Barium is an alkaline earth metal and very reactive.
* Reaction: Barium replaces Nickel.
* Products: Barium forms $Ba^{2+}$ and Phosphate is $PO_4^{3-}$. To balance charges (+2 and -3), we swap them to get subscripts: $Ba_3(PO_4)_2$. Nickel is just solid $Ni$.
* Balance:
* Left: 1 Ba, 3 Ni
* Right: 3 Ba, 1 Ni
* Add coefficient 3 to Ba on left. Add coefficient 3 to Ni on right.
* Equation: $3Ba + Ni_3(PO_4)_2 \rightarrow Ba_3(PO_4)_2 + 3Ni$

4) Pb + Au(NO₃)₃ →
* Check Activity: Is Lead (Pb) more active than Gold (Au)? Yes, Lead is much higher. Gold is at the very bottom.
* Reaction: Lead replaces Gold.
* Products: Lead is specified as $Pb^{4+}$ in the instructions. Nitrate is $NO_3^-$. So Lead Nitrate is $Pb(NO_3)_4$. Gold is solid $Au$.
* Balance:
* Left: 3 N (in nitrate)
* Right: 4 N (in nitrate)
* Find common multiple of 3 and 4, which is 12.
* Put 4 in front of $Au(NO_3)_3$ (to get 12 nitrates).
* Put 3 in front of $Pb(NO_3)_4$ (to get 12 nitrates).
* Now balance the metals: 4 Au on left $\rightarrow$ 4 Au on right. 3 Pb on right $\rightarrow$ 3 Pb on left.
* Equation: $3Pb + 4Au(NO_3)_3 \rightarrow 3Pb(NO_3)_4 + 4Au$

5) Li + HOH →
* Note: HOH is water ($H_2O$).
* Check Activity: Is Lithium (Li) more active than Hydrogen (H)? Yes, Lithium is extremely reactive with water.
* Reaction: Lithium replaces Hydrogen.
* Products: Lithium hydroxide ($LiOH$) and Hydrogen gas ($H_2$). Note: Hydrogen is diatomic.
* Balance:
* Left: 1 H (in water), Right: 3 H total (1 in LiOH, 2 in H2).
* Let's try balancing Oxygen first. 1 O on left, 1 O on right.
* Try putting a 2 in front of LiOH to handle the H2 gas?
* Let's restart balancing: $2Li + 2HOH \rightarrow 2LiOH + H_2$.
* Check: 2 Li, 2 O, 4 H on both sides.
* Equation: $2Li + 2HOH \rightarrow 2LiOH + H_2$

6) K + AgCl →
* Check Activity: Is Potassium (K) more active than Silver (Ag)? Yes, Potassium is at the top!
* Reaction: Potassium replaces Silver.
* Products: Potassium Chloride ($KCl$) and Silver ($Ag$).
* Balance: Already balanced. 1 of each atom.
* Equation: $K + AgCl \rightarrow KCl + Ag$

7) Ca + NaOH →
* Check Activity: Is Calcium (Ca) more active than Sodium (Na)? This is tricky. In the standard activity series, Sodium (Group 1) is actually slightly *more* active than Calcium (Group 2). However, in many high school contexts involving single replacement with bases, Calcium is often considered reactive enough to displace sodium or react vigorously with the water in the solution.
* *Correction/Refinement:* Strictly speaking, Sodium is higher than Calcium on the activity series. Therefore, Calcium cannot displace Sodium.
* Result: No Reaction.
* Answer: N.R.

8) Cu + Fe(OH)₃ →
* Check Activity: Is Copper (Cu) more active than Iron (Fe)? No. Iron rusts easily; copper does not. Iron is higher.
* Result: No Reaction.
* Answer: N.R.

9) Fe + Cu(OH)₂ →
* Check Activity: Is Iron (Fe) more active than Copper (Cu)? Yes.
* Reaction: Iron replaces Copper.
* Products: Iron(II) Hydroxide ($Fe(OH)_2$) and Copper ($Cu$).
* Balance: Already balanced.
* Equation: $Fe + Cu(OH)_2 \rightarrow Fe(OH)_2 + Cu$

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Final Answer:
1) $Fe + CuCl_2 \rightarrow FeCl_2 + Cu$
2) N.R.
3) $3Ba + Ni_3(PO_4)_2 \rightarrow Ba_3(PO_4)_2 + 3Ni$
4) $3Pb + 4Au(NO_3)_3 \rightarrow 3Pb(NO_3)_4 + 4Au$
5) $2Li + 2HOH \rightarrow 2LiOH + H_2$
6) $K + AgCl \rightarrow KCl + Ag$
7) N.R.
8) N.R.
9) $Fe + Cu(OH)_2 \rightarrow Fe(OH)_2 + Cu$