Double Displacement Examples: 47 Problems with Answers

Start with the recap, study the fully worked examples, then use the practice problems to check your understanding of Double Displacement.

This page combines explanation, solved examples, and follow-up practice so you can move from recognition to confident problem-solving in Chemistry.

Concept Recap

A double displacement (or metathesis) reaction occurs when two ionic compounds in solution exchange partners: AB + CD → AD + CB.

Two couples swap partners at a dance — each positive ion pairs with the other's negative ion.

Read the full concept explanation →

How to Use These Examples

Read the first worked example with the solution open so the structure is clear.
Try the practice problems before revealing each solution.
Use the related concepts and background knowledge badges if you feel stuck.

What to Focus On

Core idea: Double Displacement starts by comparing the reactant-product pattern, charges, states, and conserved atoms.

Common stuck point: Students often know a formula related to double displacement but skip the recognition step: Does the balanced equation match a recognizable pattern of reactants, products, ions, oxygen, or electron transfer? That leads to a correct-looking substitution attached to the wrong chemical model.

Sense of Study hint: Ask: Does the balanced equation match a recognizable pattern of reactants, products, ions, oxygen, or electron transfer?

Worked Examples

Example 1

easy

Write the balanced equation for the reaction between sodium chloride and silver nitrate solutions.

Answer

NaCl + {AgNO}_{3} \to {NaNO}_{3} + AgCl ↓

First step

Double displacement:

\text{AB} + \text{CD} \rightarrow \text{AD} + \text{CB}

(cations switch partners).

Full solution

2
$\text{NaCl} + \text{AgNO}_3 \rightarrow \text{NaNO}_3 + \text{AgCl}$ .
3
AgCl is insoluble (precipitate ↓). The equation is already balanced: 1 of each element on each side.

Double displacement (metathesis) reactions occur when the exchange of ions produces an insoluble precipitate, a gas, or water. Solubility rules help predict whether a precipitate will form.

Example 2

medium

Predict the products and write the balanced equation:

\text{BaCl}_2 + \text{Na}_2\text{SO}_4 \rightarrow ?

Predict the products of the double displacement reaction

Example 3

medium

Predict and balance:

\text{AgNO}_3 + \text{Na}_2\text{S} \rightarrow

Predict the products and balance the equation

Example 4

medium

Identify the precipitate when

\text{Pb(NO}_3)_2

(aq) is mixed with

\text{KCl}

(aq), and write the balanced equation.

Example 5

hard

Mix 100 mL of 0.20 M Pb(NO

_3

)

_2

with 100 mL of 0.40 M KI. Find moles of PbI

_2

(

M=461

) and limiting reactant.

Practice Problems

Try these problems on your own first, then open the solution to compare your method.

Example 1

easy

Classify:

\text{HCl} + \text{NaOH} \rightarrow \text{NaCl} + \text{H}_2\text{O}

Example 2

hard

When solutions of lead(II) nitrate and potassium iodide are mixed, a bright yellow precipitate forms. Write the balanced molecular equation, identify the precipitate, and explain how to predict which product is insoluble.

Write the balanced molecular equation and identify the precipitate

Example 3

easy

Classify:

AgNO_3 + NaCl \rightarrow AgCl + NaNO_3

. What type?

Example 4

easy

Complete the partner swap:

BaCl_2 + Na_2SO_4 \rightarrow

Example 5

easy

Which is double displacement? (a)

Zn + 2HCl \rightarrow ZnCl_2 + H_2

(b)

KOH + HCl \rightarrow KCl + H_2O

Example 6

easy

AB + CD \rightarrow AD + CB

, which ions pair up in the products?

Example 7

easy

Complete:

HCl + NaOH \rightarrow

? (acid-base neutralization)

Complete the acid-base neutralization (double displacement)

Example 8

easy

Two ionic compounds in solution exchange partners. Name the type.

Example 9

easy

Complete:

Pb(NO_3)_2 + 2KI \rightarrow

Example 10

easy

If both products of a swap are soluble and no gas/water forms, what happens?

Example 11

medium

Balance and predict:

CaCl_2 + Na_3PO_4 \rightarrow

Balance the equation and predict products

Example 12

medium

Predict products and balance:

FeCl_3 + NaOH \rightarrow

Example 13

medium

Does

NaCl + KNO_3

react? Use solubility (both products soluble).

Example 14

medium

Balance:

Al_2(SO_4)_3 + BaCl_2 \rightarrow AlCl_3 + BaSO_4

Supply the missing coefficients to balance the equation

Example 15

medium

Identify whether

H_2SO_4 + 2KOH \rightarrow K_2SO_4 + 2H_2O

is double displacement.

Example 16

medium

Predict and balance:

(NH_4)_2S + Cd(NO_3)_2 \rightarrow

Example 17

medium

Why does mixing

AgNO_3

and NaCl react but mixing

NaNO_3

and KCl does not?

Example 18

medium

Complete and balance:

K_2CO_3 + CaCl_2 \rightarrow

Example 19

medium

Predict and balance:

AgNO_3 + KCl \rightarrow

Example 20

challenge

Mixing 0.10 mol

BaCl_2

with 0.10 mol

Na_2SO_4

: mol

BaSO_4

(M=233) precipitate and its mass?

Example 21

challenge

0.20 mol

Pb(NO_3)_2

reacts with excess KI. Mass of

PbI_2

(M=461) formed?

Example 22

challenge

Mixing 0.30 mol AgNO3 with 0.20 mol NaCl: which limits AgCl, and how many mol form?

Example 23

easy

Complete:

\text{KOH} + \text{HNO}_3 \rightarrow

Example 24

easy

Classify:

\text{Na}_2\text{S} + \text{ZnCl}_2 \rightarrow 2\text{NaCl} + \text{ZnS}

Example 25

easy

List three driving forces that make a double displacement reaction go forward.

Example 26

easy

Complete:

\text{Na}_2\text{CO}_3 + 2\text{HCl} \rightarrow

Example 27

easy

Mixing

\text{KNO}_3

(aq) and

\text{NaCl}

(aq). Does a reaction occur?

Example 28

medium

Balance:

\text{Ba(OH)}_2 + \text{H}_3\text{PO}_4 \rightarrow \text{Ba}_3(\text{PO}_4)_2 + \text{H}_2\text{O}

Balance the equation: Ba(OH)₂ + H₃PO₄ → Ba₃(PO₄)₂ + H₂O

Example 29

medium

Predict products:

\text{CuSO}_4 + 2\text{NaOH} \rightarrow

Example 30

medium

Does mixing

\text{KCl}

and

\text{NaOH}

give a precipitate?

Example 31

medium

Balance:

\text{Mg(NO}_3)_2 + \text{Na}_3\text{PO}_4 \rightarrow \text{Mg}_3(\text{PO}_4)_2 + \text{NaNO}_3

Supply the missing coefficients to balance the equation

Example 32

medium

\text{HCl} + \text{NaHCO}_3 \rightarrow \text{NaCl} + \text{H}_2\text{O} + \text{CO}_2

, what is the driving force?

Example 33

medium

Predict and balance:

\text{NH}_4\text{Cl} + \text{NaOH} \rightarrow

Example 34

medium

Predict whether

\text{NaCl}

(aq) +

\text{AgNO}_3

(aq) reacts. If so, write the net ionic equation.

Example 35

medium

Balance:

\text{H}_3\text{PO}_4 + 3\text{NaOH} \rightarrow

Example 36

hard

How many grams of AgCl (

M=143.3

) precipitate when 0.50 mol AgNO

_3

reacts with excess NaCl?

Example 37

hard

50.0 mL of 0.100 M BaCl

_2

is mixed with 50.0 mL of 0.100 M Na

_2

_4

. What mass of BaSO

_4

(

M=233

) precipitates?

Example 38

hard

25.0 mL of 0.200 M HCl is titrated to neutral by NaOH of unknown concentration. If it takes 20.0 mL of NaOH, find the NaOH concentration.

Example 39

hard

Why does adding HNO

_3

to NaCl (solid) sometimes release HCl gas (if concentrated)? Identify the driving force.

Example 40

hard

Why is the reaction

\text{CaCl}_2 + 2\text{NaCl} \rightarrow \text{CaCl}_2 + 2\text{NaCl}

NOT a double displacement reaction?

Example 41

challenge

A 4.66 g sample of AgCl (

M=143.3

) forms from excess NaCl(aq) added to AgNO

_3

(aq). Find the molarity of original 50.0 mL AgNO

_3

solution.

Example 42

challenge

Mixing 25.0 mL of 0.10 M AgNO

_3

with 25.0 mL of 0.040 M Na

_2

CrO

_4

gives Ag

_2

CrO

_4

precipitate (

M=331.7

). Find limiting reactant and mass of precipitate.

← Back to Double Displacement Practice Mode

Related Concepts

Chemical Reaction Precipitation Reaction Net Ionic Equation

Background Knowledge

These ideas may be useful before you work through the harder examples.

chemical reaction