A chemical reaction in which a single compound breaks down into two or more simpler substances (elements or simpler compounds), typically requiring an energy input.
The reverse of synthesis — taking apart a complex structure into simpler pieces.
Showing a random 20 of 50 problems.
Example 1
challenge
Heating 10.0 g CaCO3 (M=100) fully. Mass of CO2 released? (C=12,O=16)
Example 2
hard
Balance: Pb(NO3)2→PbO+NO2+O2.
Example 3
easy
A single compound breaks into two elements. Name the reaction type.
Example 4
medium
Explain why H2O2 decomposition can be classified as both a decomposition and a redox reaction.
Example 5
medium
Predict products of heating Ca(OH)2 (decomposition into oxide and water).
Example 6
easy
Complete and identify: 2HgO→ ? (decomposition)
Example 7
medium
How many grams of O2 are produced when 4.90 g KClO3 (M=122.5) fully decomposes? (2KClO3→2KCl+3O2)
Example 8
medium
Why does NaCl need electrolysis while H2O2 decomposes easily?
Example 9
medium
Why must thermal decomposition of NaCl use very high temperatures or electrolysis?
Example 10
medium
Decomposition of 2KClO3 gives 2KCl+ ____.
Example 11
hard
Distinguish decomposition from a combustion reaction using 2H2O2→2H2O+O2 and CH4+2O2→CO2+2H2O.
Example 12
medium
A catalyst is added to a decomposition. Does it change the products or the rate?
Example 13
medium
Decomposing 1 mol Al2O3 gives how many mol Al? (2Al2O3→4Al+3O2)
Example 14
hard
Decomposition of 50.0 g CaCO3 (M=100) yields how many grams of CaO (M=56)?
Example 15
challenge
NH4NO3 (M=80) decomposes to N2O (M=44) and water. If 16.0 g of NH4NO3 decomposes, what volume of N2O at STP forms? (22.4 L/mol)
Example 16
medium
Balance: NH3→N2+H2.
Example 17
easy
Is CaCO3→CaO+CO2 a decomposition reaction?
Example 18
medium
Distinguish: CaCO3→CaO+CO2 vs Zn+CuSO4→ZnSO4+Cu.
Example 19
hard
24.5 g KClO3 (M=122.5) decomposes completely. Volume of O2 at STP (22.4 L/mol)?
Example 20
easy
A decomposition reaction has ____ reactant(s) and ____ or more product(s).