Chemistry problems with answers
Chemistry problems on STEMinute focus on the calculations and reasoning behind the subject: moles and masses, limiting reagents, gas laws, concentrations and pH, atomic structure and reactions. The numbers are chosen so you can work them out by hand. A reliable routine is to write the balanced equation, convert everything to moles, apply the ratio from the equation, and convert back to the unit the question asks for. Try each day's round first, then read the answers and the main steps below.
All Chemistry days
Oct 15, 2026
- Diluting a solution
- Boiling off water
- Warming a gas
Oct 14, 2026
- Reading a burette
- Water from hydrogen
- Adding a catalyst
Oct 13, 2026
- Moles of water
- A gas under a piston
- A lime kiln
Oct 12, 2026
- Neutrons in sodium
- Oxygen to burn methane
- Blending two salt solutions
Oct 11, 2026
- Atoms in five units
- Gas volumes in a reaction
- Carbon dioxide from carbon