Matter & chemistry
What makes rusting different from melting?
A chemical change produces substances with a different chemical identity.
Science & natureCategory
Matter & chemistry
Atoms, bonds, materials, and the changes behind everyday substances.
Matter & chemistry
Why clear salt water is still a mixture
Looking uniform does not make a material a pure substance.
Matter & chemistry
A measurement can be consistent and still be wrong
Precision concerns agreement between measurements; accuracy concerns agreement with the accepted value.
Matter & chemistry
Why is saltwater a mixture but water a substance?
A pure substance has a fixed composition; a mixture can vary.
Matter & chemistry
What does a chemical property tell you?
It describes how a substance can change into another substance.
Matter & chemistry
Which properties change when you double a sample?
An extensive property depends on how much material you have.