I'm so confused. Is Copper II Nitrate a pure substance or a mixture? I think it's a pure substance, because isn't it a compound, and compounds are pure substances?, but it has more than one element in it, so would that make it a mixture? And if it is a pure substance, can it be heterogeneous? Can pure substances even be heterogeneous? I don't understand chemistry.And, if you could, please help me understand how to tell if something is a mixture or a pure substance. Thank you!
It helps to think about it all as a hierarchy beginning with elements. Elements are composed of atoms which all have exactly the same number of protons. Therefore, all the atoms have exactly the same chemical characteristics. NOTE: I was careful to restrict my definition to just protons. An element can have atoms whose numbers of neutrons vary. These are called isotopes, but they are still elements if the number of protons are all the same. This is why Uranium238 and Uranium235 are still the element Uranium. Each isotope has 92 protons. Compounds are composed of only 1 kind of molecule. Molecules are composed of atoms. Mixture is a vague term used to describe something which contains two or more compounds. Seawater is a mixture of the compounds water and salt. You and I are also mixtures. Most things on earth are mixtures. This definition is broken down further into homogeneous and heterogeneous mixtures. In a homogeneous mixture all the molecules or ions are evenly dispersed. Saltwater is a homogeneous mixture. In a heterogeneous mixture this is not the case. Chicken soup is a heterogeneous mixture. Copper (II) nitrate is therefore a compound. However, dissolved in water, it forms a mixture of water molecules and ions.
Copper II Nitrate might be a pure substance if it is pure. Copper II Nitrate IS a compound. Copper II Nitrate is not a mixture.
