Mixtures tend to retain some of the properties of their individual substances. But the properties of a mixture are less constant than the properties of a substance. The properties of a mixture can vary because the composition of a mixture is not fixed. The type of pepper and the quantity of pepper used in a salsa recipe determine the "hotness" of a batch of salsa. Chili peppers contain a compound called capsaicin (C18H27NO3) that can cause a burning sensation in your mouth. The amount of capsaicin varies among types of peppers. Cayenne peppers, for example, contain more capsaicin than do jalapeño peppers.
No matter how well you stir a batch of salsa, the ingredients will not be evenly distributed. There may, for example, be more onion in one portion of the sala than another. Mixtures can be classified by how well the parts of the mixture are distributed throughout the mixture.
If you look at a handful of sand from a beach, the sand appears to be all the same material. However, if you use a hand lens, you will notice that the sample of sand is not the same throughout. Grains of sand vary in size. Also, some grains are light in color and some are dark. Sand is an example of a heterogeneous mixture. Heterogeneous comes from the Greek words hetero and genus meaning "different" and "kind." In a heterogeneous mixture, the parts of the mixture are noticeably different from one another.
If you collect water from both the shallow end and the deep end of a swimming pool, the water samples will appear the same. The water is a swimming pool is a homogeneous mixture of water and substances that dissolve in water. In a homogeneous mixture, the substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another. A homogeneous mixture appears to contain only one substance. A serving spoon is made of stainless steel - a homogeneous mixture of iron (Fe), chromium (Cr), and nickel (Ni).