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difference between pure substance and mixture

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Question:Which of the following substances are pure substances and which are mixtures? 1.sea water 2.cooking oil 3.coal 4.steel 5.chili sauce 6.bronze 7.sand 8.Gold 9. orange squash 10.Salt 11.Milk 10.Oxygen 12.Air 13.Oranger juice 14.Coke 15.Soil Plz tell me how did u find out that which substances were pure and which were mixtures. (If u help me i will be thankful to u all) thanx to all and special thanx to professor beatz and quiepe

Answers:Here's a hint: mixtures can always be broken down into other things. 1. Sea water is a mixture because it has a ton of different things in it, like salt and water and various microorganisms. 2. Cooking oil is a mixture. It is a blend of various kinds of oils. 3. Coal is a pure substance. It is made up of nothing but carbon atoms, pure to the atomic level. 4. Steel is a mixture. It is an alloy of different other metals, especially iron. It also uses carbon. 5. Chili sauce has all sorts of ingredients. I don't know what they are exactly, but there has to be stuff like different peppers and condiment bases. It's definitely a mixture. 6. Bronze is a mixture. It's another metal alloy made with tin, copper, and some other metals. 7. Sand is a mixture. I live by the beach, and you can see variations in the grains' colors. They're not all the same, so it's a mixture of different kinds of sand. 8. Gold is an element. At 24 k, it's as pure as you need to be for practical purposes. Pure substance. 9. Orange squash: well, it's all orange squash, but squash has the stem, the skin, the flesh, and all these different parts. The components themselves range from DNA to proteins to sugars and carbohydrates and other organic molecules. Mixture. 10. Salt is pure. Just NaCl, baby. 11. Milk has fats and proteins and carbs and water and vitamins. Mixture. 10. Oxygen is just oxygen, an element. Pure substance. 12. Air is a mixture of nitrogen, oxygen, carbon dioxide, water vapor, noble gases, and hydrogen. 13. "Oranger" juice: same as milk, for the most part. Mixture. 14. Coke: caffeine, carbonic acid, sugars... mixture 15. Soil has all sorts of stuff in it. Mixture.

Question:A. A pure substance has equal amounts of matter in its composition. A mixture has varying amounts of matter in its composition. B. A pure substance may be homogeneous or heterogeneous in composition. A mixture is only heterogeneous in composition. C. A pure substance contains matter that may or may not be in uniform composition. A mixture contains a variety of different substances mixed together. D. A pure substance contains only one type of matter. A mixture contains two or more kinds of matter that may or may not be in uniform composition.

Answers:D looks like the best answers. A pure substance is any substance that can not be separated by a chemical or physical process (i.e. pure gold).

Question:Would they be the same? Can a pure substance be made up of compounds?

Answers:A pure substance is an element or compound. If it's an element, then it's made of only one kind of atom. If it's a compound, then it's made of only one kind of formula unit. For example, hydrogen (H2) and oxygen (O2) are elements. In pure samples of H2 and O2, you find only one kind of element. H2O is a compound, water. In pure samples of H2O, you find only formula units of H2O (called molecules because H2O is covalent). Neither the components that make up H and O atoms, nor the atoms that make up H2O can be separated by physical means. H2, O2, and H2O are all considered substances. A mixture is a combination of substances. Unlike a substance, mixtures CAN be separated into their component substances by physical means. If you dissolve table salt (NaCl) in a glass of water, that's an example of a mixture. The water can be separated from the salt by boiling it away, which is a physical change, not a chemical change. A homogeneous mixture is one in which the two components are evenly mixed and appear to be one phase. Saltwater is an example, because although it is made of up different substances, they appear to be one. Chicken soup is an example of a heterogeneous mixture (or a mixture in which the components are not in one phase) because you can easily distinguish the bits of chicken, noodles, and broth in the mixture. So to summarize: substances and mixtures are NOT the same, a pure substance CAN be a compound (or it can be an element), and mixtures CAN be made from different compounds. I hope that helps. Good luck!

Question:In my chemistry book, a pure substance is defined as "matter with distinct properties and composition that doesn't vary from sample to sample." A homogenous mixture is "a mixture uniform throughout." It later says that if matter is uniform throughout it's homogenous, if it DOES have variable composition, it is a homogenous mixture (or a solution), and if it DOES NOT have variable composition, it's a pure substance. I'm not seeing how this makes sense... help?!

Answers:Think of it as a pure substance is like an element, the element is always the same. Every time, Carbon is going to have the same properties. A homogeneous mixture is when two things are combined and you can not see any difference. The example i like is water and sand. When you put the sand in the water, it doesn't mix so the mixture is heterogeneous. If you mix water and sugar; however, the end product is still aqueous and appears uniform. It will be this way until you get into over saturation.

From Youtube

Differentiate Between Pure Substances and Mixtures :Learn how to differentiate between pure substances and mixtures

Mixtures :Teachzer.com - This video discusses the differences between mixtures and compounds. It also goes through the different methods in separating mixtures into the individual substances.