Salt water is a homogeneous mixture

Big Bang HTL 2, textbook

Basics of Chemistry (2nd year, 3rd semester) 11 Substances 1 Tab. 1.1 and 1.2 provide an overview of different types of mixtures. Table 1.1: Homogeneous mixtures: Consists of 1 phase Name of the mixture Components Example Solution Solid dissolved in liquid Salt water Liquid dissolved in liquid Alcohol in water Gas dissolved in liquid Oxygen in water Alloy Solid in solid bronze (copper + tin) Gas mixture Gas in gas Air Tab. 1.2: Heterogeneous mixtures: Consists of 2 or more phases (F16) Name of the mixture Components Example Mixture solid + solid Rock, e.g. granite suspension solid in liquid sludge, paint, smoke, solid in gas, exhaust gases, soot in air, emulsion, liquid in liquid Milk (fat in water), salad marinade Fog Liquid in gas Fog, clouds Fig. 1.13: Pure substance: gaseous Fig. 1.14: Mixture: 2 components liquid And what does it look like in the atomic range? In Figures 1.13 and 1.14 there are two model drawings showing mixtures and pure substances. You should be able to read the following from these example drawings: - is it a pure substance or a mixture? - How many components does a possibly represented mixture consist of? (1 type of particle 1 component) - which states of aggregation occur? Summary Homogeneous mixtures look uniform and consist of only 1 phase. Examples: Salt water, air Heterogeneous mixtures look inconsistent and consist of 2 or more phases. Examples: rocks, fog Phases in chemistry The term phase may be confusing at the beginning, because otherwise phase is only known as a term for periods of time. In chemistry, however, phase denotes a uniform area of ​​matter. A water-oil mixture therefore consists of 2 phases, namely a water phase and an oil phase (and this completely regardless of how long the two remain mixed!) I Z Of emulsions and emulsifiers (F15) Emulsions are mixtures, who “don't like to remain mixed”, i.e. have a tendency to separate again, such as B. Oil and water. If you want a stable mix, there is a “trick”. So-called emulsifiers are added, these are substances that ensure that an emulsion remains stable, i.e. does not separate again. The lecithins are important emulsifiers in industry. Lecithins occur very frequently in nature, where they also act as emulsifiers. For example in the egg yolk, which is a mixture of fats, proteins and water. There, too, lecithins ensure that the fat does not float on the top but everything stays well mixed. Lecithins are used as a food additive e.g. B. used in margarine. Margarine is a mixture of different fats, water and salt. These emulsifiers are added so that fat and water do not separate again. Lecithins are also often found in chocolate, baby milk powder and ice cream. i Fig. 1.15: Emulsifier and stable emulsion Basic substances and mixtures of substances Indicate whether they are pure substances or mixtures! Give reasons for your opinion and name the respective mixture with its correct name: copper, freshly squeezed orange juice, milk, carbon dioxide, brass, ink, sea water, aluminum, rum, mineral water, garden soil, effervescent powder L Define the following terms: mixture, pure substance, component , Phase, homogeneous, heterogeneous, solution, emulsion L Describe the models shown according to the following criteria: Basic substance / mixture Number of components Physical state L 1.3 F17 A2 F18 A1 Fig. 1.16: Fig. 1.17: F19 A1 For testing purposes only - property of the publisher öbv

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