Ch 2.1 Properties Of Matter. Ch 2.4 Changes In Matter

Transcription

1 Ch 2.1 Properties Of Matter Ch 2.4 Changes In Matter

2 Matter is the part of the universe that has mass and volume and exists in three phases: Solid Liquid Gas Phase changes are NOT chemical changes!

3 Solid: Does not flow easily Definite (fixed) shape Definite (fixed) volume Particles are close together (thus not easily compressible)

4 Liquid: Flows easily. Definite shape (takes the shape of any container) Definite volume Little space between particles (thus not easily compressible)

5 Gas: Flows easily Takes the shape of the container Fills the volume of the container Particles are very far apart (thus, easily compressible)

6 Physical Changes

7 The process of boiling and freezing causes physical changes. I.g. water changes form but still remains the H 2 O compound. The change is in the form of a substance & not its chemical composition. H 2 O (s) = solid water H 2 O (l) = liquid water H 2 O (g) = gas water (water vapor) Physical Changes

8 Chemical Changes

9 Chemical reactions are chemical changes. It involves the rearrangement of atoms to produce new substances and chemical changes.

10 How do we know if matter is changing (chemistry occurring)? Observations to watch for: Permanent new state change (e.g. liquids to solid, ppt) Formation of gas bubbles Formation of light or flames Temperature change (e.g. gets colder or hotter) A color change A new odor

11 The first video will illustrate how O 2 gas and H 2 react to form water (chemical reaction) The second video will show how we can use this type of reaction s energy as a fuel source for the Space Shuttle

12 The Law Of Conservation

13 The Law of Conservation of Mass states that atoms are neither created nor destroyed Atoms are merely rearranged to create something new, with new chemical and physical properties

14 Let s observe the reaction movie on the next slide. Is the law of conservation of mass shown?

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16 Note the beakers before and after I d say the law of conservation of mass is shown

17 Parts Of A Chemical Equation

18 Reactants are the chemicals reacting Products are the chemicals produced

19 Use the + sign to separate chemicals Use the yield sign (Do NOT Use = equals sign)

20 To obey the Law of Conservation it must be balanced by adding coefficients mass of reactants = mass of products We will learn to balance equations later.

21 2.2 Mixtures Of Matter

22 There are two types of mixtures Mixtures can be Homogeneous or Heterogeneous

23 Homogeneous Mixtures

24 Homogeneous mixtures (a uniform mixture) has a composition that is the same throughout

25 Another name for homogeneous mixture is a solution For example a solute (salt) is mixed in a solvent (water) to produce salt water (the solution)

26 The next video segment will show how a solution is made

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28 The homogeneous mixture, the solution consists of the following: The solute is usually the smaller number and it gets dissolved The solvent is usually the bigger number and does the dissolving 2.18 g g

29 Remember: Solute + Solvent = Solution 2.18 g To finding percent mass: Solute mass x 100% Solution mass g 2.18 g x 100% 2.18 g g 2.18 g x 100% = 3.78% g 57.68g

30 Types of Solutions

31 Solutions don t have to be a solid solute dissolved in an liquid solvent. Gaseous solutions: For example Air = 80% N 2 and 20% O 2 Solid Solutions: For example door knobs = 67% Cu and 33 % Zn Solutions which consist of a gas solute dissolved in a liquid solvent: carbonated drinks = CO 2 and H 2 O

32 Homogeneous Mixtures

33 Heterogeneous mixtures (are non-uniform mixtures) they have different composition and properties and several components can be distinguished from one another This usually occurs when a solute is not soluble a solvent.

34 Separation of Mixtures

35 Separation of Mixtures Many different methods can be used to separate the components of a mixture from one another This involves a physical change NO chemical reaction is needed, substances are NOT bonded, just physically combined Here are a couple of methods that you may carry out in the laboratory

36 Decanting separates a liquid from a solid Filtration separates a liquid from a solid as well For example, filtering sand from saltwater

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38 Distillation Distillation: separates a solution by different boiling points Water is separated from the salt by heating the solution, minerals are left behind and the steam is condensed to pure water. This is how distilled water is made

39 g-word-water-desalination-video.htm Watch this video segment about distilling dirty water to produce clean water

40 Paper Chromatography Chromatography: separates a solution of different colors Here a strip of porous paper, such as filter paper, is dipped into a liquid, which travels up the paper, like a wick, and the ink mixture separates into its component colors

41 For chromatography the solute is the dye and the solvent is the water. You need to make sure that the solute and solvent are chemically similar so that the process of chromatography will work This is called solubility