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Physical and Chemical ChangesPure SubstancesMixturesStates of MatterMatterEverything that has mass and volume is called matter.What is matter?

2Basic definition of matter.Lawof Conservation of MatterThere is no observable change in the quantity of matter during a chemical reaction or a physical change.

In other words, matter cannot be created nor destroyed. It is just converted from one form to another

3Definition of Conservation of matter.SolidsHave a definite shapeHave a definite volumeParticles of solids are tightly packed, vibrating about a fixed position.

LiquidsHave an indefinite shapeHave a definite volumeParticles of liquids are tightly packed, but are far enough apart to slide over one another.

GasesHave an indefinite shapeHave an indefinite volumeParticles of gases are very far apart and move freely.

Changing States of Matter

All matter, regardless of state, undergoes physical and chemical changes. These changes can be microscopic or macroscopic.

What kind of change does matter undergo?

Properties of MatterMeasuring MatterHow can we measure matter?

What equipment would we need?

Mass and WeightAre they the same?

What happens to our mass and weight if we were to go to the moon?

If two substances have the same weight, do they have the same mass?Measuring MassMass: Amount of substance

How can we measure mass?Scale or balance

What are the units of mass?Grams (or pounds)

Measuring VolumeVolume: Amount of space a substance takes up

How can we measure (or calculate) volume?measuring cup, graduated cylinder, (ruler)

What are the units of volume?mL, L, cm3, in3

Water DisplacementVolume = change in water levelVolume of water with object volume of water alone

If two substances have the same volume, will they displace the same amount of water?

Do We Have Gold?How could we use mass and volume to prove if our golden penny is really gold?Discover DensityDensity: How much stuff is in a certain spaceD= m/VmDVTo determine the density of a substance, divide its mass by its volume.

To solve for volume, divide mass by density.

To solve for mass, multiply density by volume.

Properties of MatterWhat is a physical change?A substance changes state but does not change its chemical composition. For example: water freezing, cutting a piece of wood The form or appearance has changed, but the properties of that substance are the same

18Definition of physical changes.What are chemical changes?A substance changes into something new. Occurs due to heating/chemical reaction The common signs of a chemical change are: Bubbles formingHeat is given off, or taken inMass changedColor change

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19Definition of chemical change.Physical and chemical properties may be intensive or extensive.

Intensive and Extensive Propertiesintensive properties do not depend on the size of the sample of matter and can be used to identify substances. DensityColor Boiling PointMelting PointWhat are intensive properties?

extensive properties DO depend on the quantity of the sample.MassvolumeWhat are extensive properties?Physical properties are those that we can determine/observe without changing the identity of the substance we are studying. Examples: Hardness, color, density, melting/boiling point

How can we identify physical properties?Chemical properties describe the way a substance can change or react to form other substances. Any of a materials properties that become evident during a chemical reactionIn other words, we have to define chemical properties of a substance by the chemical changes it undergoesthe substances internal structure must be altered for these properties to be observedEx: Heat of combustion, reactivity w/ waterWhat are chemical properties?

Comparison of Physical and Chemical PropertiesWhat are "substances"?Substances can be identified as either an element, compound, or a mixture.

Compounds

Can be decomposed into simpler substances by chemical changes, always in a definite ratio (combo of two or more elements)H2O ; H2O2 Hydrogen ; OxygenElements

Cannot be decomposed into simpler substances by chemical changesWhat is a pure substance?

27The two categories of pure chemical substances.Fixed compositionCannot be separated into simpler substances by physical methods Ex: You cant separate the H from the O in H2O2 without a chemical changeCan only be changed in identity and properties by chemical methodsProperties do not vary

Characteristics of Pure Substances

28Basic characteristics of pure substance:What is a mixture?Mixtures are two or more substances that are NOT chemically combined Can be separated by physical means or chemical means (sometimes) ; i.e. Sieve (physical) or Column Chromatography (chemical)Mixtures do not: Have constant boiling points Have constant melting points

Have variable composition

Components retain their individual characteristic properties (i.e. Sand/Salt Mixture: sand and salt retain their individual BPs, MPs, etc.)

May be separated into pure substances by physical or chemical methods Mostly PHYSICAL

Mixtures of different compositions may have widely different propertiesEX: imagine a handful of M&Ms as an examples or a handful of different types of beans:Characteristics of Mixtures

30Basic identification of a mixture.Have the same composition throughoutComponents are indistinguishableLiquid: Looks like a single, uniform liquidSolid: An Alloy Stainless steel(Iron, Chromium, others)May or may not scatter lightExamples: Kool-Aid, shampoo, etc.

Homogeneous Mixtures

31Brainstorm more examples of homogenous mixtures.What are solutions?Solutions are homogeneous mixtures that do not scatter light. (exception: COLLOIDS)Created when something is completely dissolved in pure water. Therefore, they are easily separated by distillation or evaporation.Examples: Kool-Aid, salt water

What are colloids?Colloids are solutions. Substance that is microscopically dispersed in another substance They can be described as a substance trapped inside another substance They can be identified by their characteristic scattering of light.For example: jello, fog, smoke, milk, vanilla yogurt

Milk a colloid of liquid butterfat globules dispersed within a water-based solution

33Brainstorm more ideas of colloids: fog, egg merangue, jello, smoke, etc.Do not have same composition throughoutComponents are distinguishableExamples: fruit salad, vegetable soup, etc.Heterogeneous Mixtures

34Brainstorm more examples of heterogenous mixtures.What are Suspensions?Suspensions are mixtures that do not stay mixed The solute settles or can be filtered out Examples: lava lamp, snow globes

Table 2.1 (pg 40)SubstanceStateColorM.P. (C)B. P. (C)NeonGascolorless-249-246OxygenGasColorless-218-183ChlorineGasGreenish-yellow-101-34EthanolLiquidColorless-11778MercuryLiquidSilvery-white-39357BromineLiquidReddish-brown-759WaterLiquidColorless0100SulfurSolidYellow115445Sodium chlorideSolidWhite8011413GoldSolidYellow10642856CopperSolidReddish-yellow10842562Color, MP & BP all physical and intensive properties. What does this tell you?? That when we identify unknown compounds, intensive & physical properties will be the most useful to us in identification!!!37