Presentation on theme: "Physical versus Chemical Properties"— Presentation transcript:
1 Physical versus Chemical Properties Chapter 2 Section 2Describing matter
2 Reviewing MATTER Matter: anything that has mass and takes up space Mass – the amount of matter in somethingVolume – the amount of space something occupiesWhich of the following is matter?A car?A box?You?
3 What is a property?Property: a characteristic of a substance that can be observed
4 Physical PropertyPhysical property: a property that can be observed without changing the identity of the substance.Examples:lustermalleability: the ability to be hammered into a thin sheetductility: the ability to be stretched into a wiremelting pointboiling pointdensitysolubilityspecific heat
5 Physical Properties Color Shape Size Density Melting Point Boiling Point
6 Example of Physical Property The physical properties of sodium metal can be observed or measured. It is a soft, lustrous, silver-colored metal with a relatively low melting point and low density.Hardness, color, melting point and density are all physical properties.
7 Special Physical Properties Melting point: the temperature at which a substance changes from a solid to a liquid at a given pressurewater = 0oCBoiling point: the temperature at which a substance changes from a liquid to a gas at a given pressurewater = 100oC
13 Density Density is the amount of mass per unit of volume. Density can be used to identify a substance.The density of water is 1.0g/mL
14 Density Calculations Calculations: D = m/VEx: A cube has a mass of 2.8 g and occupies a volume of 3.67 ml. Would this object float or sink in water?Mass = 2.8 g Volume = 3.67 mLD = 2.8g/3.67 mL= 0.76 g/mLThis object would float in water because its density is less than water (1.0 g/mL).
15 More Density Calculations Ex: A liquid has a mass of 25.6 g and a volume of 31.6 mL. Use the table below to identify the substance.M=25.6 g V=31.6 mLD = 25.6 g/31.6 mLD= 0.81 g/mLThe substance is ethanol.
16 Physical ChangePhysical change is the change that affects one or more physical properties of a substance.Imagine breaking a piece of chalk into two pieces. What are you changing? What is not being changed?Physical changes do not change the identity of the matter involved
17 Physical Change Freezing water for ice cubes Sanding a piece of wood Cutting your hairCrushing an aluminum canBending a paper clipMixing oil and vinegar
18 Chemical ChangeChemical change happens when two or more substance are changed into one or more new substances with different properties.Properties of a substance describe which chemical changes will or will not happenChemical change and properties are not the same, a change is the process in which it changes
19 Chemical Change Examples of Chemical Changes Soured milk Effervescent tabletsStatue of LibertyBaking a cake
20 Chemical Change Clues that chemical change has occurred Changes in colorHeatFizzing and foamingProduction of sound or light