1 Chap 1 Section 2- Describing Matter Characteristics of matterThe SI system – units of measurementConversion of the units and calculationIdentify physical and chemical properties.
2 Matter Cloud Gravity Apple Student Electron Carbon dioxide Heat Fire AirTreesAtomGravityStudentCarbon dioxideFireMoleculeDreamDrop of water
3 Matter All matter have physical properties. Matter has Volume, Mass and Density.Volume – the space the object occupies.Mass – the quantity of matter.Density – the ratio of mass to volumeHow to measure and calculate?What is the units of these physical properties
4 Systems of UnitsSI System: The international system of units established by the International Committee on Weights and Measures. Such units are based on strict definitions and are the only official units for physical quantities.US Customary Units (USCU): Older units still in common use by the United States, but definitions must be based on SI units.
5 SI (System International Unit ) Chapter 1SI (System International Unit )
7 Units for Chemistry Quantity SI unit USCS unit Mass kilogram (kg) In Chemistry we use only a few fundamental quantities: mass, volume, and mole etc. An additional quantity, density is derived from some of above units.QuantitySI unitUSCS unitMasskilogram (kg)slug (slug)VolumeCubic meter( )Cubic footTemperatureCelsius ( )Fahrenheit (F)Amount of substanceMole
8 SI systemWhen working with numbers, be careful to distinguish between a quantity and its unit. Quantity describes something that has magnitude, size, or amount. Unit is a quantity adopted as a standard of measurement.
9 Base units can be too large or too small for some measurements, so the base units may be modified by attaching prefixes.
10 Procedure for Converting Units Write down quantity to be converted.Define each unit in terms of desired unit.For each definition, form two conversion factors, one being the reciprocal of the other.Multiply the quantity to be converted by those factors that will cancel all but the desired units.
11 Example 1: Convert 12 in. to centimeters given that 1 in. = 2.54 cm. Step 1: Write down quantity to be converted.12 in.Step 2. Define each unit in terms of desired unit.1 in. = 2.54 cmStep 3. For each definition, form two conversion factors, one being the reciprocal of the other.
12 Example 1 (Cont. ): Convert 12 in. to centimeters given that 1 in. = 2 Example 1 (Cont.): Convert 12 in. to centimeters given that 1 in. = 2.54 cm.From Step orStep 4. Multiply by those factors that will cancel all but the desired units. Treat unit symbols algebraically.Wrong Choice!Correct Answer!
13 Practice problems Let’s do some example problem together Convert 2.53 mL to LitersConvert 1258 cm to metersConvert 15 g to kilogramsPage 14# 1-3 work with your partner who is sitting next to you.
14 Properties of Matter Physical Properties A physical property of a substance is a characteristic that does not involve a chemical change.Physical properties of a substance can be determined without changing the nature of a substance.
15 Properties of matter Physical properties Physical properties describe a matter. One of properties is Density.
16 Concept Map of Density Mass Volume Units for volume of a regular solid the amount of matter something hasBalance or scaleWater displacementgraduated cylinderGram ml mlUnits for volume of an irregular objectthe amount of space something takes upUnits for volume of a liquidOf an irregular object is measured byL x W x HUnits for mass
17 Properties of Matter, continued The density of a substance is the same no mater what the size of the sample is.
18 ExampleFind the density of sulfuric acid if 15 cm3 has a mass of 27.6 g.Unknown density of sulfuric acid dataV = 15 cm3M = 27.6 gD = M/V27.6g / 15 cm3 = 1.84 g/cm3
19 Practice problemsFind the density of a block of metal which is 16 mm long, 12 mm wide and 5 cm high. The mass of this block is mg.Find the mass in grams of a bar of silver 6 cm long, 10 cm wide and 4 cm high. Silver has a density of 10.5 g/cm3Find the volume of a container necessary to hold 200 g of mercury. The density of mercury is g/cm3.
20 Properties of Matter, continued Chemical Properties A chemical property a property of matter that describes a substance’s ability to participate in chemical reactions.A chemical property of many substances is that they react with oxygen.example: rustingSome substances break down into new substances when heated.