MATTER AND MEASUREMENTQBA Miguel A. Castro Ramírez
THE STUDY OF CHEMISTRY Matter: Anything that has mass and takes up space. Atoms: The building blocks of matter. Property: Any characteristics that allows us to recognize a particular type of matter andto distinguish it from other types Elements: Substance that cannot be broken down into simpler substances by chemical rxns. E.g. O, N, C and P : Made of the same kind of atom. Compound: Made of two or more different kinds of elements.
CLASSIFICATION OF MATTER 1) PHYSICAL STATE (States of Matter) GAS (Vapour) LIQUID SOLID Observable Properties No fixed volume Distinct volume Definite volume Can be compressed to independent of container Definite shapeoccupy smaller volume Shape depends on the Cannot be compressed Can be expand to occupy containerlarger volume Cannot be compressed Molecular Level Molecules are far apart Molecules: Packed closely Molecules: Tightly Speed : Very fast together but still move rapidly together Compressing: Decreases The rapid movement Definite arrangementspace increases frequency molecules to slide each Can only wiggle eachof collisions but doesn’t alter other easy to pour otherthe size/shape of the molecule
CLASSIFICATION OF MATTER 2) COMPOSITION Pure Substances: Matter that has distinct properties and a composition that does not vary from samples to samplesElement Mixture- Cannot be Compound - Combination of two or decomposed into - Subtances that more subtances in simpler substances composed of 2 or which each subtances- Composed only 1 kind retains its own more different atoms of atom chemically joined chemical identity together
CLASSIFICATION OF MATTER ELEMENTS COMPOUNDS MIXTURES The symbol of each Elements can interact with Each substance in a mixtureelement consist of 2 letter, other elements to form retains its own chemicalwith first letter capitalized compounds. identity and its own property.e.g; C,Al,Br,Cu,Hg H2 + O2 H2O Composition of mixture can In periodic table of H2O H2 + O2 be vary.elements The observation that the Components : Subtances elemental composition of a making up mixture. pure compound is always the Homogeneous: Uniform same: Law of Constant throughout e.g; Air- Composition=Law of definite homogenuos mixture of proportions gaseous subtances Pure compound has the Heterogeneous: Do not same elements and have same composition, composition & properties properties and appearance regardless the source. throughout. E.g; rocks and wood.
PROPERTIES OF MATTER Physical Properties- Those which the substance shows by itself without interacting withanother substance- Melting point, boiling point, density Chemical Properties-Those which the substance shows as it interacts with, or transforms into,other substances- Such as flammability, corrosiveness Intensive Properties- Do not depend on the amount of the sample being examined- Temperature, melting point and density Extensive Properties-Depends on the quantity of the sample with two examples being massand volume- Mass and volume
PROPERTIES OF MATTER Physical Changes- Substances changes its physical appearance but not its composition.- Changes of state (evaporation of water) , temperature, volume, etc. Chemical Changes - Substance is transformed into a chemically different substance - Combustion, oxidation, decomposition, etc.
PROPERTIES OF MATTER Separation of Mixtures DISTILLATION CHROMATOGRAPHY -Distillation uses -This technique separates FILTRATION-In filtration solid differences in the boiling substances on the basis of points of substances to differences in solubility insubstances are separate a homogeneous a solventseparated from liquids mixture into its - Test food coloringsand solutions. components - Separation of salt and water
SCIENTIFIC METHOD The scientific method is simply a systematic approach to solving problems.• Scientific Law: Concise verbal statement or a mathematical equationthat summarizes a broad variety of observations and experiences.1. Hypothesis: tentative explanation/prediction concerning some phenomenon. i.e. an educated guess that can be tested2. Data: facts or measurements obtained through careful observation or made during an experiment3. Scientific laws: statements that identify patterns in a large collection of data4. Theory: Explains & predicts an observed phenomenon that can be further tested
UNITS OF MEASUREMENT (SI) Système International d’Unités (International System of Units) A different base unit is used for each quantity. SI Base Units1. Length – meter (m)*2. Mass – kilogram (kg)*3. Time – second (s)4. Amount of substance – mole (mol)5. Temperature – Kelvin (K)*6. Electric current – Ampere (A)7. Luminous intensity – candela (cd)• All measured quantities can be expressed in terms of these 7 base units
UNITS OF MEASUREMENT (Metric System)• Prefix used in metric system• To indicate decimal fractions or multiples of various unitsMultiple Decimal equivalent Prefix Symbol English109 1,000,000,000 giga- G billion106 1,000,000 mega- M million103 1,000 kilo- k thousand102 100 hecto- h hundred101 10 deca- da ten100 1 NA NA NA10-1 0.1 deci- d tenth10-2 0.01 centi- c hundredth10-3 0.001 milli- m thousandth10-6 0.000001 micro- µ (mu) millionth10-9 0.000000001 nano- n billionth10-12 0.000000000001 pico- p trillionth
UNITS OF MEASUREMENTLength and Mass- Unit SI for length = meter (m)- Mass: Measure of the amount of material in an object. - SI Unit= kilogram (kg) = 2.2 pounds (lb)Temperature- Measure of hotness or coldness of an object.- Physical property: determine the direction of heat flow- SI Unit: Kelvin (K): based on the property of gases -Zero Kelvin= -273.15 °C – lowest attainable temperature (absolute zero)- The Celsius (°C) scale is based on the properties of water. 0°C = 273.15 K is the freezing point of water 100°C = 373.15 K is the boiling point of water K= °C + 273.15- Fahrenheit (°F) : Common in US (not generally used in scientific studies) °C = 5/9 (°F-32) or °F = 9/5 (°C) +32
UNITS OF MEASUREMENT1) The temperature of the room is 75°F. What is its temperature in Celsius degrees?2) A child has a body temperature of 38.7°C.a)If normal body temperature is 98.6°F, does the child have afever?b)What is the child’s temperature in Kelvin?
UNITS OF MEASUREMENTDERIVED SI UNITS VOLUME Given by its length cubed, (length)3 cm3 : Frequently used in chemistry Another commonly used metric unitsfor volume are the liter (L)A liter (L) = dm3 = 1000mLA milliliter (mm) = 1cm3 Syringe, burets and pipets deliverliquids with more precision thangraduated cylinders.
UNITS OF MEASUREMENTDERIVED SI UNITS DENSITY Property of matter that is widely used to characterize a substance. Density: mass/volume Expressed in unit g/cm3 or g/mL. Densities are temperature dependent – because most substances change volume when they are heated or cooled. When reporting densities, temperature must be stated
UNITS OF MEASUREMENTCalculating Density from Mass and Length1) If a rectangular slab of Lithium (Li) has a mass of 1.49 x 10 3mg and has sides that measure 20.9 mm by 11.1 mm by 11.9mm, what is the density of Li in g/cm3 ?
UNCERTAINTY IN MEASUREMENTExact numbers: - Values are known exactly - 12 eggs in a dozen, 1000g in 1kgInexact numbers: - Values have some uncertainty - Obtained by measurement - equipment and human errors Uncertainties always exist in measured quantities PRECISION AND ACCURACYAccuracy : How closely individual measurementsagree with the correct or true value.Precision : Measure of how closely individualmeasurement agree with one another.
UNCERTAINTY IN MEASUREMENT Significant Figures Rules for counting sig figs1. Nonzero integers always count as sig figs2. There are 3 classes of zeroes: a. Leading zeroes are zeroes that precede all the nonzero digits. These DO NOT count as sig fig. e.g. 0.0025 b. Captive zeroes are zeroes b/w nonzero digits. These ALWAYS count. E.g. 1.006 c. Trailing zeroes are zeroes at the right end of the number. They are significant ONLY IF the number contains a decimal point. E.g. 1.00
UNCERTAINTY IN MEASUREMENT Rules of Significant Figures in Calculation• When addition or subtraction is performed, answers are rounded to the least significant decimal place. 12.11 +18.0 +1.013 = 31.123 to →31.1 corrected• When multiplication or division is performed, answers are rounded to the number of digits that corresponds to the least number of significant figures in any of the numbers used in the calculation. 4.56 x 1.4 =6.38 → .4 6 corrected to• BODMAS still applies – Bracket, Of, Division, Multiplication, Addition, Subtraction
UNCERTAINTY IN MEASUREMENTDetermining the Number of Significant Figures How many sig. fig in the given numbers below: (a) 0.1044 g (b) 0.0000007160 cm3 Determine the number of sig fig in the problem below: (a) 9.2 cm x 6.8 cm x 0.3744 cm (b) 865.9 – 2.8121
UNCERTAINTY IN MEASUREMENT Dimensional Analysis• We use dimensional analysis to convert one quantity to another.• Most commonly dimensional analysis utilizes conversion factors (e.g., 1 in. = 2.54 cm) 1 in. 2.54 cm or 2.54 cm 1 in.
UNCERTAINTY IN MEASUREMENT Use the form of the conversion factor that puts the sought-for unit in the numerator. desired unit Given unit × = desired unit given unit• For example, to convert 8.00 m to inches, – convert m to cm – convert cm to in. 100 cm 1 in. 8.00 m × × = 315 in. 1m 2.54 cm
UNCERTAINTY IN MEASUREMENTConverting Units of Lengtha) To wire your stereo equipment, you need 325 centimeters (cm) of speaker wire that sells for RM 0.15/ft. What is the price of the wire?- 1 in = 2.54 cm 1ft = 12 in SOLUTION: Length (in) = length (cm) x conversion factor = 325 cm x in = 128 in 2.54 cm Length (ft) = length (in) x conversion factor = 128 in x ft = 10.7 ft 12 in Price ($) = length (ft) x conversion factor = 10.7 ft x RM 0.15 = $1.60 ft
UNCERTAINTY IN MEASUREMENT Converting Units of VolumeWhen a small piece of galena, an ore of lead, is submerged in thewater of a graduated cylinder that originally reads 19.9 mL, thevolume increases to 24.5 mL. What is the volume of the piece ofgalena in cm3 and in L? volume (mL) before and after addition subtract volume (mL) of galena 1 mL = 1 cm3 1 mL = 10-3 L volume (cm3) of volume (L) of galena galena SOLUTION: (24.5 - 19.9) mL = volume of galena = 4.6 mL 4.6 mL x 1 cm 4.6 mL x 10 L 3 -3 = 4.6 cm 3 = 4.6x10-3 L mL mL