CHM 1045 General Chemistry and Qualitative Analysis Unit

CHM 1045: General Chemistry and Qualitative Analysis Unit 1 Introduction: Matter and Measurement Dr. Jorge L. Alonso Miami-Dade College – Kendall Campus Miami, FL Textbook References: • Module #1 Matter And Measurement

Scientific Method: A systematic approach to solving problems. Observation: the detection of a phenomenon by our sensory organs or their extensions (instruments). Scientist study CAUSE EFFECT Relationships Which factors affect the behavior of gasses? {Gas. Variables} η, P, V, & T Hypothesis: initial or tentative explanation of the causes of a phenomenon. Experiment: carefully designed hypothesis testing; done by controlling all the variables except your suspected CAUSE (independent variable, x) which is Matter And manipulated in order to observe its. Measurement EFFECT (dependent variable, y).

Experiment: carefully designed hypothesis testing; done by controlling all the variables except your suspected CAUSE (independent variable, x) which is manipulated in order to observe its EFFECT (dependent variable, y). V Dependent Variable 1 P OR V= k P Also, P↑V↓=k Boyle’s Law Independent Variable Law: concise verbal or mathematical summary for a variety of observations and experiences. Theory: a comprehensive explanation for natural phenomena that has withstood repeated analysis and experimentation. Kinetic Molecular Theory Matter And Measurement

What is the universe composed of? Matter: Anything that has mass and takes up space. Chemistry • Chemicals • Substances • Things Energy: the ability to perform an activity (work). • • Physics Kinetic (motion & heat) Electromagnetism (light, electricity & chemical bonds) Matter And Nuclear Measurement Gravity {Matter with Energy}

Chemistry: The study of matter and the changes it undergoes. Describing Matter: Physically and Chemically (1) Physical Properties (3) Chemical Properties (2) Physical Change (4) Chemical Change (reactions & equations) Matter And Measurement

Let’s get Physical! Physical Properties: The H 2 O (g) physical characteristics (appearance) of matter. H 2 O (s) State or phase (s, l, g), color, mass, volume, density, melting & boiling points, solubility, etc H 2 O (l) Physical changes occur without changes in the composition of matter. Physical change: H 2 O (s) H 2 O (l) Chemical change: 2 H 2 O (s) 2 H 2 (g) H 2 O (g) + O 2 (g) Physical Changes: Changes in the physical properties of matter. Changes of: state (s l g), density, temperature, shape, Matter volume, etc. And Measurement

Heat Energy & Phase (State) Changes (fusion) Matter And Measurement Phase Changes = Changes of State

Kinetic Energy & States of Matter Heat = Kinetic Energy Temperature c. pt. (condensation point) f. pt. (freezing point) m. pt b. pt. (melting point) (boiling point) Density (mass per unit volume) For H 2 O: m. pt. = f. pt = 0 OC b. pt. = c. pt = 100 OC For Methanol: m. pt. = f. pt = -98 OC b. pt. = c. pt = 65 OC {Kinetic. Molecular. Theory: Phase. Change} Matter And Measurement

Heating Curve: Energy & Phase Changes Heating water vapor Heating liquid water Heating solid ice Heat of Vaporization Heat of Fusion 0 OC For H 2 O: m. pt. = f. pt = For Methanol: m. pt. = f. pt = -98 OC b. pt. = c. pt = 100 OC b. pt. = c. pt = 65 OC Matter And Measurement

Let’s get Chemical! What happens when you add Na to water? K? {Na & K in H 2 O} Is this chemical or physical change? Chemical change is always accompanied by physical change! Chemical Properties: Can only be observed when a substance reacts and is changed into another substance. Does it react? With which substance does it react? Flammability? Corrosiveness? , etc. Chemical Changes: The changes that occur in the process of producing new substances. Combustion, Matter And oxidation, decomposition, etc. Measurement

Describing Chemical Change Chemical Reaction: the actual phenomenon that occurs when chemicals change in composition. Chemical Equation: a symbolic representation of a chemical reaction. Based on the Atomic Theory. Quiz Question: Write the balanced chemical equations for the reactions of (1) Sodium (Na) + Water (HOH) Matter And (2) Potassium (K) + Water Measurement

Chemical Reactions and Equations + + 2 Na + 2 HOH 2 Na. OH + H 2 2 K + 2 HOH 2 KOH + H 2 (Hint: single displacement or replacement reaction) Matter And Measurement

Matter and the Atomic Theory • • Atoms are the building blocks of all matter. Elements are made of the same kind of atom. Compounds are made of two or more different kinds of atoms. Matter And Mixtures are composed of different elements/compounds Measurement together.

Heterogeneous Classification of Matter * Cu(NO 3)2 Mixtures (Heterogeneous) Physical Homogeneous Mixtures Separation Solutions (Homogeneous) Physical Cu(NO 3)2 (aq) Cu(NO 3)2 (s) Separation Compounds Chemical Decomposition Elements Pure Substances Matter And Measurement

Separatory Techniques • methods of physically separating (purifying) substances from mixtures and solutions into pure substances. • based on differences in physical properties of the substances present in the mixture/solution. 1. Filtration – by solubility vs. insolubility 2. Metal Smelting & Refining - by differences in melting point (ability to form a liquid) 3. Distillation –by differences in boiling points (ability to form a gas) 4. Chromatography – by differences in degree of solubility Matter And Measurement

(1) Filtration: Separates insoluble solid substances from liquids and solutions. Mixture: K 2 Cr 2 O 7(s) +Na. NO 3(s) + H 2 O K 2 Cr 2 O 7(s) Na. NO 3(aq) Matter And Measurement

(2) Metal Smelting & Refining These techniques are used to differentially melt mixtures of metals (alloys) by means of their different melting points (ability to form a liquid when heated). The sweat furnace operates at a temp at which one metal is selectively melted from a component, leaving the metal with the higher melting point, usually a ferrous metal as a recoverable solid. Example: mixture of Cu + Zn, heated to 500°C Matter And Measurement

* (3) Distillation: Separates homogeneous mixture on the basis of differences in boiling points (ability to form a gas). Substance b. pt. Ethyl Alcohol 77 o. C Water 100 o. C Sodium Chloride 1413 o. C Solution: Alcohol + Matter And Measurement

Distillation of Hydrocarbons: Petroleum Refinery Towers compounds composed of molecules arranged in a long chain of carbon atoms with hydrogen atoms attached to the carbon chain. Name (b. pt. C) # C Structural Formula Methane (-162) 1 CH 4 Ethane (-89) 2 CH 3 Propane (-42) 3 CH 3 CH 2 CH 3 Butane (-0. 5) Pentane (36) 4 5 CH 3 CH 2 CH 3 CH 2 CH 2 CH 3 Hexane (69) 6 CH 3 CH 2 CH 2 CH 3 Heptane (98) 7 CH 3 CH 2 CH 2 CH 2 CH 3 Octane (126) 8 CH 3 CH 2 CH 2 CH 2 CH 3 Nonane (151) 9 Decane (174) 10 CH 3 CH 2 CH 2 CH 2 CH 3 CH 2 CH 2 CH 2 Matter CH 2 CH 3 And Measurement CH CH CH 2 2 3

Distillation of Hydrocarbons: Petroleum Refinery Towers 0 C 120 C 200 C 250 C 300 C Matter And Measurement

Separation by differences in ability to form a gas (boiling points) Mixture / Solution or Pure Substance? H 2 O vapor Physical Separation Cu(NO 3)2(s) • Mixtures can be separated by differences in the physical properties of the substances they are composed of. Matter And Measurement • Pure substances cannot be separated by physical methods.

Separation by differential solubility, filtration and evaporation H 2 O vapor Mixture: Cd. S (yellow, insoluble substance), Cu(NO 3)2 (blue soluble substance), H 2 O(clear liquid). Matter And Measurement

(4) Chromatography: Separates substances on the basis of their differences in their solubility in a specific solvent. Filter paper Substance to be separated (black ink) Solvent: 50 Water: Alcohol {Paper Chromatography} Matter And Measurement

Matter And Measurement

Heterogeneous Classification of Matter * Cu(NO 3)2 Mixtures (Heterogeneous) Physical Homogeneous Mixtures Separation Solutions (Homogeneous) Physical Cu(NO 3)2 (aq) Cu(NO 3)2 (s) Separation Compounds Chemical Decomposition Elements Pure Substances Matter And Measurement

Chemical Decomposition of Pure Substances • Cannot be separated by physical means. • Composed of one substance only, which can be either an element or a compound. • Compounds can be broken down by chemical means, elements cannot. Examples of pure substances: Gold (Au), Oxygen (O 2), Water (H 20), Methanol (CH 3 OH), Table salt (Na. Cl) Matter And Measurement Each has its specific physical properties (m. pt. , density, etc. )

Compounds can be broken down into more elemental particles (elements) by chemical decomposition reactions. Electrolysis of Water: 2 H 2 O (l) → elect. 2 H 2 (g) + O 2 (g) Matter And Measurement {Electrolysis}

How do we get pure Sodium? 2 Na. Cl (l) → 2 Na elect (l) + Cl 2 (g) Na. Cl is electrolyzed in a Downs cell. Matter And Measurement

Elements cannot be broken down into more elemental particles by ordinary chemical means. Matter And Measurement

Classification of Matter Heterogeneous Physical Mixture Homogeneous Separation Physical Separation Chemical Element Decomposition Compound Solution Matter And {mixture vs. Measurement compound}

Units of Measurement length (m) mass (g, kg) volume (m. L, L) temperature (o. C, o. K) time (s) Matter And Measurement

Metric System When using dimensional analysis for metric problems: always consider the larger unit as having a value of 1, then the smaller unit would contain a large multiple of that unit. Example: 1 m compared to cm. SI Prefixes Prefix Symbol Meaning Multiplier (numerical) (exponential) yotta Y septillion 1, 000, 000, 000 1024 zetta Z sextillion 1, 000, 000, 000 1021 exa E quintillion 1, 000, 000 1018 peta P quadrillion 1, 000, 000 1015 tera T trillion 1000, 000 1012 giga G billion 1, 000, 000 109 mega M million 1, 000 106 kilo k thousand 1, 000 103 hecto h hundred 100 102 deka da ten 10 101 1 100 UNIT X 1000 X 10 ONE 1 deci d tenth 0. 1 centi c hundredth 0. 01 milli m thousandth 0. 001 micro millionth 0. 000 001 nano billionth 0. 000 001 10 -9 pico trillionth 0. 000 000 001 10 -12 femto quadrillionth 0. 000 000 001 atto quintillionth 0. 000 000 000 001 zepto z ( ) sextillionth 0. 000 000 000 001 yocto y septillionth 0. 000 000 001 10 -1 X 10 10 -2 10 -3 X 1000 10 -6 10 -15 Matter 10 -18 And Measurement 10 -21 10 -24

Atomic Dimensions Atoms Tenth of a nanometer (10 -9 m) Nuclei of atoms Hundredth of a picometer (10 -12 m) Protons & Neutrons Fentometer (10 -15 m) Quarks & electrons Attometer (10 -18 m) Matter And Measurement

Metric Conversions Always convert PREFIXES to UNITS (not PREFIXES to other PREFIXES) Example: Mm compared to pm. Factors, ratios, equivalences. Example: cm compared to m. SI Prefixes Prefix Symbol Meaning Multiplier (numerical) (exponential) yotta Y septillion 1, 000, 000, 000 1024 zetta Z sextillion 1, 000, 000, 000 1021 exa E quintillion 1, 000, 000 1018 peta P quadrillion 1, 000, 000 1015 tera T trillion 1000, 000 1012 giga G billion 1, 000, 000 109 mega M million 1, 000 106 kilo k thousand 1, 000 103 hecto h hundred 100 102 deka da ten 10 101 UNIT meter, liter, gram ONE 1 100 deci d tenth 0. 1 10 -1 centi c hundredth 0. 01 10 -2 milli m thousandth 0. 001 10 -3 micro millionth 0. 000 001 10 -6 nano billionth 0. 000 001 10 -9 pico trillionth 0. 000 000 001 10 -12 femto quadrillionth 0. 000 000 001 atto quintillionth 0. 000 000 000 001 zepto z ( ) sextillionth 0. 000 000 000 001 yocto y septillionth 0. 000 000 001 10 -15 Matter 10 -18 And Measurement 10 -21 10 -24

Metric Conversion Problems km • How many pm are there in 0. 0023 cm? • Change 60. L E N G T mph. H hm dam 1 mile = 5, 280 ft. METER (m) 1 yd = 36 in. dm 3 ft. = 1 yard to km/s. {Hint: 1 mi. = 1. 6 km} cm 2. 54 cm = 1 in. 12 in. = 1 ft. mm • How many m 3 of water are there in 25 ft 3 ? 3 3 3 Matter And Measurement

Volume: Liter (L) and the milliliter (m. L) 10 cm v A liter is a cube 1 dm 3 = 10 cm long on each side. 1 L = dm 3 = (10 cm)3 = (10 X 10) cm 3 = 1000 m. L or 1 m. L = 1/1000 L Cubic centimeter v A milliliter (m. L) is a cube 1 cm long on each side. = milliliter Matter And Measurement

Temperature: measure of the average kinetic energy * (motion caused by heat) of the particles in a sample. {K. E ∝ Temp} T = change in temp 373 -273 100 K = C + 273. 15 100 -0 100 212 - 32 180 C = ( F − 32) 1. 8 As KE increases molecules vibrate more and their volume expands (Temp). Matter And Measurement F = 1. 8( C) + 32

asured vs Exact Numbers • Measured Numbers: (1) Accuracy & Precision (2) Uncertainty (3) Significant figures & rounding-off • Exact Numbers: from formulas, definitions & counting For sphere 1 mile = 5, 280 ft 1 km = 1, 000 m Matter And Measurement

Measured Numbers: Accuracy versus Precision • Accuracy refers to the proximity of a measurement to the true value of a quantity. • Precision refers to the proximity of several measurements to each other. Matter And Measurement

Measured vs. Exact Numbers Measured numbers are obtained when a measuring instrument (ruler, balance, thermometer) is used to determine a physical property of a substance. The number of significant figures these measurements contain depend on the accuracy of the instrument being used. uncertainty 13. 7 +0. 1 7. 63 +0. 01 Matter And Measurement uncertainty

Uncertainty in Measurements Different instruments have different degrees of accuracy, uncertainty is + 1 of estimated digit. +0. 1 +0. 01 uncertainty 89. 5 m. L 2. 65 m. L Matter And Measurement

Measured vs. Exact Numbers METRIC-ENGLISH CONVERSIONS ENGLISH Exact Numbers km L E N G T H hm dam METER (m) dm cm 1 mile = 5, 280 ft. Measured Numbers (1 in is exact, the 2. 54 cm is measured) 2. 54 cm = 1 in. 1 yd = 36 in. 3 ft. = 1 yard 12 in. = 1 ft. mm How many km are there in a Marathon (26 miles)? Matter And Measurement

Significant Figures • Significant figures refers to digits that were accurately measured by an instrument. Example: 220 g, 220. 5 g, 220. 507 g. (all numbers above are measures of the same object, what is the difference? ) accuracy Matter And Measurement

Rules for determining the number of Significant Figures 1. All nonzero digits (NZD) are always significant. 2. Zeroes between NZD are always significant. Ex: 103 3. Zeroes to the left of NZD are never significant. Ex: 0. 0103 4. Zeroes to the right of NZD are significant if a decimal point is written anywhere in the number. Ex. 0. 01030 Matter And Measurement

Rounding-off • Round-off your calculated numbers, to the correct number of significant figures, so we do not overstate the accuracy of our answers. Example: 23 g + 23. 632 g = 46. 632 = 47 g You cannot add an inaccurate measurement to a accurate measurement and get and accurate answer. Matter And Measurement

Significant Figures in Addition & Subtraction * • When addition or subtraction is performed, answers are rounded to the least significant decimal place. Example: add the following numbers 34 231. 678 0. 00354 265. 68154 266 Matter And Measurement

Significant Figures in Multiplication & Division * • 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. (29. 2 – 20. 0) = 9. 2 Example: (29. 2 – 20. 0) (1. 79 x 105) 1. 39 Calculator answer = 1. 1847482 x Correct answer = 1. 2 x 106 Matter And Measurement

Uncertainty in Measurements • Piece of Black Paper – with rulers beside the edges: Determine the Area of Black Paper! Let’s look more accurately ! Area = Length x Width Matter And Measurement

Uncertainty in Measurements • Piece of Paper – Side A enlarged – How long is the paper to the best of your ability to measure it? 13. 6 cm + 0. 1 cm When using an instrument your last digit recorded should be a significant digit estimated between the two smallest Matter Andbe measurement lines of your instrument. Your precision would Measurement + 1 of that digit.

Uncertainty in Measurements • Piece of Paper Side B – enlarged – How wide is the paper to the best of your ability to measure it? 7. 63 cm + 0. 01 cm When using an instrument your last digit recorded should be a significant digit estimated between the two smallest Matter Andbe measurement lines of your instrument. Your precision would Measurement + 1 of that digit.

Area of Paper Area = 13. 6 cm x 7. 63 cm = 103. 768 cm 2 is the calculator answer. 104 cm 2 Matter And Measurement

Density: A Physical property of a substance, defined as: • Amount of matter (# atoms) per unit volume = compactness. • the mass divided by the volume. D= m V = Mass (g) Volume (m. L) Matter And Measurement

Density and Temperature Density: the mass of a substance divided by its volume. Temperature: a measure of the amount of kinetic energy (motion) an object possesses. As the temperature increases the volume increases due to the greater kinetic energy of the atoms or molecules. The mass is not affected. Matter And Measurement

Density of water at various temperatures °C 0. 0 4. 0 15. 0 °F 32. 0 39. 2 59. 0 D in g/cm³ 0. 9998425 1. 0000000 0. 9991026 20. 0 25. 0 37. 0 50. 0 100. 0 68. 0 77. 0 98. 6 122. 0 212. 0 0. 9982071 0. 9970479 0. 9933316 0. 9880400 0. 9583665 Matter And Measurement

* Density Problems For a Fe metal object whose density is 7. 86 g/m. L. (a) What is the mass (g) of a piece of this metal if it displaces 12. m. L of water in a graduated cylinder? (b) What is the volume in m. L of 34 kg of this same metal? Matter And Measurement

* Density Problems The density of Hg is 11. 7 g/m. L. What is it in kg/m 3? 3 Matter And Measurement

Density of various substances Density is directly proportional to the Molecular Weight of a substance. {DBr MW} Matter And Measurement