Measurements and EnergyExam 1 Concepts You Should Know:Exam 1 Concepts You Should Know:Scientific MeasurementScientific MeasurementUnit ConversionsUnit Conversions (Exam Format)Uncertainties in Scientific MeasurementEnergy and ThermodynamicsUnits of EnergyFirst Law of ThermodynamicsExothermic and EndothermicState FunctionsInternal Energy (E)Another Useful State FunctionWhat You Should KnowCH110 FA10 SAS 1By the end of Today’s Lecture you should know:SI units and metric conversionsAccuracy and precisionInternal energy and the First Law of ThermodynamicsState FunctionsKEY QUESTIONS: THE BIG PICTUREMeasurements and EnergyHow can I use dimensional analysis to make chemistry problems easier?How can chemical thermodynamics help me to understand energy?Remember: Energy is stored in molecules. How can we use it?What are the standard units of measure in chemistry?What forces drive chemical reactions and how can a chemist harness them?Ballot for use in class.Exam 1 Concepts You Should Know:CH110 FA10 SAS 2• What do the numbers on the periodic table mean?• How do we name common ions, acids, etc.?Chapter 2: NomenclatureChapter 3: Chemical FormulasChapter 6: Energy, Atoms, Orbitals, and the Origins of the Periodic Table• What is mass percent?• What is a mole? What is molecular weight?• What are the empirical formula and the molecular formula of a compound?• What is the relationship between photons, their wavelength, their frequency, and their energy?• How does all that stuff about photons help chemists to understand the nature of atoms?• What is an orbital? How is it defined?• What is the electron configuration of an atom? How do I represent it?• How do the shape, size, and number of orbitalshelp me to understand the periodic table?Exam 1 Concepts You Should Know:CH110 FA10 SAS 3Chapter 7: Periodic TrendsChapter 8: Bonding and Lewis Structures• What are ionization energy, electron affinity, and electronegativity?• What are the trends in atomic size?• How are the sizes of atoms and ions related?• How do these show up in the periodic table?• What are the three types of bonding?• How do we describe bonding in ionic solids?• How is covalent bonding described in terms of enthalpy, strength, bond order, etc.?• What is a Lewis structure?• What do we learn about a molecule when we see that it has more than one Lewis structure?• How do you use the octet rule and its violations to help predict Lewis structures?Scientific MeasurementCH110 FA10 SAS 41. Metric Measurement: SI Unitsmass:length:time:temperature:energy:2. Important prefixes you must knowmega (M):kilo (k):centi (c):milli (m):micro (μ):nano (n):Scientific MeasurementCH110 FA10 SAS 53. Significant FiguresHow many significant figures are there in each of these numbers?Which has the most?Is it even unambiguous?4. Uncertainties• How sure am I that two numbers are actually different?• If my calculator reports a decimal to eight digits, should I use them all in my answer?854 ⇒0.00854 ⇒85400 ⇒Unit ConversionsCH110 FA10 SAS 6Dimensional analysis and careful unit conversion are critical to success.Ex. 1: A laser emits 488 nm light. What is this wavelength in meters? In centimeters?Unit Conversions (Exam Format)CH110 FA10 SAS 7An unknown liquid has a density of 2.14 g/mL. How many mL would a 6.42 g sample of this liquid occupy?A) 3.00x10-3mLB) 2.14 mLC) 3.00 mLD) 6.42 mLE) 2.14x103mLUncertainties inScientific MeasurementCH110 FA10 SAS 8• Scientists learn about the world around us through _____________________ .• How certain can we be that a given measurement yields the correct answer?Precision : Accuracy :Measurements are not perfectEnergy and ThermodynamicsCH110 FA10 SAS 9kinetic energy potential energymechanical 1/2mv2 mass in a place where force can actelectrical moving charge Q1Q2/d(electrostatic)light photonschemical bondssound molecules moving uniformlynuclear binding energyheat molecules moving randomlygravitational mghwhere g = 9.8 m/s2Thermodynamics : Thermochemistry:Units of EnergyCH110 FA10 SAS 10• SI unit: Joule (J)[KE of a 2 kg object moving at 1 m per second using 1/2 mv2, or PE of 100 g at height = 1 m using mgh]In chemistry (!!!)kilojoule 1 kJ = calorie 1 cal = Calorie (dietary) 1 Cal =First Law of ThermodynamicsCH110 FA10 SAS 11“Law of conservation of energy”• Energy can be _________ from one form to another, but the total energy ___________________• all energy lost by a _______ under observation must be gained by the ___________ (and vice versa)*during energyconversion, some heat is alwaysproducedExothermic and EndothermicCH110 FA10 SAS 12ExothermicenergySystem → Surroundings ∆E = EndothermicenergySurroundings → System ∆E =State FunctionsCH110 FA10 SAS 13State Function: ∆ elevationAB• Δelevation _____ a state function – its value _______ depend on past history!• Distance traveled _____ a state function• Time to bottom _____ a state functionInternal Energy (E)CH110 FA10 SAS 14Quantitative definition:The capacity to _______ or ___________E is a state function… Internal Energy (E) : ∆E = Efinal– Einitial∆E = +Another Useful State FunctionCH110 FA10 SAS 15Enthalpy (∆H)∆H = qpDefined as Energy transferred when P is constant(think of our lake example with dams blocking the streams)Chemical reactions are commonly run at constant pressure (atmospheric pressure); we will frequently refer to energy and enthalpy interchangeably.What You Should Know CH110 FA10 SAS 16Units and Basic Dimensional Algebra• How do I manipulate exponents?• How do I perform metric conversions?•What are significant figures?Energy and State Functions• What is the First Law of Thermodynamics?• What is meant by “system” and “surroundings”?• What is the difference between an endothermic or exothermic process?• What is a State Function?• What is the meaning of Internal Energy and what is it composed of?• What is the meaning of