CHEM 121 1st Edition Lecture 4Outline of Last Lecture I. AtomsII. ElectronsIII. ElementsIV. IsotopesV. Atomic MassesOutline of Current Lecture I. MeasurementII. Units of MeasurementsIII. DensityIV. EnergyV. Law of Conservation of EnergyVI. Solving Chemical Problems (Unit Analysis/ Dimensional Analysis)Current LectureMeasurementMeasurement- quantitative observation- Precision: how close the measurements are to each other- Accuracy: how close the measurements are to the real/true value- Uncertainty: estimating when taking a reading in a measurement- More digits= better certainty= better precisionUnits of Measurements-Unit: A standard quantity used in measurements; can be added, subtracted, multiplied, and divided (essential for any experimental science)These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.- Common SI Base UnitsDimension Unit Name Unit AbbreviationMass Kilogram kgLength Meter mTime Second sTemperature Kelvin KAmount of Substance Mole (6.022x1023) mol- Derived Units:- Force- Newton (N: (kgm)/ s2)-Mass in gravitational field- weight (gravitational force)- Same mass, different gravitational field and weight- Volume- Cubic Meter (m2)-Other common units: L, mL, cm3 **memorize 1 mL= 1 cm3- Pressure- pascal (Pa: kg/ (ms2))-Other common units: atm, torr,kPa- Energy- joule (J: (kgm2)/s2)-Other common units: cal, Cal, kJ- Electrical charge-coulomb (C)-Other common units: mC-English Units** Memorize 1 inch = 2.54 cm-Prefix Multipliers- Purpose is to express very large or small quantities in a compact way- Change the values of the unit by powers of 10- Wide range in units- Density-Density: mass per unit volume- Density (d) = mass (m) ÷volume (V)-Manipulations of Equation : m=dxv ; v=m÷V-Basic unit: kg/m3- Other common units: g/cm3, g/mL-Important to Pure Substance-Intensive property- Intensive property: independent of the size or amount of the substance-Examples: density, molar mass, heat capacity- Extensive property: dependent on the size or amount of the substanceEnergy- Energy: capacity to do work- Unit: Joule (J)- Work: the action of a force through a distance-Work& Heat: two major forms of energy transfer used to convert one type of energy to another- Forms of energies- Potential energy: stored energy- Kinetic energy (KE): energy in motion- Electrical energy: energy from the movement of charged particleso The farther charged particles are apart, the greater the energy- Chemical energy: energy stored in chemicals (compounds) via chemical bondso A form of potential energyo Examples: electric energy (electrochemistry), heat (thermochemistry)Law of Conservation of Energy: Energy is neither created nor destroyed, but it can change from one form to another. – James Prescott JoulesSolving Chemical Problems (Unit Analysis/ Dimensional Analysis)- Unit analysis is the process of converting from one unit or entity to another.- Every measurement needs a unit, entity sometimes- Use units/ entity as a guide to solve the problem- Use a solution map: A visual outline that shows the route you took to solve the problem (Example: If you were asked to give how many seconds there are in a year. To show how you got your answer you would write down the following process: YearDayHourMinuteSecond. This process shows the steps that one would take to answer the question given.- Choices of units/entities in a solution mapo Every arrow corresponds with a conversion factor- Conversion Factorso Two different units/entities bridged with a numerical relationo Equation statements would be like 1 day= 24 hourso Ratio statements would be like 24 hours ÷ 1 day- Powering conversion factorso Commonly used in conversion of units involving area or volume when powering aconversion factor, power units and