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Unit 1 Basic Chemical Math – Guided NotesScientific Method- List the steps to the scientific method Types of Observations and MeasurementsQualitative:Ex:Quantitative: Ex: In chemistry ___________________ are used (International System of Units) — based on the metric systemEx: ___________________________________________________As opposed to U.S customary unitsEx: ___________________________________________________Use the SI units- based on the metric systemLength: __________________________Mass: ___________________________Volume: _________________________Time: ____________________________Temperature: _____________________Why is it important to have a standard of measurement?In every measurement there is a _____________________ followed by a _________________ from a measuring deviceWhich tool(s) would you use to measure:Temperature? _______________________________Volume? ____________________________________Time? ______________________________________Mass? ______________________________________Learning Check: Indicate what is being measured: Length, Mass, or VolumeA bag of tomatoes is 4.6 kg. ________________________A person is 2.0 m tall._____________________________A medication contains 0.50 g Aspirin. ________________31432502470150A bottle contains 1.5 L of water. ____________________Accuracy and PrecisionThree targets with three arrows each to shoot: Can you define accuracy and precision? Accuracy:Precision:Significant Figures and Measurements _________________________________________ (also called __________________________) of a number are digits that carry meaning contributing to the measurements accuracy.More significant figures in a measurement means a more ____________________________ measurement.For example: If someone asks you how much money is in your bank account you might say $50, but your banking app would say $51.37. Which is a more accurate measurement? ______________________________ is a common type of measurement. The measurement is ______________________________________________ and can be expressed without error. Ex: 26 students in a classroom, then there are truly 26 students in a classroom at that given time. Not 25 or 26.5, exactly 26.Exact numbers have ________________________________________ significant figures. They are _________________________________ accurate.Exact numbers: __________________________________ and numbers from _____________________________ relationships (1 foot = 12 inches; 1 L = 1000 mL)In other situations, measurement possesses some degree of error or uncertainty. In other words they are not _____________________________________. Ex: Measurements can only be as accurate as the __________________________ used to measure. In science, measurements should only have ___________________________ degree of uncertainty (or only one estimated digit).Significant Figures come from the ______________________________ digits and the one ________________________________________ digit of a measurement. The number of significant figures will tell us the a____________________________ of the measurement. Reading a Measurement62484021526500Example 1: Measure the blue line:Answer: ____________________________________In you answer, underline the certain digits and circle the uncertain digitHow many sig figs does this measurement have? __________________________________MeasuringThe certain digits come from the ____________________________ on the measuring toolFor example: If the device has markings that represent 1 mL, then the ones place is certain and you would estimate the _____________________________ place (the first decimal)For example: If the device has markings that represent 0.1 cm, then the tenths place is _________________________ and you would estimate the hundredths place (the second decimal)Always measure ______________________ place value past what the device measuresWhat is the measuring tool has markings that represent 100 mL, what place value would you estimate? ____________________________________________________________________________________79819520701000Example 2: What is the length of the red line? Answer: ______________________How many sig figs does this measurement have? __________________________679450228600Example 3: What is the length of the line?Answer: ____________________________________How many sig figs does this measurement have? __________________________________Zero can be an estimated digit and a significant figureExample 4: If you are measuring the temperature of the room and you had the two thermometers below, which would give you a measurement with more accurate measurement and why?24765057785Measurement: _____________________________# of Sig Figs: _______________________________Measurement: _____________________________# of Sig Figs: _______________________________When measuring a liquid, measure volume from the _________________________ of the meniscus ________________________________= the curved upper surface of a liquid in a tube.6248402114550044682696115400Example 5 & 6: How much water is in the graduated cylinders? Measurement: _______________________Measurement: _______________________# of Sig Figs: _________________________# of Sig Figs: _________________________Tools that take measurements digitally include the _________________________ __________________ in the measurementFor example…If a piece of iron is measured on an electron balance and the balance reads 5.68g_____________________ are certain digits and __________ is the estimated digitRules for Determining Significant Figures in a Measurement5 Rules for Significant Figures: All digits _________________________ are significant__________________________ between significant digits are always significant. Ex. 2007 has 4 sig figsTrailing ______________________ in a number are significant ONLY if the number contains a decimal point. Example: 100.0 has 4 sig figs 100 only has 1 sig fig._____________________ in the beginning of a number that only serve as a placeholder are NOT significant. Ex. 0.0025 only has 2 sig figs______________________ following a decimal significant figure are significant. Ex. 0.00470 has 3 sig figs(Use the rules if you would like, but I like the Atlantic-Pacific Method better than the rules!)“Cheat Sheet”/ Atlantic-Pacific Method:Start from the ________________________ side if the decimal is PRESENT.Start from the ________________________ side if the decimal is ABSENT.Go through the number until you hit a whole number, that whole number and everything past it is _______________________________.Whith scientific notation the ______________________ is ignored when counting sig figs. Learning Check:Which answers contain 3 significant figures?0.4760 b. 0.00476 c. 4760 All the zeros are significant in 0.00307 b. 25.300 c. 2.050 x 103 534,675 rounded to 3 significant figures is ________________________In which set(s) do both numbers contain the same number of significant figures? 22.0 and 22.00 400.0 and 40 0.000015 and 150,000State the number of significant figures in each of the following:0.030 m4.050 L1.200 x 10-34 mg5 x 109 kJ 3.00 m 2,080,000 beesCalculations with Sig FigsA calculated answer cannot be more _____________________ than the measuring tool. A calculated answer must match the _______________________ accurate measurement.When rounding, if the digit used to round is 5 or above round upExample: 8.450090983 rounded to 2 sig figs would be ___________________________________Adding and Subtracting:Rule: 203454010795 25.2+ 1.34020000 25.2+ 1.34Example: Learning Check: In each calculation, round the answer to the correct number of significant figures.235.05 + 19.6 + 2.1 = 58.925 - 18.2=Multiplying and Dividing:Rule:Example: 15.7 x 0.63 = Learning Check:2.19 X 4.2 = 4.311 ÷ 0.07 = 2.54 X 0.0028 = X 0.060 Scientific Notation What is Scientific Notation?What numbers are best for scientific notation?Scientific Notation consists of two parts: When you divide by a number that is in scientific notation, use __________________________ around the denominator.Standard Form to Scientific NotationPlace the decimal point so that there is one non-zero digit to the left of the decimal point.Count the number of decimal places the decimal point has “moved” from the original number. This will be the exponent on the 10.If the original number was less than 1, then the exponent is negative. If the original number was greater than 1, then the exponent is positive.Examples:289,800,000 = _______________________________0.000567 = _________________________________Scientific Notation to Standard FormSimply move the decimal point to the right for positive exponent 10. Move the decimal point to the left for negative exponent 10. (Use zeros to fill in places.)Examples:5.093 x 106 = ______________________________1.976 x 10-4 = ______________________________Learning Check: Express these numbers in Scientific Notation:405789 = ______________________________0.003872 = ______________________________3000000000 = ______________________________2 = ______________________________0.478260 = ______________________________Perform the following calculations and report the answer in scientific notation. Consider sig figs. 2.898 x 108 x 5.67 x 10-4 = _____________________________2.898 x 108 / 5.67 x 10-4 = _____________________________Metric Units3819525000The base units for the metric system are ______________________________________________________________________________________________________________________________ are used with these base units to represent a factor of the base unitExample: 1 m= _________________ kmBecause all of these numbers all equal 1 base unit, they also equal each otherExample: 10-2 hg = ___________ mgYou need to know the prefixes from Mega to Micro!Learning check: Select the unit you would use to measure the following:Your height: a) millimeters b) meters c) kilometersYour mass: a) milligramsb) grams c) kilogramsThe distance between two cities: a) millimeters b) meters c) kilometersThe width of an artery: a) millimeters b) meters c) kilometersDimensional Analysis_________________________________________________ is a method used to convert a quantity in one unit into a different unitConversion Factor: Fractions in which the numerator and denominator are ____________________________ quantities expressed in different units. Conversion factors ALWAYS equal ______________ (anything divided by itself is ___________). How many sig figs do conversion factors always have? __________________________________Example: What is the conversion factor involving inches and centimeters?Learning Check: Write conversion factors that relate each of the following pairs of units:Liters and mLHours and minutesMeters and kilometersExample: How many minutes are in 2.5 hours?What conversion factor are you going to use? What units go in the numerator and denominator and why?Steps to Problem Solving:Write down the given amount. Don’t forget the units!Multiply by a conversion factor in the form of a fraction. Remember to cancel a unit, it must be on the opposite side of the fraction.If you do not know a direct conversion factor (like how many seconds are in a year), use multiple conversion factors (like seconds to minutes, minutes to days, and days to years).Multiply numbers in the numerator and divide by the numbers in the denominator.Write your answer with a unit and in proper sig figs. Remember conversion factors have infinity sig figs. Examples: You have $7.25 in your pocket in quarters. How many quarters do you have?5409477-23615500If Jacob runs 2.50 miles, how many meters did he run? 1000 m = ____________________mm0.001 g = ____________________ kg 0.1 L = ____________________ cL 0.01 m = ____________________ dmA rattlesnake is 2.44 yards long. How long is the snake in meters? (note: 1 yard = 0.9144 meters)How many seconds are in 1.4 days?What is wrong with the following setup?An adult human body has 4.65 L of blood. How many gallons of blood is that?Units made up of multiple units:If you have a unit comprised of multiple units, such as miles per hour or cubic centimeters, be sure to include all ___________________________ in your dimensional analysisYou will need to _____________________________ each unit individually_____________________________ is another way of saying divided byThe number attached to the unit is always in the numerator and the denominator is always 1Example: If a car is going 15.0 feet per second, what speed is this in miles per hour?Example: The volume of an object is 4.37 cubic meters, what is the volume of the object in liters?-31750285750TemperatureNotice that 1 _______________ = 1 ________________Which unit of temperature are we going to use most often in this class? _____________________________ScaleMicroscopic/Subatomic- Macroscopic- Symbolic- Some models or pictures represent more than one scale at a time… can you think of an example of this?Draw a picture of ice water on each of the scales below:SubatomicMacroscopicSymbolic276225011684000 ................
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