CHE 026L LAS 1- Units of Measurement.pdf

Course Code: CHE 026L Laboratory Activity Sheet #1 Name:____________________________________________________________...

Course Code: CHE 026L Laboratory Activity Sheet #1 Name:____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ ACTIVITY NO. 1 UNITS OF MEASUREMENT & ITS CONVERSION, SIGNIFICANT FIGURES AND PERCENTAGE YIELD Objectives:  Memorize the major units of measurement in English and metric systems, and be able to convert from one system to another  Identify the number of significant figures in a reported data.  Calculate percentage yield in experimental scenarios. Materials:  Calculator, Scratch papers Introduction: Measurements are made on a routine basis. Measurement is the determination of the dimensions, capacity, quantity, or extent of something. In chemical laboratories, the most common types of measurements are those of mass, volume, length, time, temperature, pressure, and concentration. The two systems used for specifying units of measure are the English and metric systems. Units in the English system are historical units of measurement used in medieval England which evolved from the Anglo- Saxon and Roman systems. The metric system is a decimalized system of measurement developed in France in late 18th century. Since the metric system is almost universally used, it is often referred to as the International System of Units and abbreviated SI. The metric system is superior to the English system. Its superiority stems from the interrelationships between units of the same type (volume, length, etc.). Metric unit interrelationships are less complicated than English unit interrelationships because the metric system is a decimal unit system. Procedure: A. The Internal System of Units 1. The SI system is based on seven base units. SI base units are a choice of seven well-defined units by which convention are regarded as dimensionally independent: the meter, the kilogram, the second, the ampere, the kelvin, the mole, and the candela. Quantity Unit Symbol Length Meter m Mass Kilogram kg Time Seconds s Electric current Ampere A Temperature Kelvin K Amount if substance Mole mol Luminous intensity Candela cd 2. Memorize the given SI units along with its symbol. This document is the property of PHINMA EDUCATION  Course Code: CHE 026L Laboratory Activity Sheet #1 Name:____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ B. The Metric System 1. In the metric system, there is one base unit for each type of measurement (length, mass, volume, and so on). The names of fractional parts of the base unit and multiples of the base unit are constructed by adding prefixes to the base unit (refer to the table below). These prefixes indicate the size of the unit relative to the base unit. The metric system is the preferred system of scientific units for several reasons: (1) The majority of countries in the world employ the metric system of measurement (2) the prefixes attached to metric units carry the same meaning for all base units (3) the metric system is based upon powers of ten, which is convenient. The meter (m) is the base unit of length in the metric system. The gram (g) is the base unit of mass in the metric system. The terms mass and weight are often used interchangeably in measurement discussions; technically, however, they have different meanings. Mass is a measure of the total quantity of matter in an object. Weight is a measure of the force exerted on an object by gravitational forces. The liter (L) is the base unit of volume in the metric system. The abbreviation for liter is a capital L rather than a lowercase l because a lowercase l is easily confused with the number 1. Prefix Symbol Meaning Length Mass Volume Mega- M 1,000,000 Megameter Megagram Megaliter (million) Kilo- k 1000 kilometer kilogram kiloliter (thousand) Hecto- h 100 (hundred) hectometer hectogram hectoliter Deka D 10 (ten) Dekameter Dekagram Dekaliter *base unit -- 1 (ones) meter gram liter Deci- d 0.1 (tenths) decimeter decigram deciliter Centi- c 0.01 centimeter centigram centiliter (hundredths) Milli- m 0.001 millimeter milligram milliliter (thousandths) Micro- mc/ μ 0.000001 micrometer microgram microliter (millionths) Nano- n 0.000000001 nanometer nanogram nanoliter (bilionths) As reflected in the table above, it is assumed that kilo means thousand. Hence, a kilometer is equivalent to 1000 meters. Also, when we define milli as thousandths (0.001), this means that a milligram is equivalent to 0.001 gram. Another example is centiliter. Centi means hundredths (0.01). Thus, a centiliter is equivalent to 0.01 liter. Take note that this equivalents are useful in converting one This document is the property of PHINMA EDUCATION  Course Code: CHE 026L Laboratory Activity Sheet #1 Name:____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ unit to other units via dimensional analysis. 2. Memorize the equivalents of the units. Formulate techniques to familiarize the equivalents easily. 3. Convert one metric unit to another metric unit using dimensional analysis and short cut method. Dimensional analysis This would require correct equivalents of metric units. For example when you try to convert 0.0254 L into mL, you must know the correct equivalents of L to ml. Based from the given table, 1 milliliter is equal to 0.001 Liter. Hence, you can write 0.0254 L x 1 mL = 0.0254 mL = 25.4 mL 0.001 L 0.001 Note: The unit that you are looking for should always be the numerator in order to cancel out the unit that you are trying to convert. Short Cut Method/ Ladder Method Converting the same example: 0.0254 L to ______ mL Beginning at the base unit litre (L), we have to take three steps DOWN or we need to move on the RIGHT SIDE of the stairs to reach milliliters (mL). This means that we need to move the decimal in three points to the right of the original number. This document is the property of PHINMA EDUCATION  Course Code: CHE 026L Laboratory Activity Sheet #1 Name:____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ Thus, the answer is 25.4 mL C. English System 1. Memorize the equivalents of each English units LENGTH CAPACITY/ VOLUME 1 inch = 2.54 cm 1 pint = 16 fluid ounces 1 foot = 12 inches 1 quart = 2 pints 1 yard = 3 feet 1 peck = 8 quarts 1 furlong = 220 yards 1 bushel = 4 pecks 1 mile = 8 furlongs 1 pint = 4 gills 1 mile = 5280 feet 1 gallon = 4 quarts 1 mile = 1760 yards 1 pint = 473 mL MASS 1 gallon = 3785 mL 1 kg = 2.2 lbs 1 cubic foot = 1728 cubic inches 1 lb = 454 g 1 cubic yard = 27 cubic feet 1 oz = 437.5 grains 1 fluid ounce = 29. 574 mL 1 lb = 16 ounces 1 tablespoon = 15 mL 1 stone = 14 lbs 1 teaspoon = 5 mL 1 hundredweight = 100 lbs 1 cup = 240 mL 1 ton = 20 hundredweights 1 L = 1.06 qt AREA TEMPERATURE 1 square foot = 144 square inches [°C] = ([°F] - 32) x _5_ 1 square yard = 9 square feet 9 1 acre = 4840 square yards [°F] = [°C] x _9_ + 32 1 square mile = 640 acres 5 1 section = 1 square mile K = [°C] + 273.15 1 township = 36 sections 2. Convert one unit to another unit using dimensional analysis as shown in the example below. a. Convert 2 lbs to ____ grams 2 lbs x 454 grams = 908 grams 1 lb b. Convert 3.5 yards to _____ inches If there is no direct equivalent of the original unit and the desired unit, you can use 2 or more equivalents to arrive to the desired unit. 3.5 yards x 3 feet x 12 inches = 126 inches 1 yd 1 ft This document is the property of PHINMA EDUCATION  Course Code: CHE 026L Laboratory Activity Sheet #1 Name:____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ D. Significant Figures I. A set of guidelines exists for determining the number of significant figures in a measured quantity. These guidelines are: 1. In any measurement, all nonzero digits are significant. 2. Zeros may or may not be significant because zeros can be used in two ways: When zeros are present in a measured number, the following rules are used: a. Leading zeros, those at the beginning of a number, are never significant. 0.0141 has three significant figures. 0.0000000048 has two significant figures. b. Confined zeros, those between nonzero digits, are always significant. 3.063 has four significant figures. 0.001004 has four significant figures. c. Trailing zeros, those at the end of a number, are significant if a decimal point is present in the number. 56.00 has four significant figures. 0.05050 has four significant figures. d. Trailing zeros, those at the end of a number, are not significant if the number lacks an explicitly shown decimal point. 59,000,000 has two significant figures. 6010 has three significant figures. II. Practice identifying the number of significant figures in the given activity sheet. E. Yield Calculation 1. In chemistry, we have theoretical yield, which is the amount of the product calculated from the limiting reactant. The limiting reactant is the reactant in the chemical reaction which limits the amount of product that can be formed. The actual yield is the actual amount produced when the experiment or reaction is carried out. The discrepancy between the theoretical yield and the actual yield can be calculated using the percent yield, which uses this formula: % Yield= __Actual yield__ x 100 Theoretical Yield 2. Compute for the percent yield and unknown values of the given problems in the activity sheet. This document is the property of PHINMA EDUCATION  Course Code: CHE 026L Laboratory Activity Sheet #1 Name:____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ ACTIVITY NO. 1 UNITS OF MEASUREMENT & ITS CONVERSION, SIGNIFICANT FIGURES AND PERCENTAGE YIELD A. The Internal System of Units Fill in the space provided with the correct SI units and symbol for each quantity. Quantity Unit Symbol Length Meter m Mass Kilogram kg Time Second s Electric current Ampere A Temperature Kelvin K Amount of substance Mole mol Luminous intensity Candela cd B. The Metric System Convert the following figures to its desired units. Do not round off your answers. 1. 23 m to ________ km 6. 12 cm to __________ mm 2. 76 L to _________DL 7. 164,000 ml to ______L 3. 93.2 mg to ______Hg 8. 454 g to ___________mg 4. 83.34 dL to ______ L 9. 1,232 kg to _________g 5. 94.1 Dm to _______ m 10. 672 L to ___________kL C. English System Convert the following figures to its desired units. Do not round off your answers. 1. 13 ft to ___________ inches 6. 2.5 gallons to _________ pints 2. 3.5 quarts to _______ pints 7. 39.5oC to ____________ oF 3. 3 pounds to ________ grams 8. 2 square miles to ______ square yards 4. 12 yards to _________ feet 9. 4 tbsp to ____________ fluid ounces 5. 379.55 K to _________oC 10. 3 pecks to _____________ pints D. Significant Figures Determine the number of significant figures in the given numbers. 1. 12,000 ________ 6. 10.002 _________ 2. 2.3403 ________ 7. 34,000 _________ 3. 123.00 ________ 8. 612,000 ________ 4. 0.000344 ______ 9. 0.00230240 _____ 5. 10,234 ________ 10. 210 ___________ This document is the property of PHINMA EDUCATION  Course Code: CHE 026L Laboratory Activity Sheet #1 Name:____________________________________________________________ Class number: _______ Section: ____________ Schedule: _____________________________________ Date: _______________ E. Yield Calculation Calculate the unknown in the given problems. Show your solution. Round off your answers into 2 decimal places. 1. Magnesium carbonate decomposed to form 15 grams of MgO in the actual experiment. If the theoretical yield is 19 grams, what is the percent yield of MgO? 2. If the reaction of the 20 grams Calcium carbonate with an expected theoretical yield of 18 grams Calcium oxide produced a yield percentage of 80%, what is the actual yield of CaO? Questions 1. What is the difference between mass and weight? 2. What is the importance of converting units of measurement in chemistry? Note: A google form version of the activity sheet is available for your convenience. You may opt to answer the activity thru google form instead of typing or taking pictures of your work. However, this may vary among instructors. Please make sure to follow what is recommended by your instructor. This document is the property of PHINMA EDUCATION