Week 2 Ch 2 Lab 3. Metric Measurements

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South Texas College *

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Chemistry

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Dec 6, 2023

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Note: All your answers to questions must be in Red or other color (not including blue) for easier grading. Points will be deducted if you do not distinguish your answers. Lab 3. Metric Measurements Objectives:  Convert between metric units for mass, volume and size.  Use a gram balance to obtain the mass of an object.  Make accurate and precise measurements with a graduated cylinder and serological pipette.  Convert temperature between the two temperature scales. Vocabulary:  Metric  SI  Meters  Liter  Meniscus  Gram Introduction: The metric system uses standardized units of measurement for length, mass, and volume, ensuring measurements are reproducible and easily made. Appropriate instruments are used to make these measurements. For example, balances measure mass in grams and graduated cylinders measure volume in milliliters. Measurements in science use metric units. The metric system was developed in France in 1791 so that scientists had a common unit for research comparisons. In 1960 the metric system became the basis for the International System of Units ( SI units). The basic units of these measurements for the metric system are listed in the chart below. Base Units of Measure  Length: meter (m)  Mass: gram (g)  Volume: liter (L)  Time: seconds (s)  Temperature: Celsius (C)

Metric Prefixes Prefix Unit Multiplier Scientific Notation Kilo- k 1,000 10 3 Hecto- h 100 10 2 Deca- da 10 10 1 One base (m, L, g) 1 10 Deci- d 0.1 = 1/10 1/10 10 -1 Centi- c 0.01 = 1/100 1/100 10 -2 Milli- m 0.001 = 1/1,000 1/1,000 10 -3 Micro- µ 0.000001= 1/1,000,000 1/1,000,000 10 -6 Converting Metric Units When you are converting a smaller unit to a larger unit, you move the decimal point to the left the appropriate number of steps. Keep in mind each time you move the decimal point you are dividing by 10. When you are converting from a larger unit to a smaller, you will move the decimal point to the right. This means each time you move the decimal point you are multiplying by 10. Watch the following video to learn about the common metric units: https://youtu.be/XzhKc6jD0ws Metric Conversion Practice 1. 1 meter = 100 cm 2. 56.2 millimeters = 0.0562 m 3. 13 kilometers = 13,000 m 4. 16 ml = 16000.00 µl 5. 9 µl = 0.000009 L 6. 32 mm = 32,000,000 nm 7. 28 m = 0.028 km Part 1: Length and Area Length is measured with a metric ruler, a meter stick, or a measuring tape. The basic unit of length is meters . Examine intervals marked on the metric rulers. You should see centimeter and millimeter divisions. Use a ruler to make the following measurements making sure to include units. (Watch the Lab 3: Metric Measurements video) 8. Length of the book 30 cm . 9. Width of the book 22.6 cm .

10. Area of the book 678 cm 2 . (Area = length × width) 11. Diameter of a penny 2 cm . 12. Measurement of bone 30.5 cm . Part 2: Volume Volume is the space occupied by an object. Units of volume are cubed (i.e. three dimensional) units of length. The liter (L) is the basic metric unit of volume. There is several instruments that can be used to measure volume. The most common way of measuring volume will be with graduated cylinders and pipets.  Watch the following video to learn how to use graduated cylinders: https://youtu.be/eUIcebi1GVc  Measure and pour 50 mL of water into a 100 mL graduated cylinder. Notice how the water is curved. This is called the meniscus and is due to surface tension and adhesion of water molecules to the sides of the cylinder. When measuring liquids in a cylinder always get eye level with the meniscus and read the volume at the lowest level of the curve. Besides graduated cylinders we can also measure volumes using a serological pipet . The following video shows how to use these types of pipets. At South Texas College we will be using the syringe style pump, however in research electronic pumps are more commonly used. When using this type of pipets, it is important to note the amount that each pipet can hold and to note the numbers printed on it to ensure you are correctly measuring the desired volume. Watch the following video to learn how to use a serological pipet: https://youtu.be/in82VTLWI_w We can also measure the volume of a solid object by a method called water displacement. (Watch the Lab 3: Metric Measurements video)  Obtain a 50-mL graduated cylinder, a rock, and a glass marble.  Fill the graduated cylinder with 25 mL of water. Record this initial volume in your table. Gently drop the rock. This is going to raise the meniscus. Record that new volume and calculate the final volume of the rock (New Volume – Initial Volume = Final Volume).  Repeat the steps with the glass marble. Initial Volume New Volume (after you add the object) Final Object volume

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13. Roc k 25 ml 27 ml 2 ml 14. Mar ble 25 ml 27 ml 2 ml Part 3: Mass The gram is the basic metric unit of mass. Use the electronic balance to measure the following items. Make sure that first you tare (set to zero) the balance. If you have a weigh boat, you must tare the balance with the weigh boat in place. Watch the following video to learn how to use an electronic balance: https://youtu.be/0UymyTJATLc Take the mass of the following objects. (Watch the Lab 3: Metric Measurements video) 15. Rock 6.9 g 16. (2) Pennies 4.9 g 17. (5) Paperclips 4.7 g 18. Convert your paperclips mass to mg 4,700 mg Part 4: Temperature The basic unit of temperature in the metric system is the degree Celsius. (°C). There are no commonly derived units. To get a feel for degrees Celsius, consider the following temperatures:  Ice water and the freezing point of water are 0°C  Room temperature water is 20 – 25°C • Normal body temperature is 37°C  Water gets too painful to touch between 50 – 60°C  Water boils at 100°C Watch the following video on to learn how to use a thermometer: https://youtu.be/TU_AxETS2V0 Temperature conversion: Use the following information to convert the temperatures. °C to °F: Multiply by 9, then divide by 5, then add 32 °F to °C: Deduct 32, then multiply by 5, then divide by 9 19. 28 °C = 82.4 °F 20. 80 °C = 176 °F 21. 62 °F = 16.6667 °C 22. 3 °F = -16.1111 °C

Measure the following temperatures with the thermometers. Remember the that in science we always use the metric system and therefore your temperatures should be in °C. (Watch the Lab 3: Metric Measurements video) 23. Room temperature water 21°C 24. Hot water 48°C 25. Ice water 6°C LICENSES AND ATTRIBUTIONS  " Metric System Conversions " by Lumen Learning , LibreTexts is licensed under CC BY 4.0 .  " Metrics and Measurements " by Orange County Biotechnology Education Collaborative , LibreTexts is licensed under CC BY-NC 4.0 .