Part B: Volume MeasurementsQuestion:1. Which type of glassware – the 10 mL pipette, the 100-mL graduated cylinder, or beaker- has the least amount of uncertainty? Explain.2. What is the uncertainty of the volume measurement performed with the 10 mL pipette?3. What is the uncertainty of the volume measurement performed with the 100 mL graduated cylinder?Part C: Mass MeasurementsQuestions:CH100: Fundamentals for Chemistry page: 1 of 5PCC-CascadeExperiment: INTRODUCTION TO THE CHEMICAL LABORATORYPURPOSE: - To become familiar with basic lab safety principles.- To become acquainted with metric measurements, the use of common lab apparatus, and the basic parts of the lab write-up.INTRODUCTION: The chemistry lab is not a safe environment. The appreciation of what constitutes safe laboratory practices is paramount for any student working in the chemistry lab. Safety practices serve not only to protect you from harm but your fellow colleagues as well. Moreover, conscientious lab protocol will also serve to minimize problems associated with chemical cross contamination, which can ruin the results of an otherwise successful experiment.In the lab, the primary goal is to make proper observations of chemical and physical properties and processes. In addition to qualitative observations, scientific measurements represent a vital component of your observation repertoire. Scientific measurements will be made using the metric system, including measurements of the quantities of mass (in grams), volume (in L or mL) and length (m or cm). These quantities along with temperature representthe basic measurement building blocks of quantitative observation and can be combined to establish more elaborate quantities of measure, such as density (grams/mL).How well a measurement is taken determines both its precision and its accuracy. Precision isrelated to the reproducibility to the measurement. It is a comparison of several measured values obtained in the same way. For example, a student measures the volume of a liquid three times, obtaining in the same way. For example, a student measures the volume of a liquid three times, obtaining the values 3.66 mL, 3.62mL, and 3.64mL. These measurements have high precision; there is only a 0.040 mL difference between the highest and lowest values.Accuracy is a comparison of a measured value to the accepted, or true, value. Suppose the volume of the liquid had actually been 5.44 mL. Then the accuracy of the three measurements taken would be low because a difference of 1.80 mL between the average measured value and the true value is relatively large.A good scientist is always trying to achieve both high precision and high accuracy in the laboratory.Measuring Length:All measurements are estimated values. They are obtained by using a measuring device thatis marked with a calibrated scale. The scale contains marks and printed numeric values at regular intervals. There is a degree of uncertainty in all measured values. The degree of uncertainty is indicated by the number of significant figures given in a measurement (See textbook). For example, of the two rulers shown in figure 1, is one more uncertain than the other?CH100: Fundamentals for Chemistry page: 2 of 5PCC-CascadeFigure 1In the top ruler, each graduation represents 1 cm. It is certain that the right end of the copperrod lies between the 12th and 13th graduations. By estimating only one digit, the reading can be taken as 12.5 cm. In the bottom ruler, the larger graduations again represent 1 cm, and again the end of the rod lies between the 12th and 13th graduations. This ruler also has smaller graduations, however, representing 0.1 cm, and the rod lies between the 5th and 6th smaller graduations. By estimating only one digit, the reading can be taken as 12.55 cm.Measuring volume:When taking volume measurements, you will notice that the surface of the liquid is curved. This curved surface is called a meniscus. You should always take our reading from eye level and report the position of the bottom of the meniscus (See figure 2)Figure 2Once you measure a volume (or any other physical quantity) experimentally, you should consider the precision of your measurements. To quantify the uncertainty of a measurement we shall use a calculation called percent range to express precision. Percent range can be calculated for an individual measurement or a set of measurements. For an individual measurement:%100 valuemeasured increment emeasureablsmallest Range % CH100: Fundamentals for Chemistry page: 3 of 5PCC-CascadeNote: The smallest measurable increment is smallest discernible value you can make with a particular measurement device.For a set of measurements:%100 valuealexperiment average uelowest val - luehighest vaRange % When you have more than one data point, the precision of the measurements is related to thespan, or range, of the values (i.e. highest value minus lowest value) and the average of the values.Part A: LAB SAFETYA. Review the lab safety videoB. Identify the locations of the following safety items in the labs:1. First Aid Kit:2. Safety shower:3. Eye Wash Fountain:4. Fire Extinguisher:5. Fire Blanket:6. Fume Hoods:7. Emergency Phone8. Fire Alarm (s):CH100: Fundamentals for Chemistry page: 4 of 5PCC-CascadePart B: Volume Measurements1. Measure out approximately 8.10 mL of water using a 10 mL pipette and pump.2. Read the water volume from the marks on the cylinder and record your reading on the report sheet, using the correct number of significant figures.Volume of water in 10 mL pipette =_________mL3. Carefully dispense this water into a 100 mL graduated cylinder.4. Read the water volume from the marks on the cylinder and record your reading on the report sheet, using the correct number of significant figures.Volume of water in 100 mL graduated cylinder =_________mL5. Carefully pour all the water into a 50 mL beaker. Be sure the beaker has measurements6. Read and record the water volume, using the correct number of significant figures.Volume of water in 50 mL beaker =_________mLQuestion: 1. Which type of glassware – the 10 mL pipette, the 100-mL graduated cylinder, or beaker- has the least amount of uncertainty? Explain.2. What is the uncertainty of the volume measurement performed with the 10 mL pipette?3. What is the uncertainty of the volume measurement performed with the 100 mL graduated cylinder?CH100: Fundamentals
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