Introduction to lab techniques post lab

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Florida International University *

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1045L

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Chemistry

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Jun 3, 2024

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Name: Guillermo Rumbos Panther ID: 626887 Course and section number: CHM 1045L U01 TA Name: Giselle Castano Date: 05 /20/ 2024 Introduction to lab techniques post lab Purpose The purpose of this experiment was to familiarize with the equipment used during the semester. Beakers, graduated cylinder, volumetric pipettes, and burets were introduced and the concepts of reading volumes, proper filling technique and the amount of correct significant figures to record for accurate calculations were explained and realized. Introduction In the laboratory chemicals need to be poured, mix, heated, and measured. These actions require proper equipment that must be known how to properly handle and effectively utilized. The basic instruments used in a lab are the beaker, the burette, the volumetric pipette, and the graduated cylinder; each of these has an specific function and accuracy that might be used depending on what is being done in the lab. The beaker is defined by Merriam-Webster as “ a deep widemouthed thin-walled vessel usually with a lip for pouring that is used especially in science laboratories”. The beaker its mostly used for rough measurements as it is not suited for accuracy. For more precise measurements and titration, the burette is implemented. Britannica describes the burette as an “ apparatus used in quantitative chemical analysis to measure the volume of a liquid or a gas . It consists of a graduated glass tube with a stopcock (turning plug, or spigot) at one end. On a liquid burette, the stopcock is at the bottom, and the precise volume of the liquid dispensed can be determined by reading the graduations marked on the glass tube at the liquid level before and after dispensing it”. The burette is usually used for titration, that is a process to determine the concentration of a dissolved substance. The

volumetric pipette is defined by Merriam-Webster as a “s mall piece of apparatus which typically consists of a narrow tube into which fluid is drawn by suction (as for dispensing or measurement) and retained by closing the upper end”. The volumetric pipette is used for precise measurements of liquids and allows them to be poured precisely in the desired container. The graduated cylinder it’s a versatile instrument; it consists of a tall and narrow container that allow to precisely measure liquids up to the nearest 0.05ml. This experiment consisted of using the burette, volumetric pipette, graduated cylinder and beaker to measure the volume of different masses of water. These measurements resulted in data that was used to calculate the density of the water, its average density, and the standard deviation (only with graduated cylinder and beaker.). DATA & RESULTS Part 1: Burets and Titrations Data Table Mass recorded of 50 mL beaker without water (g) (Initial mass) Mass recorded of 50 mL beaker with water (g) (final mass) Mass of water Empty Beaker 28.495g 5 mL water total 28.495g 33.955g 33.955g -28.495g =5.460g 10 mL water total 28.495g 39.005g 39.005g-28.495g =10.510g 15 mL water total 28.495g 43.944g 43.944g- 28.495g=15.499g This Data Table contains the measurements of water placed in a beaker in increments of about 5 ml. The recorded data was used to find the mass of the water by subtracting the initial mass of the beaker from the final mass of the beaker plus the water. Burette initial volume: 50.00ml

Burette final volume: 35.00ml Density Calculation Density = mass / volume. d 1 = 5.46 g 5.0 ml = 1.1 g / ml d 2 = 1.1 g / ml d 3 = 1.0 g/ml Averagedensity = d 1 + d 2 + d 3 3 Averagedensity = 1.1 g / ml + 1.1 g / ml + 1.0 g / ml 3 = 1.06 g / ml = 1.1 g / ml Part 1 questions: 1. How many significant figures should you use with a burette? Why? When recording data from the burette, two decimal spaces are required. The burette measures up to the closest 0.05ml. 2. What is the approximate mass of 1 mL of water? Water has a density of 1g/ml, meaning that for every milliliter of water, its mass is 1 g. 3. When changing solutions, should you wash the buret? Why? The burette must be cleaned each time its used. Having residual solutions on a burette can affect the final desired product and or/ dilute the desired solution. For this reason, burettes must be cleaned when changing solutions. 4.When changing solutions, what would you use to wash the buret? Why? Burettes must be cleaned with deionized water. Regular tap water will have minerals and other compounds. Deionized water does not contain any ions that can contaminate the next solution to be poured in.

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Part 2: Volumetric Pipettes Data Table Solution Mass recorded of 50 mL beaker without water (g) (Initial mass) Mass recorded of 50 mL beaker with water (g) (final mass) Mass of water (g) 10mL water 28.848g 38.682g 38.682g-28.848g = 9.834g 10 mL water 28.848g 38.783g 38.783g-28.848g = 9.935g 10 mL water 28.848g 38.797g 38.797g-28.848g = 9.949g This Data Table contains the data recorded from adding approximately 10ml of water to a beaker with a volumetric pipette. The data was used to calculate the exact mass of the water and its density. Density Calculation Density = mass / volume. d 1 = 9.839 g 10.0 ml = 0.98 g / ml d 2 = 0.99 g / ml d 3 = 0.99 g/ml Averagedensity = d 1 + d 2 + d 3 3 Averagedensity = 0.98 g / ml + 0.99 g / ml + 0.99 g / ml 3 = 0.986 g / ml = 0.99 g / ml Part 2 Questions:

1. How can you get the bottom of the meniscus to the volumetric line of the pipette? By releasing water from the burette until the bottom of the meniscus aligns with the pipette lines. 2. Do you use the bulb to help dispense the liquid from the pipette? Why or why not? The bulb helps to create the vacuum that allows water to be aspirated into the pipette. Instead, a mechanical release is used to allow for a controlled and precise release of water. 3. How many significant figures should you use with a pipette? Why? Four significant figures are used with 2 decimal spaces. This was done this way because the most precise measurement that can be done with the pipette is up to 0.05ml. 4. What is the approximate mass of 1 mL of water? Water has a density of 1g/ml, meaning that for every milliliter of water, its mass is 1 g. 5. When changing solutions, should you wash the pipette? Why? Pipettes must be cleaned each time it’s used. Having residual solutions on a burette can affect the final desired product and or/ dilute the desired solution. For this reason, Pipettes must be cleaned when changing solutions. 6. When changing solutions, what would you use to wash the pipette? Why? Pipettes must be cleaned with deionized water. Deionized water because since it does not contain any ions that can contaminate the next solution to be poured in. Part 3: Graduated Cylinder Data table Solution Mass recorded of 50 mL beaker without water (g) (Initial mass) Mass recorded of 50 mL beaker with water (g) (final mass) Mass of water (g) 10mL water 28.515g 38.062g 38.062g-28.515g = 9.547g 10 mL water 28.515g 38.062g 38.062g-28.515g = 9.547g

10 mL water 28.515g 38.062g 38.062g-28.515g = 9.547g Density Calculation Density = mass / volume. d 1 = 9.547 g 10.0 ml = 0.9547 g / ml =0.955g/ml d 2 = 0.955 g / ml d 3 = 0.955 g / ml Averagedensity = d 1 + d 2 + d 3 3 Averagedensity = 0.955 g / ml + 0.955 g / ml + 0.955 g / ml 3 = 0.955 g / ml Standarddeviation = d 1 − Average density Standarddeviation = 0.955 g / ml − 0.955 g / ml = ¿ 0 Part 3 Questions: 1. How many significant figures should you use with this graduated cylinder? Why? As with the volumetric pipette, Four significant figures were used and 2 decimal spaces. The most precise measurement that can be done with the graduated cylinder is up to 0.05ml. 2. What is the approximate mass of 1 mL of water? Water has a density of 1g/ml, meaning that for every milliliter of water, its mass is 1 g. 3. When changing solutions, should you wash the graduated cylinder? Why? The graduated cylinder must by cleaned in between changing solutions to avoid contamination and possible dilution of the new solution. 4. When changing solutions, what would you use to wash the graduated cylinder? Why? Deionized water because since it does not contain any ions that can contaminate the next solution to be poured in. 5. Do you think making measurements in triplicate is a good practice in the lab? Why or why not? Explain your reasoning.

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Part 4: Beakers Data Table Solution Mass recorded of 50 mL beaker without water (g) (Initial mass) Mass recorded of 50 mL beaker with water (g) (final mass) Mass of water (g) 10mL water 28.850g 37.305g 37.305g-v28.850g=8.455g 10 mL water 28.850g 37.305g 37.305g-v28.850g=8.455g 10 mL water 28.850g 37.305g 37.305g-v28.850g=8.455g Density Calculation Density = mass / volume. d 1 = 8.455 g 10.0 ml = 0.846 g / ml d 2 = 0.846 g / ml d 3 = 0.846 g / ml Averagedensity = d 1 + d 2 + d 3 3 Averagedensity = 0.846 g / ml + 0.846 g / ml + 0.846 g / ml 3 = 0.846 g / ml Standarddeviation = d 1 − Average density Standarddeviation = 0.846 g / ml − 0.846 g / ml = ¿ 0 Part 4 Questions: 1. How many significant figures should you use with a beaker? Why? Two significant figures. The beaker is only used for rough estimates and not for exact measurements like the pipette or the graduated cylinder.

2. What is the approximate mass of 1 mL of water? Water has a density of 1g/ml, meaning that for every milliliter of water, its mass is 1 g. 3. When changing solutions, should you wash the beaker? Why? The beaker must be cleaned when introducing a new solution to avoid contamination or dilution of the new solution. 4. When changing solutions, what would you use to wash the beaker? Why? Deionized water because since it does not contain any ions that can contaminate the next solution to be poured in. 5. Do you think making measurements in triplicate is a good practice in the lab? Why or why not? Explain your reasoning. Making measurements triplicate is a good practice in the lab; getting consistent results in measurements reaffirms that a phenomenon is being recorded and it’s not something happening at random. ADDITIONAL DATA TABLE Lab equipment Volume Average Density Standard deviation Burette 50.00ml 1.1 g / ml Volumetric Pipette 10.00mL 0.99 g / ml Graduated Cylinder 10.00mL 0.955 g / ml 0 Beaker 10mL 0.846 g / ml 0 Conclusion The objective of this experiment was to familiarize with the basic measurement units for volume and mass used in chemistry, grams, and milliliters. Since the density of water is 1g/ml, it is easy to calculate proportions and percentages as for each millimeter of water, its mass should be 1 gram. It also introduces the basic equipment and its proper handling. By the data recorded it was shown that the beaker is the least accurate instrument to measure liquids; the results of the water density were 0.846 g / ml , the actual water density is 1g/ml. The result of the calculations showed that the burette, volumetric pipette, and the graduated cylinder are most appropriate for accurate measurements of liquids.

Citations “Beaker.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam- webster.com/dictionary/beaker. Accessed 20 May. 2024 . Britannica. "Burette." Britannica , www.britannica.com/science/volumetric-analysis. Accessed 19 May 2024. “Pipette.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/pipette. Accessed 20 May. 2024. “Graduated cylinder.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/graduated%20cylinder. Accessed 20 May. 2024. “What is it in tobacco that makes it so dangerous? There are more than 4,000 chemical compounds in every cigarette that are hazardous to your health. Nicotine, for example, acts as a high- powered stimulant that raises blood pressure and heart rate. It is one of the most addictive drugs in the market. Its addiction is comparable to heroine or morphine. Nicotine causes irritation to the lining of the blood vessels. This may cause the "bad" LDL cholesterol to adhere to the vessel walls and speed hardening of the arteries (arteriosclerosis). Hardening of the arteries can eventually lead to a heart attack or stroke. At least 40 of these chemicals in cigarettes are known to cause cancer in humans. When a cigarette is smoked, nicotine first enters the lungs and bloodstream. Within seven seconds, about 15 percent of the nicotine travels directly to the brain. Each puff provides the smoker with a dose of nicotine. Not all the smoke from a cigarette goes into the lungs of the

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smoker; a large part is exhaling into the air. This creates an atmosphere of smoke for other people to breath. This is known as second-hand smoke. How dangerous is second-hand smoke? Second-hand smoke is more dangerous because it is not filtered out and goes straight into the air. More than 5000 toxins spread through the air into other people’s lungs. Seven out of the top 20 more toxic chemicals are found in cigarettes. An estimate of 3000 deaths per year is attributed to second-hand smoke. Second-hand smoke is classified as a human class A carcinogen by the Environmental Protection Agency (EPA), a fact not a probability. In this experiment we will determine the effect of direct (1st hand) and indirect (2nd hand) smoke by collecting the solids released while simulating the process of smoking.”