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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docx

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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.

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:

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