Being able to accurately measure masses and volumes of various substances and choosing the best possible instrument to be able to make the most accurate measurements possible is vital.
Knowing the relative accuracies of various tools will help us make informed decisions later on about which would be the best tool to use in a given situation, and we will have a better idea of how accurate our measurements and the results that follow are. This lab is to help us become familiar with making measurements and the equipment available in the lab. We will do this by finding the density of water and ethanol, and a copper sulfate solution. We will also have a chance to become familiar with Excel and using it to record and organize data. We are trying to answer questions such as: How accurate are the various tools we have available to us? What instruments are available to us? How consistent are our results? How do measurements vary from one person to another? Are we doing the experiment in a way that others can replicate the process? It is important that these questions be answered because it will give us the knowledge to proceed with future labs. We will leave with the information that will enable us to make informed decisions about what tools to use in future labs. In order to answer these questions we will measure out a specified amount of water in milliliters and then find the mass.
We will do this with three different tools, then we will compare the results to see which instrument was the most accurate and consistent. We will then measure out specified amounts of ethanol in milliliters and find the mass in order to determine the density of ethanol. We will then measure out in dreams copper sulfate and create a ten milliliter solution with the various amounts, find the mass in grams of the solutions and find the densities of the solutions.
Materials-RO Water-Ethanol-Copper Sulfate-Micropipette-10 mL graduated cyliner-50 mL graduated cylinder-10 mL beaker-10 mL Volumetric Flask -Scale -Weigh boat -100 mL beakerMethods Part A -Pick 3 tools to measure 1 mL of water. Measure out 1 mL of water, with each tool 4 times, each time measuring the mass of the 1 mL. Find the averages and standard deviations for each tool. Repeat this process measuring for 4 mL, and again for 10 mL. Use the resulting standard deviations and averages to determine which is the best tool for each volume. Part B – Using the tools you determined were best measure out 1, 2, 4, and 10 mL of water. Each time measure the mass of the water and record you results, do this 4 times for each measurement again.
For 1, 4, and 10 mL you can use the best results from part a. Calculate the averages and standard deviations. Use these measurements to determine the density of water, which can be done by graphing average mass on the Y-axis and average volume on the X-axis in a scatterplot and then finding the line of best fit, the slope of the line will be the density. Repeat all of this with ethanol. Part C -Add copper sulfate to water. Using the volumetric flask make a solution of 1.
0 gram of copper sulfate per 10 mL of total solution. Measure the density of the solution by measuring the mass and dividing that by the volume. Using the volumetric flask again make a solution of 0.75 grams of copper sulfate per 10 mL of total solution. Find the density again.
Make a solution of 0.50 grams of copper sulfate per 10 mL of total solution, measure the density. Make a solution with 0.25 grams of copper sulfate per 10 mL of total solution. Find the density of this solution too.