Homework answers / question archive / The Mole and Solutions Background In this experiment, you will explore the mole, molar mass, and solution concentrations using household materials

The Mole and Solutions Background In this experiment, you will explore the mole, molar mass, and solution concentrations using household materials

Sociology

Share With

The Mole and Solutions Background In this experiment, you will explore the mole, molar mass, and solution concentrations using household materials. You will be using the coat-hanger balance that you assembled earlier in the semester. In Part One, you will use your hanger balance to compare the masses of samples of an equal number of moles of sugar and salt. In Part Two, you will make an aqueous salt solution (saltwater). In Part Three, you will do serial dilutions of your saltwater solution. Materials Needed: • hanger balance (coat hanger, Ziploc bags, binder clips) • electronic kitchen scale • liquid measuring cup • spoon • small bowls or Tupperware containers • tap water • sugar • salt Notes for Submission Please write this lab in your composition book. Copy down any tables provided. Note any observations, and include responses to questions. Use headings to organize the different sections of the lab. Take photos of lab materials as directed, as well as photos of your written pages. Turn all of these images into a single pdf file, and upload that single file into the Canvas assignment for this lab. Part One: The Mole and Molar Mass (Use clean containers and utensils. You may be tasting some of your materials later.) 1. First check that your hanger balance is level by clipping empty Ziploc bags to both sides and hanging the balance on a doorknob or on the tip of your finger. Remember to clip both bags so that they are equidistant from the center of the hanger. 2. Calculate the number of grams in 0.100 mol table sugar (sucrose, C12H22O11). Show your calculations in your composition book. Tare/zero a small container or bowl on your electronic balance, and then mass out this amount of sugar. 3. Calculate the number of grams in 0.100 mol salt (sodium chloride, NaCl). Show your calculations in your composition book. Tare/zero a small container or bowl on your electronic balance, and then mass out this amount of salt. 4. Pour your sugar sample into one of the bags on your hanger balance, and pour your salt sample into the bag on the other side. Which side hangs lower? Note your observations in your composition book. Take a selfie photo with your sugar and salt samples on your hanger balance, and submit the photo with your lab report. 1 Part Two: Solutions 1. Set your electronic balance to measure masses in grams. Zero/tare the balance, and then place your empty liquid measuring cup on the balance. Record the mass of the cup in a table like the one shown below. 2. Now zero/tare the balance with the cup still on the balance. Add between 3 and 6 grams of salt to the cup. (You may use the salt from the bag in Part One.) Record the mass of salt added in your data table. 3. Take the cup with the salt off the balance, and add tap water to the one-cup mark. Stir to dissolve the salt. 4. Zero/tare the balance, and then put your cup containing salt and water onto the balance. Record the mass. 5. Calculate the mass of the salt and water only, and record the mass in your data table as shown below. 6. Save your saltwater solution for Part Three. Item Empty measuring cup Salt added Salt, water and cup Salt and water only (subtract mass of cup) Mass (g) Part Three: Serial Dilutions 1. Making sure that your saltwater from Part Two is well stirred, take a TINY sip of the solution. Does it taste salty? Record your observations in a table such as the one shown below. 2. Make a one-to-two (1:2) dilution by doing the following. Pour out half of the saltwater solution so that you have just half a cup remaining. Then add fresh tap water to the onecup mark, and stir. 3. Do two more 1:2 dilutions as described in step 2. 4. Taste your final saltwater solution by taking a sip. Does it taste as salty as it did before you did all the dilutions? Record your observations. 5. Take a selfie photo with your final saltwater solution, and submit the photo with your lab report. Item Saltwater solution from Part Two Saltwater solution after three 1:2 dilutions Observations (taste) 2 Post-Lab Questions 1. Calculate the percent mass or % (m/m) of the salt solution you made in Part Two. 2. Calculate the molarity (M) of the salt solution you made in Part Two. Recall that there are exactly 8 fluid ounces (fl oz) per cup and 29.5735 mL per fluid ounce (fl oz). 3. Calculate the percent mass or % (m/m) of the final solution that you had at the end of Part Three. Show all work clearly. You may find it helpful to draw pictures to illustrate the steps that you did in the procedure. 4. Calculate the molarity (M) of the final solution that you had at the end of Part Three. Show all work clearly. You may find it helpful to refer to your drawings from question 3. 3