Lab #1 Name: Lab #1: Introduction to Lab Techniques INTRODUCTION Our goals in this experiment are (1) to make some measurements using a metric ruler, (2) to learn how to determine volumes with a graduated cylinder, and (3) to determine the density of an unknown liquid and an unknown solid. PROCEDURE Part A: The Metric Ruler i) On the image of the metric ruler below, draw a small arrow pointing to 2.00 cm and write “A”, do the same and write “B" at 12.00 cm, "C" at 3.50 cm, "D" at 8.55 cm, and “E" at 10.60 cm. NOTE: The numbers that are displayed are cm, the increment is 0.1 cm. A C D D D E D B D ii) Use a metric ruler to determine the length and width of this piece of paper. Metric rulers are on the counter in the back of the lab. Use the correct number of decimal places based on the ruler increment (as you did in the pre-lab). Increment on metric ruler = 0.1 cm Length of the page = 69.5 cm Do calculations to convert the length of the page to mm and meter (show your calculations for full credit) cm to mm 69.5 cm 10 mm 1 cm = 695 mm cm to m 69.5 cm 1m 100 cm = 0.695 m = 695 mm = 0.695 m. Width of the page = 18.9cm 1 Lab #1 Do calculations to convert the width of the page to mm and meter (show your calculations for full credit) cm to mm 18.9 cm 18.9 cm 69.5 cm 10 mm 1 cm cm to m 1m = 189 mm = 0.189 m 100 cm = 198 mm = 0.189m. Part B: The Graduated Cylinder There are three graduated cylinders set up in the lab. Each line on the 1000mL graduated cylinder represents ten milliliters (note that 1000 mL = 1 L). Each line on the 100mL graduated cylinder represents one milliliter. Each line on the 10 mL graduated cylinder represents 0.1 milliliters. Observe the top of the liquid in the 100 mL cylinder. Note that the liquid surface is curved, not level. The curved surface is called the meniscus. The volume is always read at the lowest point of the meniscus. Hold the graduated cylinder so the meniscus is exactly at eye level. Now raise and lower the graduated cylinder and observe that the volume reading changes as the cylinder is raised and lowered. Only when your eye is at exactly the same level as the bottom of the meniscus can you obtain an accurate volume reading. (The error introduced if your eye is high or low is called parallax.) Using the correct number of decimal places (as you did in the pre-lab), determine the volume of liquid in each of the 3 cylinders and record the data below. Graduate Cylinder Increment of Graduated Cylinder 10 mL Volume of Liquid in Cylinder 300mL 1 mL 30 ml 1000 mL (= 1L) 100 mL 10 mL Remember to use units whenever you write a number. 2 Lab #1 Part C: Measuring the Density of a Solid 1) Each student will be given a metal cylinder, record the unknown number in the data table below. 2) Weigh the metal cylinder, record the mass (in data table below) to at least three places past the decimal point. 3) Determine the increment of the 100 mL graduated cylinder and record it in the table below. 4) Place about 30 ml of water in your 100 mL graduated cylinder, record the volume to one decimal place more precise than the increment (as done in pre-lab) in the data table below. 5) While holding the graduated cylinder at an angle, carefully slide your metal slug into the graduated cylinder. The metal cylinder must be completely submerged. Record the new volume in the data table below to one decimal place more precise than the increment. DATA TABLE Metal Cylinder: Unknown number: 4a Mass of metal: 121.221g Increment on a 1000 ml graduated cylinder 10 mL (Figure it out just as you did on the prelab or ruler) Volume before submersion of metal 300mL (report volume to one decimal place more precise than the increment) Volume after submersion of metal 350mL (report volume to one decimal place more precise than the increment) 6) Calculate the volume of your metal cylinder. Use the data above and the “volume by displacement method” as discussed in the powerpoint prelab introduction to calculate the volume of the metal. Volume of displacement = Volume final – initial volume = 350 – 300 = 50 mL = 50 mL 7) Go to page 5 and calculate the density of your metal cylinder. Show your calculations, using the correct number of significant figurers in the appropriate box on page 5. 3 Lab #1 DATA TABLE Metal Cylinder: Unknown number: 4b Mass of stone: 14.459 g Increment on a 100 ml graduated cylinder 1 mL (Figure it out just as you did on the prelab or ruler) Volume before submersion of metal 30mL (report volume to one decimal place more precise than the increment) Volume after submersion of metal 35mL (report volume to one decimal place more precise than the increment) 8) Calculate the volume of your metal cylinder. Use the data above and the “volume by displacement method” as discussed in the powerpoint prelab introduction to calculate the volume of the metal. Volume final – initial volume = 35 – 30 = 5 mL = 5mL 9) Go to page 5 and calculate the density of your metal cylinder. Show your calculations, using the correct number of significant figurers in the appropriate box on page 5. 4 Lab #1 DENSITY CALCULATIONS In the boxes below, calculate the densities of the metal cylinder and the unknown liquid. Remember: Every number in a measurement must have a number and a unit) i) Calculation of the unknown solid’s density (4a) density = mass volume = 121.221g 50mL = 2 g/mL (1 s.f) Unknown solid number 4a Density of your unknown solid: 2 g Did you use the correct number of significant figures? yes ii) Calculation of the unknown solid’s density (4b) density = mass volume = 14.459g 5mL = 3 g/mL (1 s.f) Unknown liquid number 4b Density of your unknown liquid: 3 g/mL Did you use the correct number of significant figures? yes END OF LAB #1 5