120 likes | 546 Views
Reading Graduated Cylinders. Important Stuff!. Graduated cylinders are used to measure the volume of liquid samples and are available in many different sizes. . Reading the Volume from a Graduated Cylinder. Determine the gradation markings on the GC.
E N D
Reading Graduated Cylinders Important Stuff!
Graduated cylinders are used to measure the volume of liquid samples and are available in many different sizes.
Reading the Volume from a Graduated Cylinder • Determine the gradation markings on the GC. • Determine the volume contained in a graduated cylinder by reading the bottom of the meniscus at eye level. • Read the volume using all certain digits and one uncertain digit. • Certain digits are determined from the calibration marks on the cylinder. • The uncertain digit (the last digit of the reading) is estimated.
Depending on the size of the graduated cylinder and the graduations, the uncertain digit may be to the milliliter ( 1X ), the tenth of a milliliter ( 1.X ), or the hundredth of a milimeter ( 1.1X ). You will have to look at the graduated cylinder to determine how many digits to record!
Steps in brief… • Step 1: Determine the scale increment: • To find the scale increment, subtract the values of any two adjacent labeled graduations and divide by the number of intervals between them • Step 2: Use the graduations to find all certain digits: • Use the labeled graduations and the scale increment to find the certain digits in the measurement. • Step 3: Estimate the uncertain digit and obtain a reading: • Estimate the distance that the meniscus lies between the two graduations as a decimal fraction and multiply by the scale increment
Looking at a 10 mL cylinder • What is the volume you should record for the solution in the image to the right? • 6.31 mL correct • 6.3 incorrect • WHY?
Looking at a 25 mL cylinder • What is the volume you should record for the solution in the image to the right? • 21.50 mL correct • 21.5 incorrect • Why?
Looking at a 100 mL cylinder • What is the volume you should record for the solution in the image to the right? • 52.8 mL correct • 53 mL incorrect • Why?