Lab Measurements

Mass of product 1.68 g 1.68 g 22.65 g 31.58 g 42.21 g 51.43 g 61.95 g What is the average mass, in grams, of the product based on the six trials?

1.92

Determine the number of significant figures in each measurement. Then, choose the representation of the number where x is in place of the estimated digit from the measurement. 14.8m $10.25 0.005L 1.000g/mL 6200cm 403kg

3 & 14.x 4 & 10.2x 1 & 0.0x 4 & 1.00x 2 & 6x00 3 & 40x

A series of measurements in the lab led to an experimental result of 32.9 mL, with a calculated standard deviation of 0.3 mL. What is the standard way to report this result?

32.9 ± 0.3 mL

When drawing up liquid into a micropipette, put the tip in the liquid at a_________ degree angle, push the plunger to the______ of resistance, and then_______the plunger. When dispensing that liquid from the micropipette, hold the micropipette at a_____________ degree angle in the desired container and push the plunger to the __________ point of resistance. ___________the plunger until dispensing is done.

90 1ST Release 45 2nd Hold Down

Select the correct value for each letter to complete the formula for percent error. In order to calculate the percent error, you need to know the accepted value and the experimental value. A=|accepted value−B|/C ×100

A= percent error B= experimental value C= accepted value

When describing the uncertainty of a measurement, the term ___________________ refers to the closeness between a measurement and its accepted value, whereas the term ______________________ refers to the closeness among a set of measurements.

Accuracy Precision

When inputting a formula into Excel or other spreadsheet software, what components are required for the formula to function properly?

An equal sign at the beginning of the formula Closing parentheses for any opening parentheses

How do you determine the last digit in any measured number?

Estimate one digit past the smallest precisely known digit or marking.

Determine whether each quantity is a measured value or an exact value. 144 grams of sugar 2 avocados 2 cups of milk 1 ft = 12 in 18 meters 3 teacups

Measured Exact Measured Exact Measured Exact

Use a new tip any time you change solutions. Place the micropipette on the bench between uses. check_circle_outline Save tips after removal to reuse them later. Place the micropipette on a rack after using it. Turn the micropipette upside down after loading with liquid.

Recommended Not Recommended Not Recommended Recommended Not Recommended

Suppose that two students perform a titration experiment multiple times, resulting in the average concentrations reported here. Student A 0.125 ± 0.008 M Student B0.12 ± 0.03 M The more precise work was done by __________ because _____

Student A The student's data has a smaller standard deviation

Identify the following errors as systematic or random. A few drops of water are on a balance pan, causing the mass output on the balance to be high each time it is used. The last digit on a pH meter fluctuates up and down as a measurement is taken. A micropipet is improperly calibrated, and the balance dispensed is always smaller than expected. A thermometer is placed such that the bulb makes poor contact with the measured substance, giving erratic temperature readings.

Systematic Random Systematic Random

Identify the recommended practices when putting a tip on a micropipette.

Use the tip size designed for the micropipette size in use. Gently push the micropipette into the tip and tap lightly to load the tip.

Systematic error is caused by ____________________, while random error is caused by

improper use of a measuring device random fluctuations in a measuring device