Chem Discussion 2-1

Suppose you were measuring out an organic liquid, and some of it is evaporated after you have performed the volumetric measurement while you are weighing out the sample. What effect would this have on the densities you calculated? Will you overestimate or underestimate the density of the liquid? Would this cause poor accuracy, low precision, or both? Explain briefly.

Wallie weighed 3 different cylinders that all looked the same. He noticed that the masses were all different and wondered how much they deviated from the average. Determine the average deviation, in g, of the cylinder masses below. Cylinder Mass (g) 1 31.8 2 31.39 3 31.96

A piece of cardboard is 12.0 cm long, 6.3 cm wide and 0.75 millimeters thick. What is the volume of this piece of cardboard in cubic meters? Enter your answer in the space provided WITHOUT units. Make sure to round your answer to the correct number of significant figures. Please give the number as a normal number, do not use scientific notation.  (In example: a normal number = 4300 instead of the number being in scientific notation as = 4.3 X 103)

2. Do the following calculations and use the correct number of significant figures in your answers. Assume all numbers are the results of measurements. a. 0.208 + 4.9 + 1.11 b. 228 + 0.999 + 1.02 c. 8.543 − 7.954 d.(3.2 × 10−2) + (5.5 × 10−1) (hint: Write in the decimal form first, then add.) e. 336.86 − 309.11 f. 21.66 − 0.02387

Convert 75 miles into meters. (Use the conversion 1.0 km = 0.621 miles and use metric conversions for the rest of the conversions).

Very large and very small numbers are easier to write in scientific notation. For example, the number, 0.0000516 would be written 5.16  10-5 in scientific notation. How would you enter this number in WebAssign using scientific notation to 3 significant figures? (WebAssign uses e-notation for entering scientific numbers, for example, 1.23e-4.)

Read the paragraph below and identify the aspects of the scientific method that best align with each numbered sentence or phrase. Some answer options may be used more than once. The options are observation, theory, hypothesis, revised hypothesis, experiment, and law. The number option is before the period of each sentece. You are preparing to study for your chemistry exam and flip the switch to turn on your desk lamp. You find that the light does not come on (1). Based on past experiences, you guess that your roommate unplugged the lamp to use their hair drier and forgot to plug the lamp back in (2). You look under the desk and see that the lamp is plugged in (3). You decide instead that the lightbulb must be burned out (4) but you find that the light won’t turn on with a new lightbulb, either (5). You decide that the lamp is broken (6).

I submitted this question just a bit ago and I received an answer that totally makes sense ......  2.5 x 10^-9 Yet my textbook is saying this answer is incorrect. Can you help me?

2. Identify as true (T) or false (F): Scientific method may never prove a theory to be wrong. Repeat measurements that fall close to the true value are both accurate and precise. There is only energy in the Universe and no matter. The number in the quantity '30 miles' is inexact.

Expressing Errors in Measurement: Scientists often express their uncertainty and error in measurement by giving a percent error. The percent error is defined as: % error actual value - measured value x 100 actual value Answer the following four questions. Pay attention to significant figures, and show your work! 1. While doing a lab, a student found the density of a piece of pure aluminum to be 2.85 g/cm°. The accepted value for the density of aluminum is 2.70 g/cm³. What was the student's percent error? 22.70 26 Demystifying Scientific Data: RET 2006, Rev 2

Osmium (Os) is the densest element known (density = 22.57 g/cm3). Calculate the mass in pounds and in kilograms of an Os sphere 15 cm in diameter, about the size of a grapefruit. Enter your answers in scientific notation.

A substance with a density of 2.70 g/mL occupies a volume of 21.3 mL. What is the mass of the sample? Report your answer in units of mg. Do not enter "mg" as part of your answer. Respond with the correct number of significant figures in scientific notation (Use E notation and only I digit before decimal e.g. 2.5ES for 2.5 x 10)

1) The weight of a rock is measured to be 0.075 lbs. After placing the rock in a graduated cylinder containing 17.09 mL of water, the new measurement is 28.76 mL. Calculate the density of the rock in g/mL. 2) A person measures the velocity of a biker riding in a straight line along a sidewalk using a stopwatch. The time it took for the biker to pass 29 squares on the sidewalk was 11.29 seconds. The area of the squares on the sidewalk was measured to be 2731 in2. Calculate the velocity of the biker in m/s.Note: 1 in = 2.54 cm 3) A hollow square metal tube has a measurement of 1.98 in for each side and a weight of 60.92 g. The volume of empty space inside the tube was measured to be 2.44 in3. If the density of the metal used in constructing the tube is 11.46 g/mL, calculate the length of the tube in inches.Note: 1 in = 2.54 cm, 1 cm3 = 1 mL 4) Porosity is a measure of the void or empty spaces in a material and is a fraction of the volume of voids over the total volume. The density of the…

A piece of cardboard is 12.0 cm long and 6.3 cm wide. What is the area of this piece of cardboard in square millimeters? Enter your answer in the space provided WITHOUT units. Make sure to round your answer to the correct number of significant figures. Please give the number as a normal number, do not use scientific notation.  (In example: a normal number = 4300 instead of the number being in scientific notation as = 4.3 X 103)

The density of a metal is 2.42 g/cm3. How many pounds are in 84.87 in of the metal? (You can use the conversion factor approach. Or, you can convert density in g/cm3 to Ib/in3 and then multiply the result times number of pounds. 2.52 cm = 1 inch 454 g 1 lb Please see 'answers to extra problems' question 10 for hints on how to do this.) You need to write your answer in the box with one number past the decimal. Please don't worry about the sig figs in this case. In these formula problems, the Canvas software will give a variety of questions and each student gets their data with different sig figs. So I just have to choose and sometimes it might seem that one past the decimal is not the correct sig figs. Nonetheless. you have to follow that direction.

The weight of a rock is measured to be 0.072 lbs. After placing the rock in a graduated cylinder containing 18.12 mL of water, the new measurement is 31.75 mL. Calculate the density of the rock in g/mL.

3 3 1 1 3 3 3 Name: CHEMISTRY Accuracy and Precision Look carefully at the measurements. Decide if the measurements are Accurate only, Precise only, Both accurate and precise, or Neither. Use only the letters as answers. Type the letters on the line next to the question number. Accurate only: A Precise only: P Both: B Neither: N Mr. Jones got a python. He brought it to school to show his students. The python was very long. Five classmates measured the length of a python with a flexible tape measure. The true length (true value) of the python was 500 cm. The classmates collected and shared the following measurements shown to the right. 1 Kayla 2 Tyrone 3 Ralph 4 5 Block: Measured length of the Python (cm) 474 475 471 310 400 377 500 502 504 538 538 540 488 504 491 Kayla 472 480 292 356 Tyrone Ralph 498 501 Mark 537 541 Lena 516 506 Mark Lena Decide if the measurements are Accurate only.

An electric current of 155.0 mA flows for 42.0 minutes. Calculate the amount of electric charge transported.. Be sure your answer has the correct unit symbol and 3 significant digits. 0 x10 μ 0 9 X

When adding or dividing measured numbers, we don’t count significant figures. Instead, we look at the precision of the measured numbers. The answer can only be as precise as the least precise measurement.

A metal cylinder weighs 49.999 mg. How many pounds (lb.) does it weigh? Use scientific notation to express your final answer.

Fill in the first missing part of this equation using a UNIT RATIO.  * For example, converting m to cm would require multiplying by the unit ratio: (1cm)/(10-2 m)

How many significant figures are in the following measurement: 0.00204 g Type your answer... Perform the following calculation. Enter the answer with the correct number of significant figure. 8.934+ 37.1 29 Be sure to start your answer with 0.xxxx, not just a decimal place, if appropriate. Ex. Enter 0.244 and NOT.244 Type your answer... Convert 69. kL to uL. Express your answer in scientific notation without writing units. Ex. 0.00222 is entered as 2.22*10^-3. Type your answer...