Chemistry Lab 1

1. Which of the following samples may be weighed on an analytical balance without a container? A.glass beads B. dry sand C.paper clips D.sucrose E. all the above 2. Touching the sample container with bare hands without gloves affects the mass recording of an analytical balance due to moisture on the hands. A. true B. False

Estimated volume of crucible 25.0 mL  measured volume of crucible 23.0 mL  percent error of estimate (% error=accepted value-experimental value/accepted value ) volume in (use measured volume of crucibleto answer for the ):  kL cL

Question 3 please. It's a practice exam. Will post the answer with it.

1. a. What are the three classifications of chemicals used in analytical chemistry? (one is Primary Standard Grade) b. What are the three common sources of error encountered in weighing (one is buoyancy) c. To what precision can analytical balances (in mg) and pan balances (in g) be read

Laboratory 2 Report Sheet-Lab 2 A.2 Area Your measurements Length = Width = Area = (Show calculations.) Why could two students obtain different values for the calculated areas of the same rectangle? A.3 Volume of a solid by direct measurement Shape of solid Formula for volume of solid 18 Height Width Another student's measurements Volume of the solid (Show calculations of volume including the units.) Length Diameter (if cylinder) Page 3 of 3 482 words 区

Volumetric measuring devices may be stamped as TD (to deliver) or TC (to contain). Which of the following devices would you expect to be stamped with both TC and TD? a. pipette b. graduated cylinder c. beaker d. Erlenmeyer flask

What is the laboratory equipment that is best suited to accurately measure large volume of liquids? Select one: a. Graduated cylinder b. Erlenmeyer Flask c. Test tube d. Beaker When measuring liquids using a dropper, the greater the surface tension and the greater the surface to which the drop adhere the smaller the drop. Select one: a. False b. True In compounding laboratory, an alternative apparatus for 1 mL pipette is Select one: a. Measuring cylinder b. Test tube c. Burette d. Dropper e. Conical flask

Please help me answer and use pg 31 for questions A1 and A2 and pg 32 just for questions C1- C5 Thank you!   Pg. 31 Density and Specific Gravity              A. Density of Liquids A.1 Density Of water             1. Volume (mL) = ?             2. Mass of graduated cylinder= ?             3. Mass of cylinder + liquid= ?             4. Mass of liquid= ?             5. Density= ?                         (Show Calculations) A.2 Density of an Unknown liquid             1. Type of liquid sample= ?                  Volume of liquid= ?             2. Mass of graduated cylinder= ?             3. Mass of graduated cylinder + liquid= ?             4. Mass of liquid= ?             5. Density= ?                         (Show Calculations) Pg. 32 C. Density Of Solids             1. Mass of solid= ?             2. Initial water level= ?             3. Final water level with solid= ?             4. Volume of solid (3-2)             5. Density of the solid=     g/mL ?                         (Show…

Determine mass of cube. Record mass in Lab Data.

Choose the item that best describes what is being asked. 1. Hydrogen is the best reference material for what substance? a. Potassium b. Iron c. Argon d. Nickle 2. What type of density is determined in vacuum at a specified temperature? a. Absolute density b. Relative density c.None of the choices c.Apparent density 3. What is the other name of the plummet method? a. Graduated cylinder method b. Displacement method c. Specific gravity bottle method d. Westphal balance method 4. What solution is NOT measured by Baumé light? a. Glycerin b. Isopropyl alcohol c. Gasoline d. Benzene 5. What is defined as the ratio of the density of a substance to the density of a given reference material? a. Neither of the choices b.Specific volume c.Specific gravity d. Either of the choices 6. What is defined as the ratio of the mass of an object in air to the mass of equal volume of water at the same temperature? a. Relative specific gravity b. Absolute specific gravity c. None of the choices d.Apparent…

2. What’s the main purpose of the glass shields on an analytical balance? A. To calibrate the balance B. To stop the current C. To keep out pests D. To prevent finger prints from getting on the weigh pan

121 (OL) Lab 3 Den... V Layout Search References Mailings Review View Help 1 2 3 5 6 I i Lynette Maina Commer 7 LE T Chem 121(OL) Lab 3: Density of Common Materials Part C Thickness of Aluminum Foil (For help understanding the calculations read the introduction and procedure) An experiment performed for Part C to measure the length, width and mass of a piece of aluminum foil gave the following data. You will use this data to solve for the thickness of aluminum foil using the equation from Part C in the introduction. Length of foil Width of foil Mass of foil 13.10 cm 9.50 cm 9.745 g Use the data in the table to determine the thickness of your aluminum foil (in cm) using the 2.6989 g/mL for the density of aluminum then convert this value to meters (m) and micrometers (um). Show your work here (use back if necessary). ons: On Accessibility: Investigate F3 F4 W cm K F5 ►11 F6 K H m um DELL F7 F8 Gu F9 Focus BB 5= 57°F Mostly sunny 4/1 F10 F11 F12 PrtScr "T

Standard deviation is an indication of the... a. precision of one measurement b. accuracy of one measurement. c. precision of repeated measurements.

Which of the following is incorrect: a. General steps in quantitative analysis include: Method selection, sampling, sample processing, calibration & measurement. b. Qualitative analytical methods include: gravimetric, volumetric, spectroscopic and electroanalytical methods. c. The first step in sample processing is sample preparation. d. Replication improves the quality of results and their reliability. e. In quantitative analysis there should be a direct proportionality between a measured property and the concentration or amount of substance. Please fill in the spaces one of the following characters (a or b or cor d or e)

1. A beaker cannot be used for measuring the volume of a liquid because _____. a. it is too large b. it is too small c. it is only used for chemical reactions d. it does not have precise measuring lines   2. The best instrument to use to measure volume in the lab is a _____. a. test tube b. graduated cylinder c. flask d. beaker   Please answer question 1 & 2

Make a graph of the average mass vs. year. Make sure axes are labeled. Please please answer super fast please answer as fast as possible

80. Comment on the accuracy and precision of the data collected about these basketball free-throw shooters. a. 99 of 100 shots are made. b. 99 of 100 shots hit the front of the rim and bounce off. c. 33 of 100 shots are made; the rest miss.

How do I solve for the percent value? The sample data calculated the answers but I have no idea how they obtained the percent error values. Calculate sample data #1 with detailed steps.

How is accuracy and precision related to errors incurred in the chemical analysis? Why systematic errors are also called determinate errors? Why random errors are also called indeterminate errors? Give two examples of each of the following sources of errors.             a. Instrumental error             b. Personal error             c. Method/operational error

Jack measured the mass of an empty evaporating dish and watch glass, and weighed approximately 0.5 g of an unknown solid into the evaporating dish.  He then followed the procedure for Lab Exercise 5, and collected the rest of the data in the table below.  Please note that row letters correspond to those found on the data sheet that you will use in lab.  A Mass of empty evaporating dish + watch glass 65.362 g B Mass of dish + watch glass + initial solid 65.864 g C Mass of dish + watch glass + carbonate 65.705 g D Mass of dish + watch glass + chloride 65.716 g  What was the mass (in grams) of the unknown solid that Jack used in his experiment. Report your answer to the correct number of significant figures.

5) How will each of the following experimental errors influence the results of your calculated densities you reported? State whether the error will tend to make your density results too large, too small or unchanged. Explain why this would occur by identifying which measurements would be affected (high or low) and how this would affect the calculated density. a) In method 2, the metal cylinder you used had a number of air bubbles on its when immersed in the water.

Which statement is true?   Question 12 options:    Precision is measured by standard deviation.   Precision is measured by error or relative error.   Accuracy is measured by the standard deviation.

Errors that are independent of the size of the sample being analyzed. " Errors that decrease or increase in proportion to the size of the sample.

When measuring volumes of liquids, precision volumetric graduates with calibration for measuring multiple volumes are available, usually with inscriptions to deliver. Examples of these include the following with the exception of Select one: a. Pipettes b. Syringes c. Conical Graduates d. Burettes For solids in several pieces or powder heavier than and insoluble in water the most convenient to use is the method. Select one: a. Hydrostatic balance b. Lovi's beads c. pycnometer method d. Mohr-Westphal balance Balances not be situated in the following areas Select one: a. On flat areas b. On non-vibrating surface c. In areas of low humidity d. Areas with vents e. In areas without metal chemicals

List which piece of lab equipment would be most useful for each of the following tasks. 1. Hold 50 mL of boiling water. 2. Crush a chunk of chemical into a powder. 3. Heat a beaker of water when a gas line is not available to power any equipment. 4. Measure exactly 42.5 mL of water. 5. Scoop ammonium nitrate out of its container and onto weigh paper to be measured.

17. Alphonse Bertillon (1853-1914) devised the first sci- entific system of using a series of body measurements. 18. Criminal laboratories exist in the United States under the control of various governmental agencies at the and levels. 19. In Melendez Diaz v. Massachusetts, the U.S. Supreme Court addressed the practice of using lieu of in-person testimony by forensic analysts. 20. The of physics, chemistry, and geology for the identification of the crime scene investigation. in of the crime laboratory makes use is responsible for dispatching trained 21. The personnel to the scene of crime for retrieving evidence. 22. The application of science to criminal investigation was advanced by judge in Austria. 23. In Fyre v. United States the set forth, which serves as the criterion for judicial ad- missibility of scientific evidence. a public prosecutor and principle was 24. The U.S. Supreme Court held that in assessing the ad- missibility of new and scientific evidence, the trial judge does…

For the image attached Make a x and y axes graph of the average mass vs. year.

Q3 we dilute unknown sample of 25ml to 100ml And want to find error propagation associated with it. The unknown sample concentration is :1.2984 ppm Error: .1958 Class A 25 ml pipet error : .03ml Class A 100ml beaker : .08 I find the unknown concentration but need error associated with it during dilution process Any hints?

Question 1 and 3 please! Thank you

Experimental calculations!

answer question 1.a… chemistry please answer in 30 minutes

Which of the following pairs is correctly matched? A. beaker: measures volume of liquids B. spatula: scoops out solids C. hotplate: supplies flame D. crucible tongs: holds test tube

please help! use correct sig figs and/or scientific notation! 3 part question:)