1

answer

0

watching

175

views

10 Nov 2019

A quantitative analysis for an analyte gives a meanconcentration of 12.6 ppm. The standard deviation for the method isfound to be 1.1 ppm, and that due to sampling is 2.1 ppm.

a. What is the overall variance for the analysis?

b. By how much does the overall variance change if sm isimproved by 10% to 0.99 ppm?

c. By how much does the overall variance change if ss isimproved by 10% to 1.9 ppm?

1

answer

0

watching

175

views

For unlimited access to Homework Help, a Homework+ subscription is required.

You have 0 free answers left.
Get unlimited access to 3.8 million step-by-step answers.

Get unlimited access

Already have an account? Log in

Beverley SmithLv2

28 Oct 2019

Unlock all answers

Get 1 free homework help answer.

Already have an account? Log in

Join us on Discord

Chemistry Study Group

Related textbook solutions

Basic Chemistry

ISBN: 9780134138046

Principles of Chemistry Molecular Approach

ISBN: 9780134112831

Chemistry: Structure and Properties

ISBN: 9780134293936

Principles of Chemistry Molecular Approach

3rd Edition, 2014

ISBN: 9780321971944

Chemistry: A Molecular Approach

ISBN: 9780321809247

Chemistry: A Molecular Approach

ISBN: 9780134874371

Principles of Chemistry: A Molecular Approach

ISBN: 9780134895741

Chemistry: The Central Science

14th Edition, 2017

ISBN: 9780134414232

Related questions

1.) Please match each statement to the best available keyword or phrase provided. Note that there are more keywords and phrases then needed for the sentences available.

[ ] NOx and Sox in our atmosphere forms _________.

[ ] The movement of water to continually expose fresh surface area for water to interact with O2 in the air determines the ________ of O2 dissolution in water.

[ ] This example of tire pressure change with temperature is a direct application of the _________.

[ ] The two most common oxidizer in natural waters is _________.

[ ] One would expect the concentration of any dissolved gas in aqueous solution to _______ as temperature increases.

[ ] During the winter months, your car tires will need some inflation due to the fact that as temperature goes down, the pressure will go ______ if all else is constant.

[ ] The ________ of O2 dissolution in water is determined by temperature.

a. acid rain

b. decrease

c. down

d. Ideal Gas Law

e. increase

f. CO

g. CO2

h. kinetics

i. OH

j. OOH

k. O2

l. thermodynamics

m. up

2.) Explain why there is more than one Lewis Structure possible for C9H12. Describe a Lewis Structure for C9H12 that is non polar.

3.) How (name specific mechanisms in water, air, or soil) is non-polar C9H12 most likely to migrate through our environment on Earth?

4.) Is it possible to convert to NO to N2O in our atmosphere? Why or why not?

5.) If a compound has a log Kow value of 6.5, what would be its predicted concentration in the fat of fish that swim in water containing 0.00003 ppm of that chemical?

a. 1 ppm

b. 10 ppm

c. 40 ppm

d. 55 ppm

e. 95 ppm

6.) A cubic meter of air sample was sampled at 1.0 atm and 20C. An analysis of that sample found it to contain 203 micrograms of NO2. How many ppb of NO2 is in that air?

PROBLEM s - Report your answers on a separate piece of paper The following samples were collected using active sampling on adsorbent sampling media and reported to you as a weight in ug. Calculate the concentration for each of the contaminants in Sample Weight of the Sampling time Pump Exposure concentration in mg/m chemical in in flow rate minutes s0o Ëäº¿ 50 500 0.01 2. Convert 0.01% by volume into parts per billion(ppb). 3, Convert 0.01% by volume into ppm. How many ãare in 50mg?5000) 4. 5. You decide to use the impinger method to sample formaldehyde gas exposure in a medical technologist in a pathology department. You set the pump for 150ml per min and sample for cã 8 hours. According to the lab report, the average concentration of formaldehyde in the solute 1 , (collection liquid) was 100 Î¼gml in 15 ml of solute. Calculate the medical technologist's esposure in ppm. The molecular weight of formaldehyde is 30.0 g/mole. 6pp 6. In the lab where we sampled particulates, the pumps were set at a flow rate of at least 2 lpm What is the main reason why collection of gases and vapors requires relatively slower flow rates than particulate sampling methods? When connecting a sorbent tube to the end of the sampling train, which end points towards the pump? a) 7. the primary chamber b)) the backup chamber it does not matter 8. You use an adsorbent tube to monitor a worker for exposure to toluene solvent vapors. The pump flow rate was 10 ml per min, and the sample time was 480 minutes. The laboratory reports there is 300 Î¼g in the primary chamber of the tube and 30 Î¼g in the backup chamber. What was the worker's exposure in ppm? The molecular weight for toluene is 92.1 g/mole and the specific gravity is 0.87 9. If you are using an explosimeter and you are sampling for a gas with a lower explosion limit (LEL) of 1.0% by volume, what is the approximate concentration of the gas in ppm, if the meter gives a reading of 20% of the LEL? 10 How many Î¼1 of acetone (SG=0.79 and Mw-58) must evaporate in a 10-liter plastic bag to achieve a concentration of 500ppm? 11. Using a sorbent tube, you sampled turpentine vapor for 8 hours at 50 ml per minute According to the laboratory analysis, there was a concentration of 0.1% by volume in 15 ml of 135

How is the binding of F- to cations minimized in your experiment.

CHEM 319, QUANTITATIVE ANALYSIS LA8ORATORY EXERCISE à¸®6 QUANTIFYING FLUORIDE USING AN ION SELECTIME ELECTRODE PRE-LAD READING Read Harris pages 303-306 311-317 (on-selective electrodes) Lean how to prepare samples for analysis from dmicut to wark with starting materials Learn how to prepare calibration curves from ISE data EXPERIMENT OVERVIEW For this lab, you will determine the fuoride content in commercial mouthwashes using an ion selective electrode. This lab uses the direct potentiometry method, which assumes that matrix interferences are not a problem for determining the concentration of fuoride in toothpaste. To combat possible matrx problems, the total ionic strength adjustment buler (TISAB) solution used in the experiment contains 12 gand ensures that cations of meta's such as iron and copper in the sample will not complex the fuoride on. The TISAB will also adjust and stablize the lonic strength of the measured solutions lonic strengt can be a large factor affecting accuracy in ion selective electrode (ISE) measurements MATERIALS Total ionic strengh adjustment bulffer (TISAB) Fluoride stock solution (500 ppm wv) Two commercial mouthwashes (one control and one unknown) Fluoride lon selective electrode 10 mL volumetric fasks Sar bars 20-mL vials 1. Prepare five 10 mL standard solutions (2 ppm. 5 ppm, 20 ppm. 50 ppm, and 100 ppm)each containing 50%w/v ofthe TISAB andthe residual volumne comprised of D' water Transfer these standards to abeled 20-mL viais. 2. In a 10mL vourmetric flask, prepare a sample that contains 1.00 mL mohash and 50% vv TISAB The solution will be quite foamy, so take care not to add the TISAB and Dil water too vigorously. You may also want to add the TISAB and some of the DI water prior to adding the mouthwash (be sure that you do not overshoot the mark, though). Mix well. Repeat for the other mouthwash sample. Transfer these samples to labeled 20-m vials 3. When all of your samples are prepared, add a small magnetic stir bar to the sample to be measured Put the vial onto strplate and carefully lower tuonde eectode the solton Record the potential (in mV). Remove the stir bar and wipe it dry with a Kimwlpe. Repeat for each standard and Prepare a calibration curve from your data (see page 313 of your textbook about how to do so) and use it to determine the concentration of your unknown and control samples. From these caiculated concentrations, determine the % wiv of fuoride in each sange not, that this reported as Neper 100 mL solution. You should also report the mg of NaF per 10 mL dose The waste generated from this lab can be safely washed down the drain. Data Determincd Table I of Solutions AB ( 50%) 0 rem Table 2: Data Determined pem 0 ppm 0 ppen 100 ppm 0 mV 5.3 mV 1 mV 18.0 mV 0 mV 74 mV

Show transcribed image text CHEM 319, QUANTITATIVE ANALYSIS LA8ORATORY EXERCISE à¸®6 QUANTIFYING FLUORIDE USING AN ION SELECTIME ELECTRODE PRE-LAD READING Read Harris pages 303-306 311-317 (on-selective electrodes) Lean how to prepare samples for analysis from dmicut to wark with starting materials Learn how to prepare calibration curves from ISE data EXPERIMENT OVERVIEW For this lab, you will determine the fuoride content in commercial mouthwashes using an ion selective electrode. This lab uses the direct potentiometry method, which assumes that matrix interferences are not a problem for determining the concentration of fuoride in toothpaste. To combat possible matrx problems, the total ionic strength adjustment buler (TISAB) solution used in the experiment contains 12 gand ensures that cations of meta's such as iron and copper in the sample will not complex the fuoride on. The TISAB will also adjust and stablize the lonic strength of the measured solutions lonic strengt can be a large factor affecting accuracy in ion selective electrode (ISE) measurements MATERIALS Total ionic strengh adjustment bulffer (TISAB) Fluoride stock solution (500 ppm wv) Two commercial mouthwashes (one control and one unknown) Fluoride lon selective electrode 10 mL volumetric fasks Sar bars 20-mL vials 1. Prepare five 10 mL standard solutions (2 ppm. 5 ppm, 20 ppm. 50 ppm, and 100 ppm)each containing 50%w/v ofthe TISAB andthe residual volumne comprised of D' water Transfer these standards to abeled 20-mL viais. 2. In a 10mL vourmetric flask, prepare a sample that contains 1.00 mL mohash and 50% vv TISAB The solution will be quite foamy, so take care not to add the TISAB and Dil water too vigorously. You may also want to add the TISAB and some of the DI water prior to adding the mouthwash (be sure that you do not overshoot the mark, though). Mix well. Repeat for the other mouthwash sample. Transfer these samples to labeled 20-m vials 3. When all of your samples are prepared, add a small magnetic stir bar to the sample to be measured Put the vial onto strplate and carefully lower tuonde eectode the solton Record the potential (in mV). Remove the stir bar and wipe it dry with a Kimwlpe. Repeat for each standard and Prepare a calibration curve from your data (see page 313 of your textbook about how to do so) and use it to determine the concentration of your unknown and control samples. From these caiculated concentrations, determine the % wiv of fuoride in each sange not, that this reported as Neper 100 mL solution. You should also report the mg of NaF per 10 mL dose The waste generated from this lab can be safely washed down the drain. Data Determincd Table I of Solutions AB ( 50%) 0 rem Table 2: Data Determined pem 0 ppm 0 ppen 100 ppm 0 mV 5.3 mV 1 mV 18.0 mV 0 mV 74 mV

Weekly leaderboard

Homework Help 3,900,000

Chemistry 830,000

Start filling in the gaps now

New to OneClass?Sign up