The homogeneity of the chloride level in a water sample from a lake was tested by analyzing por- tions drawn from the top and from near the bottom of the lake, with the following results in ppm CI: Top 26.30 Bottom 26.22 26.43 26.32 26.28 26.20 26.19 26.11 26.49 26.42 (a) Apply the i test at the 95% confidence level to determine if the means are different. (b) Now use the paired / test and determine whether there is a significant difference between the top and bottom values at the 95% confidence level. (c) Why is a different conclusion drawn from using the paired i test than from just pooling the data and using the normal i test for differences in means?

The homogeneity of the chloride level in a water sample from a lake was tested by analyzing por- tions drawn from the top and from near the bottom of the lake, with the following results in ppm CI: Top 26.30 Bottom 26.22 26.43 26.32 26.28 26.20 26.19 26.11 26.49 26.42 (a) Apply the i test at the 95% confidence level to determine if the means are different. (b) Now use the paired / test and determine whether there is a significant difference between the top and bottom values at the 95% confidence level. (c) Why is a different conclusion drawn from using the paired i test than from just pooling the data and using the normal i test for differences in means?

Fundamentals Of Analytical Chemistry

9th Edition

ISBN:9781285640686

Author:Skoog

Publisher:Skoog

Chapter7: Statistical Data Treatment And Evaluation

Section: Chapter Questions

Problem 7.21QAP

See similar textbooks

Similar questions

A sample may contain any combination of sodium hydroxide, sodium carbonate and sodium bicarbonate with inert matter. A 3.00g sample requires 57.57ml of 0.5N hydrochloric acid to reach phenolphthalein endpoint and a total of 105.4ml of acid was used until the methyl orange endpoint was reached. What is the percentage inerts in the mixture? What is the percentage sodium bicarbonate in the mixture? What is the percentage sodium hydroxide in the mixture? What is the percentage sodium carbonate in the mixture?
An experimental attempt was to convert 2000 cm^3 of a solution consists of 0.96 ethanol into another solution consisting of 0.56 ethanol. If the density of water at the experiment's temperature and pressure is 997 kg/ m^3, How much H2O should be added to the 2000 cm^3 solution? What is the solution's volume after conversion? Given data: In the 0.96 ethanol solution :V ethanol = 0.816 cm^3/g and Vwater = 1.273 cm/g In the 0.58 ethanol solution: V ethanol = 0.953 cm^3/g and :V water = 1.243 cm/g
The mass of a beaker is 5.333g. After 5.00mL of a concentrated hydrochloric acid solution is pipetted into the beaker, the combined mass of the beaker and the hydrochloric acid sample is 11.229g. From the data, what is the measured density of the hydrochloric acid solution?
A mixture of ethanol (ethyl alcohol) and water contains 40.0% water by mass.(a) Assuming volume additivity of the components, estimate the specific gravity of themixture at 20°C. What volume (in liters) of this mixture is required to provide 150 mol ofethanol?(b) Repeat Part (a) with the additional information that the specific gravity of the mixture at20°C is 0.89045 (making it unnecessary to assume volume additivity). What percentage errorresults from the volume-additivity assumption?
A student determines the molar mass of a liquid unknown by the method used in this experiment. She found that the equilibrum temperature of a mixture of ice and water was 1.0 degrees C on her thermometer. When she added 11.1 g of her unknown sample to the mixture, the temperature, after thorough stirring, fell to -3.0 degrees C. She then poured off the solution through a screen into a beaker. The mass of the solution was 90.4 g. Kf=1.86 degrees C/m How much water was in the decanted solution? What did she find to be the molar mass of the unknown liquid, assuming she made the calculation properly?
A student determines the molar mass of a liquid unknown by the method used in this experiment. She found that the equilibrum temperature of a mixture of ice and water was 1.0 degrees C on her thermometer. When she added 11.1 g of her unknown sample to the mixture, the temperature, after thorough stirring, fell to -3.0 degrees C. She then poured off the solution through a screen into a beaker. The mass of the solution was 90.4 g. Kf=1.86 degrees C/m 1. What is the freezing point depression? 2. What is the molality of the unknown solution? 3. How much unknown liquid was in the decanted solution?
Convert 370 ppm of CO2 to μg/m3 at 20oC and 101.325 kPa. Convert 80 μg/m3 of SO2 to ppm at 25oC and 101.325 kPa.
In the determination of molar mass of an unknown substance by ebullioscopic constant, 30 mL of acetone (C3H6O) was placed in a test tube with thermometer and glass tubing and subjected to water bath. Upon boiling, the temperature reads 56 deg C. For the boiling point of unknown-acetone solution, you prepared the solution by mixing 1.60 g of unknown solute in the 30 mL acetone and subjected it again to water bath. The boiling temperature of the solution is 56.68 deg C. The density of acetone = 0.9849 g/mL and the Kb of acetone = 1.67 degC/kg
In the determination of molar mass of an unknown substance by ebullioscopic constant, 30 mL of acetone (C3H6O) was placed in a test tube with thermometer and glass tubing and subjected to water bath. Upon boiling, the temperature reads 56 deg C. For the boiling point of unknown-acetone solution, you prepared the solution by mixing 1.60 g of unknown solute in the 30 mL acetone and subjected it again to water bath. The boiling temperature of the solution is 56.68 deg C. The density of acetone = 0.9849 g/mL and the Kb of acetone = 1.67 degC/kg What is the value for delta Tb or the change in boiling temperature (in degrees Celsius)?
In the determination of molar mass of an unknown substance by ebullioscopic constant, 30 mL of acetone (C3H6O) was placed in a test tube with thermometer and glass tubing and subjected to water bath. Upon boiling, the temperature reads 56 deg C. For the boiling point of unknown-acetone solution, you prepared the solution by mixing 1.60 g of unknown solute in the 30 mL acetone and subjected it again to water bath. The boiling temperature of the solution is 56.68 deg C. The density of acetone = 0.9849 g/mL and the Kb of acetone = 1.67 degC/kg What is the value for delta Tb or the change in boiling temperature (in degrees Celsius)? Final answer must be rounded off to 2 decimal places, and shall NOT have any unit.
In the determination of molar mass of an unknown substance by ebullioscopic constant, 30 mL of acetone (C3H6O) was placed in a test tube with thermometer and glass tubing and subjected to water bath. Upon boiling, the temperature reads 56 deg C. For the boiling point of unknown-acetone solution, you prepared the solution by mixing 1.60 g of unknown solute in the 30 mL acetone and subjected it again to water bath. The boiling temperature of the solution is 56.68 deg C. The density of acetone = 0.9849 g/mL and the Kb of acetone = 1.67 degC/kg - What is the value for delta Tb or the change in boiling temperature (in degrees Celsius)? Final answer must be rounded off to 2 decimal places, and shall NOT have any unit. - How many moles of solute is present in the solution given in the video? Final answer must be rounded off to 2 decimal places, and shall NOT have any units. - What is the molal concentration of the solution? Final answer must be rounded off to 2 decimal places, and shall NOT…
Osmotic pressures are often reported in units of atmospheres or mm Hg. The latter impliesthat the height of a column of liquid can be used as a measure of pressure. This is, in fact, thebasis of the torricellian barometer from which the units of “torr” come. The pressure, P, isrelated to the height of the column by:P = ρghwhere ρ is the density of the liquid, g is the acceleration due to gravity and h is the height. Whatwill be the height (in mm) of a column of aqueous solution with a density of 0.9987 g/mL, if theosmotic pressure of the solution at 25 °C is 1.4 mm Hg? The density of mercury at thistemperature is 13.8 g/mL