Stats
99% CI
Whats a major issue with gravemetric titrations
co-precipitation in solution
Draw and label the electromagnetic spectrum
placeholder
What must we ensure when we want to make and use a calibration curve
Must be in the linear response region and in the range of the concentrations of the standard
Data: 45.12, 44.62, 44.75, 44.70, 43.99, 44.51, 44.85, 45.00
Sd:0.385
Are there any outliers at a 95% confidence
No
Under what conditions is EDTA most effective for Binding
Basic conditions
What are the three terms of the van Deemter equation? How does each relate to flow rate?
A= multiple paths broadening, independent
B= longitudinal diffusion, indirectly proportional
C= finite rate of mass transfer, directly proportional
Why do we use standard addition?
A block of building material has been carefully machined to undergo tests. Its dimensions and mass are as follows: length = 0.050 ± 0.001 m breadth = 0.100 ± 0.001 m height = 0.040 ± 0.001 m mass = 0.560 ± 0.002 kg
(a) From this data, calculate the density of this material. (b) Find the uncertainty in this value of density and express it as a percentage.
a) 2800 kg/m^3
b) 5.86% or +-160
A teacher gave their students an 8.00 gram tablet that contains magnesium nitrate, Mg(NO3)2 (molar mass = 148.32 g/mol). In order to determine the percentage of magnesium nitrate in the tablet, the students dissolved the tablet in 100. mL of distilled water and add excess sodium phosphate, Na3PO4. After a precipitate is formed, the students filter, wash, and dry the precipitate to completion. The precipitate is measured to have a mass of 3.524 grams. (Note: the precipitate will have a molar mass of 262.84 g/mol)
e) Calculate the percentage of magnesium nitrate in the tablet.
74.6%
Calculate the resolution for two peaks separated by 4.04 s when the average FWHM is 1.26 s. Are these two peaks sufficiently resolved?
R=3.21, yes this is good separation of peaks
A calibration curve was prepared using 7 standards and produced the following regression statistics:
Slope (m) = 4.10
Intercept (b) = 0.08
Standard deviation about regression (sᵧ) = 0.12
Mean concentration of standards (x̄) = 0.50
Σ(xᵢ − x̄)² = 0.280
Number of replicate measurements for unknown (k) = 3
An unknown sample gives an average signal (ȳᵤ) of 2.05.
What is the mean of the sample and 95% confidence interval
0.41 +- 0.05
A biologist is trying to determine the number of oak leaves on a certain species of oak tree. They surveyed 31 different trees and discovered that there is an average of 194,103 leaves on each tree with a standard deviation of 5,404 leaves.
What is the confidence interval of this measurement at the 90% confidence level?
(192,457, 195,749)
A 0.6181 gram sample of M2CO3 was taken and dissolved in enough water to make 100.0 mL of solution A. A 10.00 mL aliquot of solution A was taken and 25.00 mL of 0.1842 M HCl added.
M2CO3(aq) + 2HCl(aq) -> 2MCl(aq) + H2O(l) + CO2(g)
It took 19.90 mL of 0.1473 M NaOH to titrate the resulting solution.
NaOH(aq) + HCl(aq) -> H2O(l) + NaCl(aq)
What is the metal, M?
Li
If a sample has an absorbance of 1.23 when it has a concentration of 5.83 mM in a 1.00 cm cuvette. What is the Molar Absorptivity?
Molar abs= 211 M^-1cm^-1
[BBG] (nM)Abs (a.u.)0.000.0385.000.07410.000.11115.000.149
📈 LINEST Output
📌 Other Variables
5.1 +- 0.5 nm
The calcium content in two different solutions were determined:
n=4 238 +- 8
n=5 255+- 10
Are the means significantly different at the 99% confidence level?
fcalc(1.56) < ftable std devs not sig different
tcalc(2.76)< ttable means not sig different
Consider the titration of 25.0 mL of 0.0255 M Cd(NO3)2 with 0.0120 M EDTA in a solution buffered at pH 9.00. (log Kf = 16.50 for the Cd2+-EDTA complex) a. Calculate pCd2+ at two of the volumes below.
At the equivalence point
At a volume halfway to the equivalence point
At a volume 11.0 mL after the equivalence point.
pCd= 8.04, 9.08, 15.39
A column has a length of 32.5 cm. For a given solute with a retention time of 342 seconds and a FWHM of 12.6 seconds, calculate the theoretical plate height for the setup.
H=8.0x10^-3 cm
A solution containing 3.46 mM X (analyte) and 1.72 mM S (standard) gave peak areas of 3473 and 10,222, respectively, in a chromatographic analysis. Then 1.00 mL of 8.47 mM S was added to 5.00 mL of unknown X and the mixture was diluted to 10.0 mL. This solution gave peak areas of 5428 and 4431 for X and S, respectively. a) Calculate the response factor for the analyte. b) Find the concentration of X in the original unknown solution.
F=0.1683
12.33 mM