Vocabulary
What is Le Chatelier's Principle?
A system will try to return to equilibrium if disturbed.
Calculate the ionic strength of a solution containing 0.3 M KCl and 0.2 M K2SO4.
0.9 M
Consider a mixture of the two solids, BaCl2∙2H2O and KCl. When the mixture is heated to 160 degrees C for 1 hour, the water of crystallization is driven off:
BaCl2∙2H2O(s) → BaCl2(s) + 2H2O(g)
A sample originally weighing 1.7839 g weighed 1.5623 g after heating. Calculate wt% Ba, K, and Cl in the original sample.
Ba 47.35%, K 8.279%, Cl 31.95%
What is the mobile phase?
The solvent moving through the column in chromatography. May be either a liquid or a gas.
If more oxygen is added to a methane combustion reaction, will the equilibrium shift towards the reactants, products, or neither?
Products
What is a systematic or method error?
A repeatable error made by making the same mistakes in measurement.
Find the molar absorptivity of a 0.0025 M KMnO4 solution whose absorbance is 4.53 when tested at 435 nm in a 1.00 cm cell.
1812 M-1cm-1
A solution of NaOH was standardized by titration of a known quantity of the primary standard, potassium hydrogen phthalate. Its concentration was determined to be 0.154 M. The NaOH was then used to standardize H2SO4.
H2SO4 + 2 NaOH → Na2SO4 + 2H2O
Titration of 50.00 mL of H2SO4 required 38.14 mL of NaOH solution. Calculate the concentration of H2SO4.
0.118 M H2SO4
What type of interference can be corrected by running a blank?
Background absorption
A data point that should be excluded from the data set; determined through Grubbs test.
Outlier
What type of titration measures the titrant by mass (not volume)?
Gravimetric titration.
Calculate spooled for the following data sets:
A: 24.57, 24.34, 26.57, 25.92, 25.77; B: 34.32, 32.84, 24.39, 30.84, 26.97.
0.06
What is the molarity of NaOH if 40.00 mL NaOH was used to titrate 0.5241 g sulfamic acid?
+H3NSO3- + OH- -> H2NSO3- + H2O
0.1349 M NaOH
What type of chromatography uses high pressure to force eluent through a closed column packed with micrometer-size particles?
High-pressure liquid chromatography (HPLC)
Something that can be added to a solution to prevent some impurities from reacting with the precipitant.
Masking agent
What is a buffer, and how is it formed?
A solution that resists changes in pH when small amounts of acid or base are added; adding a small amount of strong acid or base to a weak base or acid or by mixing a weak acid/base with a salt that contains the respective conjugate base/acid.
Calculate the pH of a solution that was made by adding 5 mL 0.106 M NaOH to 25 mL 0.102 M CH3COOH?
4.18
100.00 mL of 0.256 N K2Cr2O7 is titrated with 15.46 mL of 0.6781 N Fe3+. Find the potential at the cathode. Assume the total solution volume after additions is 235 mL and hydronium concentration is 1.0 x 10-3 M.
1.76 V
What instrumentation is involved for atomic absorption spectroscopy?
Source, sample, wavelength selector, detector, read out.
Ksp = 5.0 x 10-9
1.00 x 10-8
What two properties does the extended Debye-Huckel equation relate, and what are definitions for each of these properties?
Activity coefficients and ionic strength; the activity coefficient is the ratio of the chemical activity of a substance to its molar concentration and is used to calculate the activity of a solution, which is a measure of the effective concentration of a species in a mixture; the ionic strength is a measure of the total concentration of ions in a given solution.
Write a charge balance for a solution of H2SO4 in water if the H2SO4 ionizes to HSO4- and SO42-.
[H+]=[OH-]+[HSO4-]+2[SO42-]
Ni2+ can be analyzed by a back titration with standard Zn2+ at pH 5.5 and xylenol orange indicator. A solution containing 25.00 mL of Ni2+ in dilute HCl was treated with 25.00 mL of 0.05283 M Na2EDTA. The solution was neutralized with NaOH, and the pH was adjusted to 5.5 with acetate buffer. The solution turned yellow when a few drops of indicator were added. Titration with 0.02299 M Zn2+ required 17.61 mL of Zn2+ to reach the red end point. What was the molarity of Ni2+ in the unknown?
0.03664 M Ni2+
Name the types of interference that occur in atomic spectroscopy.
Calculate E0 and K for the following reaction:
2F2 (g) + H2O <--> F2O(g) + H+ + 2F-
E0 = 0.722 V
K = 7 x 1048