Analytical Chemistry

Use this for “0.4000 ± 0.0003 g of KCl (74.55 g/mol) is made up to 0.5000 ± 0.0002 L. Give the molarity with its uncertainty.”

Use this for “Four titrations take 24.18, 24.21, 24.22 and 24.39 mL. Qcrit is 0.829 for four readings at 95%. May 24.39 mL be rejected?”

Use this for “A standard certified at 5.00 mg/L lead reads 5.21 mg/L on average over 6 runs, s = 0.18 mg/L. Is the method biased at 95%?”

Use this for “An antacid tablet dissolves in 40.00 mL of 0.2000 M HCl, and the excess acid takes 12.35 mL of 0.1500 M NaOH. How many mg of CaCO₃ did it hold?”

Use this for “A 75 mL tap-water sample takes 13.99 mL of 0.01000 M EDTA at pH 10. Report the hardness in mg/L as CaCO₃.”

Use this for “25.00 mL of 0.0800 M maleic acid (pKₐ₁ = 1.92, pKₐ₂ = 6.27) is titrated with 0.1000 M NaOH. Find both equivalence volumes and the pH at the first.”

Use this for “Which indicator suits the titration of propanoic acid with NaOH, whose equivalence point is at pH 8.8?”

Use this for “Iron standards give the line A = 0.0820c + 0.0030 (c in mg/L). A sample diluted 5 times reads A = 0.415. How much iron was in the sample?”

Use this for “Co²⁺ and Ni²⁺ both absorb at 510 nm and 395 nm. From their ε at each wavelength and the mixture’s two absorbances in a 1 cm cell, find both concentrations.”

Use this for “A 5.00 mL water sample gives a lead signal of 0.150. With 0.50 mL of 50 mg/L lead standard added, both made up to 25.00 mL, it reads 0.270. Find the lead concentration.”

Use this for “A column has A = 0.050 cm, B = 0.40 cm²/s and C = 0.010 s. Find the flow speed that gives the smallest plate height, and that height.”

Use this for “Two compounds have α = 1.08 and k₂ = 3.2 on a column. How many plates give a resolution of 1.5?”

Use this for “Which technique would you use to measure the chloride and bromide ions in a well-water sample?”

Use this for “A pH electrode reads +0.1650 V in a pH 4.01 buffer and −0.0120 V in a pH 7.00 buffer. A sample reads +0.0800 V. Find the slope, its percent of the ideal and the sample’s pH.”

Use this for “A 0.9000 g magnesite sample weighs 0.5172 g after heating to constant mass, the loss being CO₂ (44.01 g/mol). What percent is MgCO₃ (84.31 g/mol)?”

Use this for “A 0.6000 g mixture of NaCl and KCl, dissolved and treated with excess AgNO₃, gives 1.3250 g of AgCl. What percent of the mixture is NaCl?”

Use this for “A river sample reads 3.6 ppb lead. A spike that adds 5 ppb is put into a second portion, which then reads 8.3 ppb. What is the recovery?”

Use this for “Ten blank readings have a standard deviation of 0.0035, and the calibration slope is 0.125 per ppm. Find the detection and quantitation limits.”

Use this for “NADH (ε = 6220 L/(mol·cm)) falls by 0.120 absorbance per minute in a 1 cm cell holding 3.00 mL, 0.050 mL of it the sample. Find the activity in U/mL.”