Quick answer: Molarity is moles of solute per litre of solution, and dilution follows M₁V₁ = M₂V₂. This AP Chemistry test on Beer-Lambert law has 8 questions worth 20 marks, to do in 45 minutes: molarity, dilution and chromatography. The mark scheme is on a separate page; free printable PDF.
This AP Chemistry test on Beer-Lambert law test works like a real class test. The mark scheme is on a separate page, so revise with the lesson first.
This test lasts 45 minutes and is worth 20 points. Show your working, quote final answers with units and sensible significant figures, and refer to the relevant relationships. Calculators are allowed.
Level: AP Chemistry · Curriculum: AP Chem Unit 3
Beer-Lambert law test: the test questions
Question 1 Molarity (3 marks)
Calculate the molarity of a solution made by dissolving 4.00 g of NaOH (40.00 g/mol) in water and making the volume 200.0 mL.Question 2 Dilution (3 marks)
What volume of 6.00 M HCl is needed to prepare 250.0 mL of 1.20 M HCl?Question 3 Chromatography (2 marks)
On a TLC plate a spot moved 3.2 cm while the solvent front moved 8.0 cm. Calculate Rf and state what it shows.Question 4 Beer-Lambert calculation (3 marks)
A solution of concentration 2.5 × 10⁻⁵ mol/L gives A = 0.375 in a 1.00 cm cuvette. Calculate the molar absorptivity.Question 5 Percentage transmittance (2 marks)
A solution has A = 0.699. Calculate the percentage of light transmitted.Question 6 Calibration line (3 marks)
- An unknown sample has A = 0.300. Use the graph to find its concentration. (1 mark)
- State what the straight line shows about the relationship between A and c. (1 mark)
- Explain why you should not use the line to find c for A = 2.0. (1 mark)
Question 7 Separation methods (2 marks)
Name the method that would separate each pair: (i) iodine dissolved in ethanol, getting back the ethanol; (ii) the pigments of a leaf extract.Question 8 Choosing the wavelength (2 marks)
Explain why a spectrophotometric analysis uses the wavelength of maximum absorbance.
