The concentration of sodium ions in a water sample was measured as 4.57 × 10⁻³ mol dm⁻³. What is this concentration expressed as parts per million?  

0.585 g of hydrated magnesium nitrate, CuSO₄.5H₂O were dissolved in 100.0 cm³ of water. 10.0 cm³ of this solution were made up with water to 50.0 cm³. Calculate the concentration of Cu²⁺ ions in the resulting solution.

2, 3−dimethylbutane has a retention time of 2.2 minutes and hexane has a retention time of 3.5 minutes in a particular gas chromatogram. Determine the relative retention of 2,3−dimethylbutane to hexane.

The molar absorption coefficient for solutions of a compound is 235 mol^–1 dm³ cm^–1 at a wavelength of 600 nm. Determine the fraction of light of this wavelength transmitted through a sample of a solution of concentration 2.00 × 10⁻³ mol dm^–3 in a cuvette with a path length of 1.00 cm.

In order to test the suitability of a solvent for extraction purposes, 0.60 g of solute with molar mass 97.9 g/mol was dissolved in 10.00 mL of water. 10.00 mL of cyclohexane was added, and the system allowed to equilibrate. After extraction 0.45 g of solute is recovered in the organic phase. What is the partition coefficient between water and cyclohexane (expressed as a log K)?

A Beer-Lambert analysis is used to determine the extinction coefficient for a compound B in water, and it is found to be 12.5 m² mol⁻¹ at 520 nm. A solution of compound B is analysed by UV/visible spectroscopy and the absorbance at 520 nm is recorded as 0.45 in a 1 cm cell. What is the concentration of this solution?

The concentration of chloride ions in a water sample is 145 ppm. Calculate this concentration in mol dm⁻³.

The pF of a sample is recorded as 2.2. What is the fluoride ion concentration?

A Beer-Lambert analysis is used to determine the extinction coefficient for a compound in water, and it is found to be 2230 dm³ mol⁻¹ cm⁻¹ at 490 nm. A solution of the compound is analysed by UV/visible spectroscopy and the absorbance at 490 nm is recorded as 0.29 in an 0.5 cm cell. What is the concentration of this solution?

In the analysis of the products of a synthesis using thin layer chromatography, spots were observed to have risen distances of 24, 32, and 43 mm up the silica-coated plate, with the solvent front rising to 57 mm. In an analysis of one of the starting materials using the same solvent and type of plate, the spot for the pure compound was observed to rise through 38 mm with the solvent front rising through 67 mm. Which of the spots from the product mixture corresponds to the starting material?