How do you calculate moles for 2g of sodium hydroxide in 20 ml?

To calculate the moles of sodium hydroxide (NaOH) in 2 grams, use the formula: moles = mass (g) / molar mass (g/mol). The molar mass of NaOH is approximately 40 g/mol. Therefore, the number of moles is 2 g / 40 g/mol = 0.05 moles. The volume of 20 ml does not affect the calculation of moles but can be used for further calculations, such as molarity.