Required practical 10: prepare an organic solid and test its purity.

In the subtopic A-level required practical activities, this AQA A-Level Chemistry 7405 learning objective focuses on required practical 10: prepare an organic solid and test its purity. It belongs to A-level practical endorsement and required practical activities, so revision should stay anchored to this exact subtopic rather than drifting into a generic GCSE-level chemistry summary. Approved keywords to use include required practical. Purity testing. means the evaluation of an organic solid to determine its composition and the presence of impurities, often using methods such as melting point determination Avoid the mistake of students often forget to convert the mass of the organic solid to moles before calculating purity, leading to incorrect results; instead, to calculate purity, use the formula: purity (%) = (mass of pure substance / total mass) x 100. First, convert the mass of the organic solid to moles using the formula: moles = mass / Mr. Then, substitute the values into the purity formula. For example, if you have 5 g of a substance with an Mr of 100 g/mol, first calculate moles: 5 g / 100 g/mol = 0.05 mol. If the mass of pure substance is 4 g, then purity = (4 g / 5 g) x 100 = 80%. Thus, the purity of the organic solid is 80% For exam answers, always ensure that you accurately measure the mass of your organic solid before testing its purity