Question

Experiment 17 Pre-lab Name 1. Define the following in your own words: Empirical Formula: Molecular Formula: Weigh by difference: 2. A sample of Calcium metal is added to a 38.500 g crucible and the combined weight is 38.750 g. The sample is then heated in the crucible to form calcium Oxide. After the crucible is completely cooled, the crucible and product weigh 38.850 9. a) what is the mass of the calcium in the crucible? b) what is the mass of the oxygen that reacted with the calcium? c) how many moles of calcium were in the crucible? d) how many moles of oxygen reacted with the calcium? e) what is the empirical formula of the product?

Answer 1

Empirical formula is defined as ratio of elements present in the compound, but not the actual numbers of atoms in the molecule
=> Empirical formula i It shows the ratio of elements present in the compound, but not the actual numbers of atoms in the molecule. It is also known as simplest formula because the subscripts are the smallest whole numbers that indicate the ratio of elements. Example Molecular formula of Glucose is G H 2 Op. Empirical formula of Glucose is CH, O. That means Glucose has 2 moles of Hydrogen for every mole of carbon and onggen. =) Molecular formula : . It is a chemical formula that indicates the kinds of atoms and the number of - each kind in a molecule of a compound > Molecular formula describes the exact number and type of atoms in a single molecule of a compound. Example: Hydrogen peroxide has moleculas (

formula H2O2 and empirical formula HO =) Weigh by Difference : Weighóng by difference is a way to weigh materials accurately. Weight of the material is the difference between the fwo weights of 5 the vial before and after transferring the material from the vial. - Weighing lay difference is very accurate because it can take away most errors made by the scale. mo