Gizmos Student Exploration Stoichiometry Answers Key

Gizmos Student Exploration Stoichiometry Answers Key. Avogadro’s number, balanced equation, cancel, coefficient, conversion factor, dimensional analysis, molar mass, mole, molecular mass, stoichiometry Activity A: Moles Get the Gizmo ready: ● Check that the equation is still: Fe2O3 + 3CO 2Fe + 3CO2 ● If not, click New equation until it reappears. Question: How do scientists find the molecular mass and molar mass of a substance? 1. Calculate: The molecular mass of a molecule is the sum of the masses of each atom in the molecule. The unit of molecular mass is the universal mass unit (u). Iron’s atomic mass is 55.85 u, carbon’s mass is 12.01 u, and oxygen’s mass is 16.00 u. A. Calculate the molecular mass of carbon monoxide (CO) by adding the atomic mass of carbon and the atomic mass of oxygen: ______28.01g____________________ B. Calculate the molecular mass of carbon dioxide (CO2 ): ____44.01g_____________ C. Calculate the molecular mass of iron (III) oxide (Fe2O3 ): ______159.7 g__________ 2. Infer: A mole of a substance has a mass in grams that is equal to the molecular mass. For example, a carbon atom has a mass of 12.01 u. A mole of carbon has a mass of 12.01 g. Based on their molecular masses, list the molar mass of each substance: Fe2O3 ___159.7 g___ CO __28.01g____ Fe __55.85g___ CO2 __44.01g___ Check your answers on the Gizmo by inspecting the middle row of tiles on the right side of the Gizmo. These tiles show the units “1 mol” on top and “g” below. 3. Practice: Hydrogen has an atomic mass of 1.01 u. What is the molar mass of these substances? H2O __18.02g____ CH4 __16.05g___ H2CO3 ___62.03g_ C6H12O6 __180.18g__ Activity B: Canceling units Get the Gizmo ready: ● Check that the equation is still: Fe2O3 + 3CO 2Fe + 3CO2 Introduction: While solving problems in stoichiometry, it is useful to pay attention to the units of the answer. The process of comparing units is called dimensional analysis. A common technique involves using conversion factors to convert from one unit to another. Units that appear in the numerator and denominator of a fraction can be canceled out. For example, converting 2 moles of carbon monoxide to grams involves multiplying by a conversion factor: 2 mol CO • 28.01 g CO = 56.02 g CO