Worksheet 3.5: Mole Reaction Equations REMEMBER to start by balancing the equations! 1 a) C 2H 6 10. moles + O2 à b) CO2 + H 2O 0.20 moles Parts a) and b) are completely separate (unrelated) scenarios 2 a) Mg3N2 b) 36 moles + H 2O à Mg(OH)2 + NH3 0.48 moles For each of the following word problems, you should SHOW your CHECK of the LAW of CONSERVATION of MASS. 3- A reaction between tin and oxygen produced 68.6 g of SnO2 (the only product). How many grams of tin and oxygen were involved? 4- A reaction between phosphorus and hydrogen yielded 10.5 g of phosphorus trihydride. How many grams of phosphorus and hydrogen were needed for the reaction? 5- Zinc and sulphur combine chemically to produce ZnS. How many grams of the sulphide are produced if 25.9 g of zinc reacts with sulphur? How many grams of sulphur were needed? 6- In the thermite process, aluminum reacts with Fe3O4 to give Al2O3 and iron. We will learn, in Chemistry 11, that compounds with unpredictable charges, such as in the Fe3O4, are completely possible! If 40.2 g of iron are produced, find the masses of the other chemicals involved. Wkst 3.5: Mole Reaction Equations ANSWER KEY 1a) b) 2C2H6 10. moles 0.10 moles + 7O2 35 moles 0.35 moles à 2a) b) Mg3N2 0.24 moles 36 moles + 6H2O à 1.4 moles 220 mol 3Mg(OH)2 0.72 moles 110 moles 4CO2 + 20. moles 0.20 moles 6H2O 30. moles 0.30 moles + 2NH3 0.48 moles 72 moles 3. ? Moles of SnO2 = (1 mole / 151 g) (68.6 g) = 0.454 moles SnO2 Sn + O2 à SnO2 0.454 moles 0.454 moles 0.454 moles ?gO2 =(32.0g/mole)(0.454moles)=14.5g O2 ?gSn=(119g/mole)(0.454moles)=54.0g Sn Check: Σ mass of reactants = Σ mass of products 54.0g+14.5g=68.6g 68.5g=68.6g Good! 4. The reaction needed 9.59 g of phosphorus and 0.937 g of hydrogen. 5. 12.7 g of sulphur were required to react with the zinc to produce 38.6 g of zinc sulphide. 6. Mass of Al=17.3g Mass of Fe3O4 = 55.4 g Mass of Al2O3 = 32.6 g