Question

2，3，4，5

CHEM 1113: Recitation Activity - Week 3 Stoichiometry Learning Goals • Determine the limiting reactant and excess reactant for chemical reactions on the molecule scale. • Determine the amount of product that can be formed based on the starting amounts of a chemical system. • Calculate the amounts of reactants, products, or leftovers for chemical reaction problems with limiting and excess reactants in both moles and grams. Part I: Quantitative Aspects of Chemical Formulas 1. What is the mass percent of hydrogen in H2O? 2. How many fluorine atoms are there in 19 g of difluoromethane, CH2F2? 3. Two moles of a gaseous elemental halogen weighs 141.8 g. What is the gas? 4. A sample of 0.370 mol of a metal oxide (M20.) weighs 55.4 g. What is the possible identity of metal M? 5. One of the several oxides of tin found in the Earth's crust is 78.77% by mass tin. What is its empirical formula and name?

Answer 1

* 2 * MM X 1004 - Mn = matar mass of hydrogen - MHD e molar mass of Hype * 2 * 1.0079 g/mol x 1004 18.015 - 11-19 / H Given mass of Clef = Total no. of Chafa molecules Molar mass of Chifz Avagadro number. 19 g Total no. of Chafa molecules 52.0g 6.022 x 1023 Tural no. of chlaf molecules 19 6.022 x 1025 52.0 : l.2 x 1023 Each molecule have a fluorine atom, herpes 2 * 2.2 x 1023 4,4 *01023 F atom Halogens are typically diatomic, so two mole of gas will have 4 moles of atoms. 3. و أنهم رواه * ليعه مها 08 آبا1 : ملوک ک3 1 halogen atom . total atom 4 for chlorine - Gas is a 1 Mole of M2O3 = Given mass of M203 I Let malar mass Molar mass of Mels .M.lar mass of 0.370 55.4 M2O3 + 2x +48 2x +48 0.370| 2 x +48 ) ; 55,4 0.74 x + 17-76 s 55.4 > 6.74 a s 55.4 - 17.76 => 0.74 ms 37-64 2 537-6470-74-50.86

50.86 is molar mass of antimony. (Sb). Il Assume 100% of sample as juo gram of sample Mass Moles | Sn 78.77 78 71/118.71 : 0.6636 o 21:23 21.23/16 S 1, 3269 Dinner Dividing the number of moles of each element with the smallest value, we will have the emperical formula Ratio moles 0.6636 0.6636/0-6636 51 1:3269 1:3269 / 0.663632 formula is Sn O