CHEM 121 Lecture Notes - Lecture 5: Aqueous Solution, Sodium Chloride, Electronegativity
19 Jun 2015
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Chem 121 - lecture 5 - chemical reactions and stoichiometry. Values in formula must be whole numbers. C1. 75h2. 5o values not close enough to be rounded. From % composition, determine mass of each in 100g sample of compound. Determine # moles of each in 100g sample. Chemical formula = cxhyoz, where x, y, z are whole ratios of moles. Dibutyl succinate is an insect repellent used against household ants and roaches. Its composition is 62. 58% c, 9. 63% h and 27. 79% o. C5. 21h9. 56o1. 74 (not whole numbers, divide by 1. 74) -> c2. 99h5. 52o1 (still not. Calculation of a molecular formula whole numbers, so multiple by 2) -> c6h11o2. A compound has an empirical formula of ch2o; its molar mass is 180. 01g/mol. Empirical formula mass = 12. 01+2(1. 008)+15. 99 = 30. 016g/mol. Balanced equation ; 2kclo3 (s) -> 2kcl (s)+3o2 (g) Note: coefficient refers to relative number of moles (must convert to moles) 50. 0go2 x 1 molo2/31. 998go2 = 1. 563 molo2. Use molar ratios in a balanced equation.
