# Chapter 4 Skills Balance Equations for simple chemical

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Chapter 4 Skills • Balance Equations for simple chemical reactions • Perform stoichiometry calculations using balanced chemical equations – Mass relationships – Amounts tables • Understand the impact of a limiting reactant on a chemical reaction – Amounts tables • Calculate theoretical and percent yields of a chemical reaction • Stoichiometric uses – Analysis of mixtures – Determination of empirical or molecular formulas • http: \now. brookscole. comkotz 6 e 3/12/2021 Kull Chem 105 Chapter 2 1

Cation Anion Name Formula ammonium bromide Li+ Li. Cl. O 4 Fe 2+ Cllead(II) fluoride Al 3+ Al. PO 4 lithium bromide Ba 2+ Ba. S NO 3 - barium nitrate Ba(NO 3)2 Al 2(CO 3)3 Al 3+ O 2 - aluminum oxide Al 2 O 3 Fe 3+ O 2 - iron(III) oxide Fe 2 O 3 --- --- --- 3/12/2021 boron triiodide S 2 Cl 2 tetraphosphorus trisulfide 2

Cation Anion Name Formula NH 4+ Br- Ammonium bromide NH 4 Br Li+ Cl. O 4 - Lithium perchlorate Li. Cl. O 4 Fe 2+ Cl- iron(II) chloride Fe. Cl 2 Pb 2+ F- Lead(II) fluoride Pb. F 2 Al 3+ PO 43 - aluminum phosphate Al. PO 4 Li+ Br- Lithium bromide Li. Br Ba 2+ S 2 - Barium sulfide Ba. S Ba 2+ NO 3 - Barium nitrate Ba(NO 3)2 Al 3+ (CO 3)2 - Aluminum carbonate Al 2(CO 3)3 Al 3+ O 2 - Aluminum oxide Al 2 O 3 Fe 3+ O 2 - Iron(III) oxide Fe 2 O 3 --- boron triiodide BI 3 --- disulfur dichloride S 2 Cl 2 --- tetraphosphorus trisulfide P 4 S 3 3/12/2021 3

Understand the impact of a limiting reactant on a chemical reaction 20. ■ Ammonia gas can be prepared by the reaction of a metal oxide such as calcium oxide with ammonium chloride. Ca. O(s) + 2 NH 4 Cl(s) 2 NH 3(g) + H 2 O(g) +Ca. Cl 2(s) If 112 g of Ca. O and 224 g of NH 4 Cl are mixed, what mass of NH 3 can be produced? 3/12/2021 4

Answers • 4. 20 112 g Ca. O · = 2. 00 mol Ca. O 224 g NH 4 Cl · = 4. 19 mol NH 4 Cl Ca. O has fewer moles and is the limiting reactant 112 g Ca. O · · · = 68. 0 g NH 3 Equation Ca. O(s) + 2 NH 4 Cl(s) 2 NH 3(g) + H 2 O(g) + Ca. Cl 2(s) Initial (mol) 2. 00 4. 19 0 0 0 Change (mol) – 2. 00 – 4. 00 +2. 00 Amt after rxn(mol) 0 0. 19 4. 00 2. 00 3/12/2021 5

Calculate theoretical and percent yields of a chemical reaction 30. A reaction studied by Wächtershäuser and Huber (see “Black Smokers and the Origins of Life”) is 2 CH 3 SH + CO CH 3 COSCH 3 + H 2 S If you begin with 10. 0 g of CH 3 SH, and excess CO, (a) What is theoretical yield of CH 3 COSCH ? (b) If 8. 65 g of CH 3 COSCH 3 is isolated, what is its percent yield? 3/12/2021 6

Answers • 4. 30 (a) 10. 0 g CH 3 SH · · · = 9. 37 g CH 3 COSCH 3 (b) · 100% = 92. 3% yield 3/12/2021 7