Chemistry Exam Review and Practice Problems
Prepare for your upcoming chemistry exam with a comprehensive review covering scientific notation, molecular weights, stoichiometry, limiting yield problems, and more. Practice balancing reactions, converting between units, and determining empirical formulas to boost your understanding of key concepts.
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EXAM 3 Review summary powerpoints 25-38 mini quizzes 16-23 homework 8,9 exercises 4, 5,6,7 EXAM SCHEDULED FOR MONDAY 5 MAY (75 points total) 3.1. Scientific notation and prefixes (8 pts) Express 123,456 in scientific notation: _______________ Express 5.43*10-3 in decimal notation: ___________________ Re-write the quantities below in terms of their most reasonable, prefixed equivalents. 10,000 m = _____________________ 0.0000020 s= ____________________ 3.2 Molecular Weight (MW) (3 pts) _ Calculate the molecular weights (g/mol) for the compounds below to the nearest gram/mol C4H100 __________________________ g/mol 3.3. Basic Weight-Mole-molecule count conversions(Show workorno credit !!) 5 pts each/20 pts total Note: Avogodro s number = 6.022 *1023= the `chemist s dozen How many grams of H2O (MW=18) are in 0.16666 moles of H2O ? How many molecules of Na3P (MW=100) are in 1.6606*10-22 grams of Na3P?____ molecules Na3P How many moles of KF (MW=58)are in 232 grams of KF?_____ moles KF ____g H2O 3.4 % Composition Problems (9 pts/ 3 pts each) A sample of compound composed of C,H and O contains 0.720 g C, 0.120 g H and 0.640 g O, determine the empiric formula of the compound: Element C H O Weight, g AW g/mol 12 1 16 2 grams of C are burned in air to make a 7.333 g sample of COx . Given atomic wts for C=12 and O=16, what is the formula for COx
EXAM 3 Review summary (continued) 3.5. Reaction balancing 6 pts (2 pts per equation) Ex. Balance this reaction: ____C8H18 + ___O2-------- _____CO2 + ____H2O 3.6 Chemical Stoichiometry (15 Pts) [Show work for each problem or no credit] 3 problems (avogodro s # =6.022*1023) Example: MW(g/mol) Given the following balanced equation: C3H8 + 5O2 -------- 44 32 44 18 g/mol 3CO2 + 4H2O Compute the number of grams of H2O created by burning 0.06944 moles O2 ? ________g H2O Compute the number of molecules of H2O created by burning 7.30897 g C3H8_______________ MOLECULES Compute the number of moles of CO2 created by consuming 29.333 g C3H8? ______mol C3H8 3.7. Limiting Yield Problems 9 pts (2 problems) 2Al +6HCl 2AlCl3 + 3H2 Ex. MW(g/mol 27 36 133 2 3 mol of Al and 12 moles of HCl are reacted. How many grams of H2 can form? 3.8. T/F (5 pts) The mole concept and dozen concept are essentially the same. Stoichiometry and Souffle recipe calculations are essentially the same. There s nothing special about Avagodro s number. T T T F F F
IN-CLASS WORK ON LIMITING YIELD PROBLEMS EXERCISE 7
Organic structures and naming (see Organic naming ppt)
