Chem 111 1st Edition Lecture 7 Review Problems:Finding % Composition from a formula1. Find the molar mass using periodic table2. Calculate the % weight for each elementExample: Calculate MW of C2H6O(2x12.011u)(6x1.0079u)+(1x15.9999u)46.068 u%C=(2x12.011u/46.068)x100%=52.145%%H=(6x1.0079u/46.068)x100%=13.127%%O=(1x15.999u/46.068)x100%=34.729%Calculate Empirical Formula given percent compositionGiven: N=30.45%O=69.55%1. Assume weight of 100gN=60.45gO=69.55g2. Convert from Grams to Moles30.45gN x (1mol/14.007g)=2.17 mol69.55gO x (1 mol/15.999g)=4.35 molN2.17O4.353. Find the smallest ratio divide by smallest numberN: 2.17/2.17=1O: 4.35/2.17=2Anwer : N O2ou burn 8 lbs of butane (C4H10) . How many pounds of CO2 are produced. 1. Write a balanced equationC4H10+O2−→ C O2+H2OC4H10+6.5 O2−→ 4 C O2+5 H2O2. Convert pounds to moles8lbs x (453.9 g/lb) x (mol/58.123g)=62.47 moles butane3. Determine the # of moles CO2 producedC4H10+6.5 O2−−→ 4 C O2+5 H2O62.47 moles C4H10x(44.01 gmol)=249.9 moles C O2These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.4. Convert back to pounds62.47 moles C4H10x(44.01 gmol)x(lb453.9 g)=24.23 lb of C O2If 400.34g of CaCO3 decomposes, how many grams of CO2 are produced?1. Write a balanced equationCaC O3−→CaO +C O2100.086g/mol 56.077g/mol 44.009g/mol2. Convert pounds to moles400.34 g x (1mol/100.086g)=4.0000moles3. Multiply by appropriate stoichiometric factor4 moles of CaCO3 leads to 4 moles of CO24. Convert back to grams4.1 moles Co2 x 44.009 g/mol=176.04gIf you have 100g each of P, I2, and H2O, which is the limiting reagent?2 P+3 I2+6 H2O−→ 2 HPO(OH)2+6 HI1. Balance Equation (already done)2. Convert to moles# of moles of P: 100g/31 g mole=3.23 moles P2.23 moles P x 6 moles HI/ 2 moles P=9.69 moles HI# of moles of I2: 100g/254 g mole=.394 moles I26 moles HI/3 moles I2=.788 moles HI# moles H2O=100g/18 g mole=5.56 moles H2O6 moles HI/6 moles H2O=5.56 moles of HIHI is the limiting reactant!Acid Base ReactionsHN O3(aq)+NaOH(aq)−−−→ NaN O3(aq)+HOHQuestion: What is the net ionic equation?NO3- and Na+ aren’t doing anything-they started in solution (Na+(aq)) and they ended In solution (Na+(aq))Answer: −¿(aq)−−−→ H2O+¿(aq)+O