Lecture 119/26/05 Seminar today

Step 3: Determine limiting reagent Can do this 2 ways: Compare stoichiometric ratio CO is limiting reagent

Step 3: Determine limiting reagent alternative approach Compare possible product from each reactant

Find moles of CH 3 OH From stoichiometric ratio with limiting reagent: 12.7 moles of CH 3 OH Find mass of CH 3 OH 407 g of CH 3 OH

How much H 2 left? Use stoichiometry to find H 2 used moles of H 2 needed for reaction 6.8 moles left 14 g left

To get mass of PCl 3 Use stoichiometric factor to get moles Convert moles to mass

4 flasks Baking Soda (NaHCO 3 ) Acetic Acid (CH 3 COOH) moles moles0.050 moles moles moles CH 3 COOH(aq) + NaHCO 3 (s)  NaCH 3 COO (aq) + H 2 O(l) + CO 2 (g) What is the relative order of balloon sizes? (a) 1=2=3=4(b) 4>3>2>1(c) 4>3=2>1(d) 4=3>2=1

Quantitative Analysis 1. Unknown amount of substance reacted with known amount of a second substance 2. Material of unknown composition converted to substances of known composition

2.367 g of a TiO 2 – containing sample evolves g of O 2. What is the mass percent of TiO 2 in the sample 3TiO 2 (s) + 4BrF 3 (l)  3O 2 (g) + 2Br 2 (l) + 3TiF 4 (s) mole TiO mole O g O g TiO 2

Burn g of a hydrocarbon, C x H y produce g of CO 2 and g of H 2 O What is the empirical formula of C x H y ? Empirical formula from combustion

CxHy + some O 2  g CO g H 2 O all C in CO 2 is from C x H y all H in H 2 O is from C x H y

1. 1. Calculate amount of C in CO x mol CO 2 --> 8.61 x mol C Calculate amount of H in H 2 O x mol H 2 O -- >1.149 x mol H

Find ratio of mol H/mol C to find values of x and y in C x H y x mol H/ 8.61 x mol C = 1.33 mol H / 1.00 mol C = 4 mol H / 3 mol C Empirical formula = C 3 H 4