1. Lecture 119/26/05 Seminar today

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

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

4. 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

5. How much H 2 left? Use stoichiometry to find H 2 used. 25.4 moles of H 2 needed for reaction 6.8 moles left 14 g left

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

7. 4 flasks Baking Soda (NaHCO 3 ) Acetic Acid (CH 3 COOH) 10.050 moles 20.100 moles0.050 moles 30.100 moles 4 0.200 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

8. 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

9. 2.367 g of a TiO 2 – containing sample evolves 0.143 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) 0..0045 mole TiO 2.0045 mole O 2 0.143 g O 2 0.357 g TiO 2

10. Burn 0.115 g of a hydrocarbon, C x H y produce 0.379 g of CO 2 and 0.1035 g of H 2 O What is the empirical formula of C x H y ? Empirical formula from combustion

11. CxHy + some O 2  0.379 g CO 2 + 0.1035 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

12. 1. 1. Calculate amount of C in CO 2 8.61 x 10 -3 mol CO 2 --> 8.61 x 10 -3 mol C 2. 2. Calculate amount of H in H 2 O 5.744 x 10 -3 mol H 2 O -- >1.149 x 10 -2 mol H

13. Find ratio of mol H/mol C to find values of x and y in C x H y 1.149 x 10 -2 mol H/ 8.61 x 10 -3 mol C = 1.33 mol H / 1.00 mol C = 4 mol H / 3 mol C Empirical formula = C 3 H 4