Download presentation

Presentation is loading. Please wait.

Published byShemar Symmonds Modified over 2 years ago

3
Tuesday, Feb. 25 th : “A” Day Wednesday, Feb. 26 th : “B” Day (1:05 out) Agenda Homework Questions/Collect Finish Section 13.2: “Concentration and Molarity” Solution dilution equation, using molarity in stoichiometric calculations Homework: Practice Pg. 467: #1-3 Section 13.2 review, pg. 467: #1-14 Concept Review: “Concentration and Molarity”

4
Homework Practice pg. 461: #2, 3, 5, 6 Practice pg. 465: #1-7

5
Solution Dilution Often, solutions such as acids are sold in very concentrated form, such as 12 M HCl. However, in the lab, we rarely use such concentrated acids. How do scientists dilute these very concentrated solutions to get the concentration or molarity that is needed for their experiment?

6
Solution Dilution Equation M = mol L M x L = mol OR Solution Dilution M 1 V 1 =M 2 V 2

7
Solution Dilution Demo The concentration of the CuSO 4 solution I made last time was supposed to be 0.05 M, NOT 0.50 M. Do I have to throw away the solution I made last time, or can I somehow fix it? Use the solution dilution equation: M 1 V 1 = M 2 V 2 M 1 : the original concentration I made (0.50 M) V 1 : what volume of that solution will I need (?) M 2 : the new concentration I’m trying to make (0.05 M) V 2 : the volume of the new concentration I’m making: 250 mL (0.50 M) V 1 = (0.05 M) (250 mL) V 1 = 25 mL

8
How many liters of 0.155 M Ni(NO 3 ) 2 can be made from 75.0 mL of 12.0 M Ni(NO 3 ) 2 ? Use the solution dilution equation: M 1 V 1 = M 2 V 2 M 1 : 12.0 M V 1 : 75.0 mL M 2 : 0.155 M V 2 : ? (12.0 M) (75.0 mL) = (0.155 M) (V 2 ) V 2 = 5,806 mL → 5.81 L Dilution Example #1

9
Dilution Example #2 What volume of 19 M NaOH must be used to prepare 1.0 L of a 0.15 M NaOH solution ? Use the solution dilution equation: M 1 V 1 = M 2 V 2 M 1 : 19 M V 1 : ? M 2 : 0.15 M V 2 : 1.0 L (19 M) V 1 = (0.15 M) (1.0 L) V 1 =.00789 L → 7.9 mL

10
Using Molarity in Stoichiometric Calculations There are many instances in which solutions of known molarity are used in chemical reactions in the laboratory. Instead of starting with a known mass of reactant or with a desired mass of product, the process involves a solution of known molarity. The substances are measured out by volume, instead of being weighed on a balance.

11
Sample Problem C, Pg. 466 What volume (in mL) of a 0.500 M solution of copper (II) sulfate, CuSO 4, is needed to react with an excess of aluminum to provide 11.0 g of copper? 3 CuSO 4 (aq) + 2 Al (s) 3 Cu (s) + Al 2 (SO 4 ) 3 (aq) First, use molar mass to change gram Cu → moles Cu: 11.0 g Cu X 1 mole Cu = 0.173 mole Cu 63.5 g Cu Next, use mole ratio to change mole Cu → mole CuSO 4 : 0.173 mole Cu X 3 mol CuSO 4 = 0.173 mole CuSO 4 3 mole Cu Last, use molarity to find volume of solution and convert to mL: 0.173 mole CuSO 4 X 1 L CuSO 4 X 1,000 mL = 346 mL 0.500 mole CuSO 4 1 L CuSO 4

12
Additional Example A zinc bar is placed in 435 mL of a 0.770 M solution of CuCl 2. What mass of zinc would be replaced by copper if all of the copper ions were used up? Zn + CuCl 2 → Cu + ZnCl 2 First, convert to L and then use molarity to find moles of CuCl 2 : 435 mL CuCl 2 X 1 L X 0.770 mol CuCl 2 = 0.335 1,000 mL 1 L CuCl 2 mol CuCl 2 Next, use mole ratio to change mol CuCl 2 → mol Zn: 0.335 mol CuCl 2 X 1 mol Zn = 0.335 mol Zn 1 mol CuCl 2 Last, use molar mass mol Zn→ gram Zn: 0.335 mol Zn X 65.4 g Zn = 21.9 g Zn 1 mol Zn

13
Another Example What volume, in mL, of a 1.50 M HCl solution would be needed to react completely with 28.4 g of Na 2 CO 3 to produce water, CO 2, and NaCl? Na 2 CO 3 + 2 HCl H 2 O + CO 2 + 2 NaCl First, change grams Na 2 CO 3 → mole Na 2 CO 3 : 28.4 g Na 2 CO 3 X 1 mol Na 2 CO 3 = 0.268 mol Na 2 CO 3 106 g Na 2 CO 3 Next, use mole ratio to change mol Na 2 CO 3 →mol HCl: 0.268 mol Na2CO3 X 2 mol HCl = 0.536 mol HCl 1 mol Na 2 CO 3 Last, use molarity to find volume of solution and convert to mL: 0.536 mol HCl X 1 L HCl X 1,000 mL = 357 mL HCl 1.50 mol HCl 1 L

14
Homework Practice pg. 467: #1-3 Section 13.2 review, pg. 467: #1-14 Concept Review: “Concentration and Molarity” Next Time: Quiz over this section…

Similar presentations

OK

1 © 2006 Brooks/Cole - Thomson Quantitative Aspects of Reactions in Solution Sections 5.8-5.10.

1 © 2006 Brooks/Cole - Thomson Quantitative Aspects of Reactions in Solution Sections 5.8-5.10.

© 2018 SlidePlayer.com Inc.

All rights reserved.

Ads by Google

Ppt on carbon and its compound download Ppt on cross site scripting examples Ppt on asian continent outline Ppt on great monuments of india Ppt on different sectors of economy for class 10 Ppt on db2 introduction Ppt on turbo generator maintenance Ppt on game theory prisoner's dilemma Download ppt on civil disobedience movement Ppt on online hotel management system