Download presentation

1
**II. Solution Concentration (p. 480 – 486)**

Ch. 16 – Solutions II. Solution Concentration (p. 480 – 486)

2
**A. Concentration The amount of solute in a solution**

Describing Concentration % by mass - medicated creams % by volume - rubbing alcohol ppm, ppb - water contaminants molarity - used by chemists molality - used by chemists

3
**substance being dissolved**

B. Percent Solutions Percent By Volume (%(v/v)) Concentration of a solution when both solute and solvent are liquids often expressed as percent by volume substance being dissolved total combined volume

4
B. Percent Solutions Find the percent by volume of ethanol (C2H6O) in a 250 mL solution containing 85 mL ethanol. Solute = 85 mL ethanol Solution = 250 mL 85 mL ethanol 250 mL solution % (v/v) = = 34% ethanol (v/v) x 100

5
**substance being dissolved**

B. Percent Solutions Percent By Mass (%(m/m)) Concentration of a solution when solute is solid sometimes expressed as percent by mass substance being dissolved total combined volume

6
B. Percent Solutions How much glucose should you use to make g of a 2.8% (m/m) solution in water? Percent (m/m) = 2.8% Solution = g unknown g glucose 2000. g solution 2.8 = = g glucose x 100

7
**substance being dissolved**

C. Molarity Concentration of a solution most often used by chemists substance being dissolved total combined volume

8
C. Molarity 2M HCl What does this mean?

9
**D. Molarity Calculations**

LITERS OF GAS AT STP Molar Volume (22.4 L/mol) MASS IN GRAMS MOLES NUMBER OF PARTICLES Molar Mass (g/mol) 6.02 1023 particles/mol Molarity (mol/L) LITERS OF SOLUTION

10
**D. Molarity Calculations**

How many moles of NaCl are required to make 0.500L of 0.25M NaCl? 0.500 L sol’n 0.25 mol NaCl 1 L sol’n = mol NaCl

11
**D. Molarity Calculations**

How many grams of NaCl are required to make 0.500L of 0.25M NaCl? 0.500 L sol’n 58.44 g NaCl 1 mol NaCl 0.25 mol NaCl 1 L sol’n = 7.3 g NaCl

12
**D. Molarity Calculations**

Find the molarity of a 250 mL solution containing 10.0 g of NaF. 10.0 g NaF 1 mol NaF 41.99 g NaF = 0.95 M NaF .25 L sol’n

13
E. Dilution Preparation of a desired solution by adding water to a concentrate Moles of solute remain the same

14
E. Dilution What volume of 15.8M HNO3 is required to make 250 mL of a 6.0M solution? GIVEN: M1 = 15.8M V1 = ? M2 = 6.0M V2 = 250 mL WORK: M1 V1 = M2 V2 (15.8M) V1 = (6.0M)(250mL) V1 = 95 mL of 15.8M HNO3

15
F. Molality mass of solvent only 1 kg water = 1 L water

16
**G. Molality Calculations**

Find the molality of a solution containing 75 g of MgCl2 in 250 mL of water. 75 g MgCl2 1 mol MgCl2 95.21 g MgCl2 0.25 kg water = 3.2m MgCl2

17
**G. Molality Calculations**

How many grams of NaCl are req’d to make a 1.54m solution using kg of water? 0.500 kg water 1.54 mol NaCl 1 kg water 58.44 g NaCl 1 mol NaCl = 45.0 g NaCl

18
**H. Preparing Solutions 1.54m NaCl in 0.500 kg of water**

500 mL of 1.54M NaCl mass 45.0 g of NaCl add water until total volume is 500 mL mass 45.0 g of NaCl add kg of water 500 mL water 45.0 g NaCl 500 mL mark volumetric flask

19
H. Preparing Solutions Copyright © NT Curriculum Project, UW-Madison (above: “Filling the volumetric flask”)

20
H. Preparing Solutions Copyright © NT Curriculum Project, UW-Madison (above: “Using your hand as a stopper”)

21
**H. Preparing Solutions 250 mL of 6.0M HNO3 by dilution**

measure 95 mL of 15.8M HNO3 95 mL of 15.8M HNO3 combine with water until total volume is 250 mL 250 mL mark Safety: “Do as you oughtta, add the acid to the watta!” or AA – add acid! water for safety

22
**Solution Preparation Mini-Lab**

Turn in one paper per team. Complete the following steps: A) Show the necessary calculations. B) Write out directions for preparing the solution. C) Prepare the solution. For each of the following solutions: 1) mL of 0.50M NaCl 2) 0.25m NaCl in mL of water 3) mL of 3.0M HCl from 12.0M concentrate. (don’t actually prepare this one!)

Similar presentations

© 2021 SlidePlayer.com Inc.

All rights reserved.

To make this website work, we log user data and share it with processors. To use this website, you must agree to our Privacy Policy, including cookie policy.

Ads by Google