Download presentation

1
**8.4 Percent Concentration**

Chapter 8 Solutions 8.4 Percent Concentration

2
**Concentration The concentration of a solution**

is the amount of solute dissolved in a specific amount of solution concentration = amount of solute amount of solution

3
**Mass Percent Concentration**

Mass percent (m/m) concentration is the percent by mass of solute in a solution calculated using the formula: Mass = mass of solute(g) x 100% percent mass of solute(g) + mass of solvent(g) Mass percent = mass of solute(g) x 100% mass of solution(g)

4
Mass of Solution

5
**Calculating Mass Percent**

The calculation of mass percent (m/m) requires the grams of solute (g of KCl) and grams of solution (g of KCl solution) g of KCl = g g of solvent (water) = g g of KCl solution = g 8.00 g of KCl (solute) x 100% = 16.0% (m/m) 50.00 g of KCl solution

6
**Guide to Calculating Solution Concentrations**

7
**Learning Check 1) 15.0%(m/m) Na2CO3 2) 6.38%(m/m) Na2CO3**

A solution is prepared with 15.0 g of Na2CO3 and 235 g of H2O. What is the mass percent (m/m) of the solution? 1) 15.0%(m/m) Na2CO3 2) 6.38%(m/m) Na2CO3 3) 6.00%(m/m) Na2CO3

8
Solution 3) 6.00% (m/m) Na2CO3 STEP 1 Given: 15.0 g of Na2CO3; 235 g of H2O Need: mass percent (m/m) of Na2CO3 solution STEP 2 Plan: mass percent(m/m) = g of solute x 100% g of solution Calculate mass of solution = g g = 250 g of Na2CO3 solution

9
**Solution (continued) STEP 3 Write equalities and conversion factors:**

15.0 g of Na2CO3 = 250 g of solution 15.0 g Na2CO3 and g solution 250 g solution g of Na2CO3 STEP 4 Set up problem: mass = g Na2CO3 x 100 = 6.00%(m/m) Na2CO3 percent g solution (m/m)

10
**Volume Percent The volume percent (v/v) is**

percent by volume of solute (liquid) in a solution volume % (v/v) = volume of solute x 100% volume of solution volume solute (mL) in 100 mL of solution. volume % (v/v) = mL of solute 100. mL of solution

11
**Mass/Volume Percent The mass/volume percent (m/v) is**

mass/volume % (m/v) = grams (g) of solute x 100% volume(mL) of solution mass of solute(g) in 100 mL solution = g of solute mL of solution

12
**Preparation of a Solution: Mass/Volume Percent**

13
**Percent Conversion Factors**

Two conversion factors can be written for each type of percent concentration.

14
**Learning Check Write two conversion factors for each solution:**

A % (m/m) NaOH B % (v/v) ethanol C. 4.8% (m/v) HCl

15
**Solution A. 8.50% (m/m) NaOH 8.50 g NaOH and 100 g solution**

100 g solution g NaOH B % (v/v) ethanol 5.75 mL ethanol and mL solution 100 mL solution mL ethanol C. 4.8% (m/v) HCl 4.8 g HCl and mL HCl 100 mL solution g HCl

16
**Guide to Using Concentration to Calculate Mass or Volume**

17
**Example of Using Percent Concentration (m/m) Factors**

How many grams of NaCl are needed to prepare 225 g of a 10.0% (m/m) NaCl solution? STEP 1 Given: 225 g of solution; 10.0% (m/m) NaCl Need: g of NaCl (solute) STEP 2 Plan: g of solution g of NaCl 17

18
**Solution STEP 3 Write equalities and conversion factors:**

10.0 g of NaCl = 100 g of NaCl solution 10.0 g NaCl and 100 g NaCl solution 100 g NaCl solution g NaCl STEP 4 Set up problem to cancel grams of solution: 225 g NaCl solution x g NaCl = 22.5 g of NaCl g NaCl solution

19
**Learning Check 1) 10.5 g of NaOH 2) 75.0 g of NaOH 3) 536 g of NaOH**

How many grams of NaOH are needed to prepare g of 14.0% (m/m) NaOH solution? 1) g of NaOH 2) g of NaOH 3) 536 g of NaOH

20
**Solution STEP 1 Given: 75.0 g of NaOH solution;**

14.0% (m/m) NaOH solution Need: g of NaOH (solute) STEP 2 g of solution g of NaOH STEP 3 Write equalities and conversion factors: 14.0 g of NaOH = 100 of NaOH solution 14.0 g NaOH and 100 g NaOH solution 100 g NaOH solution g NaOH STEP 4 Set up problem to cancel the grams of solution: 75.0 g NaOH solution x g NaOH = 10.5 g of NaOH g NaOH solution

21
**Learning Check 1) 2.56 mL 2) 12.9 mL 3) 39.1 mL**

How many milliliters of a 5.75% (v/v) ethanol solution can be prepared from 2.25 mL of ethanol? 1) mL 2) mL 3) mL

22
**Solution STEP 1 Given: 2.25 mL of ethanol (solute)**

5.75% (v/v) ethanol solution Need: mL of ethanol solution STEP 2 Plan: mL of ethanol mL of solution STEP 3 Write equalities and conversion factors: 100 mL of solution = 5.75 mL of ethanol 5.75 mL ethanol and mL solution 100 mL solution mL ethanol STEP 4 Set up problem to cancel the mL of ethanol: 2.25 mL ethanol x 100 mL solution = mL of solution mL ethanol

23
**Example Using Percent Concentration (m/v) Factors**

How many mL of a 4.20% (m/v) will contain 3.15 g KCl? STEP 1 Given: g of KCl (solute) 4.20% (m/v) KCl solution Need: mL of KCl solution STEP 2 Plan: g of KCl mL of KCl solution 23

24
**Using Percent Concentration(m/v) Factors (continued)**

STEP 3 Write equalities and conversion factors: 4.20 g KCl = 100 mL of KCl solution 4.20 g KCl and mL KCl solution 100 mL KCl solution g KCl STEP 4 Set up the problem: 3.15 g KCl x 100 mL KCl solution = mL of KCl g KCl

25
**Learning Check How many grams of NaOH are needed to prepare 125**

mL of a 8.80% (m/v) NaOH solution? 1) g of NaOH 2) g of NaOH 3) g of NaOH

26
**Solution 2) 11.0 g of NaOH STEP 1 Given: 125 mL of NaOH (solution)**

8.80% (m/v) NaOH solution Need: g of NaOH (solute) STEP 2 Plan: mL of NaOH solution g of NaOH

27
**Solution (continued) STEP 3 Write equality and conversion factors:**

8.80 g of NaOH = 100 mL of NaOH solution 8.80 g NaOH and 100 mL NaOH solution 100 mL NaOH solution g NaOH STEP 4 Set up the problem: 125 mL NaOH solution x g NaOH 100 mL NaOH solution = 11.0 g of NaOH

Similar presentations

© 2019 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