Download presentation

Presentation is loading. Please wait.

Published byKristian Bell Modified over 7 years ago

1
Solution Concentration Concentration – how much solute dissolved in amount of solvent Concentration – how much solute dissolved in amount of solvent what is difference between concentrated and diluted?

2
Concentration 3 different units of concentration 3 different units of concentration a)percent by mass b) molarity (M) c) molality (m)

3
Percent by mass Formula FormulaOR

4
Percent by mass Ex prob: If 3.6 g NaCl is dissolved in 100 g H 2 O, what is the percent by mass? Ex prob: If 3.6 g NaCl is dissolved in 100 g H 2 O, what is the percent by mass? solute What is the solute? NaCl What is the solvent? H2OH2OH2OH2O

5
Percent by mass Mass of solute (NaCl) = Mass of solute (NaCl) = 3.6 g Mass solvent (H 2 O) = Mass solvent (H 2 O) = 100 g Mass solution = Mass solution = 3.6 + 100 = 103.6 g

6
Percent by mass Percent by mass = 3.6 g x x 100 103. 6 g = 3.5 % NaCl

7
Molarity Defn - # of moles per liter of solution Defn - # of moles per liter of solution Formula mol solute Formula mol solute L solution L solution unitmol = M (capital M) unitmol = M (capital M) L

8
Molarity Ex prob #1 Molarity Ex prob #1 A solution has a volume of 250 mL and has 0.70 mol NaCl. What is the molarity? A solution has a volume of 250 mL and has 0.70 mol NaCl. What is the molarity? 2.8 mol/L or 2.8 M 0.250 L = 0.70 mol

9
Molarity ex prob #2 What is the molarity of a solution made of 47.3 g NaOH in 500 mL water? What is the molarity of a solution made of 47.3 g NaOH in 500 mL water? step 1: convert grams to moles 47.3 g NaOH 40 g NaOH 1 mol NaOH = 1.1825 mol NaOH

10
Molarity ex prob #2 Step 2: divide moles by volume (L) 2.37 mol/L NaOH or 2.37 M NaOH 0.500 L = 1.1825 mol

11
Molarity ex prob #3 How many moles of solute are present in 1.5 L of 2.4 M NaCl? How many grams? How many moles of solute are present in 1.5 L of 2.4 M NaCl? How many grams? # moles = volume x molarity 1.5 L L 2.4 mol NaCl x = 3.6 mol NaCl

12
Molarity ex prob #3 moles to grams moles to grams 3.6 mol NaCl 1 mol NaCl 58.5 g NaCl = 210.6 g NaCl

13
Molality Defn - # moles of solute in one kg solvent Defn - # moles of solute in one kg solvent Formulamol solute Formulamol solute kg solvent Unitsmol = m (lower case m) Unitsmol = m (lower case m) kg kg

14
Molality ex problem What is the molality of a solution with 8.4 g NaCl in 255 g of water? What is the molality of a solution with 8.4 g NaCl in 255 g of water? Step 1: convert grams to moles 8.4 g NaCl 58.5 g NaCl 1 mol NaCl = 0.14 mol NaCl

15
Molality ex problem Step 2: divide by mass (kg) 0.55 mol/kg NaCl or 0.55 m NaCl 0.255 kg = 0.14 mol NaCl

16
Diluting Solutions Defn – add more solvent to original solution Defn – add more solvent to original solution Formula Formula M 1 V 1 = M 2 V 2 M 1 is more concentrated than M 2

17
Diluting Solutions What volume of a 2.0 M stock solution is needed to make 0.50 L of a 0.300 M solution? What volume of a 2.0 M stock solution is needed to make 0.50 L of a 0.300 M solution? M1=M1= V1=V1= M2=M2= V2=V2= 2.0 M0.300 M ? 0.50 L (2.0 M) V 1 = (0.300 M)(0.50 L) V 1 = 0.075 L

18
Diluting Solutions If you dilute 20.0 mL of a 3.5 M solution to make 100.0 mL of solution, what is the molarity of the dilute solution? If you dilute 20.0 mL of a 3.5 M solution to make 100.0 mL of solution, what is the molarity of the dilute solution? M1=M1= V1=V1= M2=M2= V2=V2= 3.5 M? 20.0 mL 100 mL (3.5 M)(20.0 mL) = M 2 (100.0 mL) M 2 = 0.7 M

Similar presentations

© 2023 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