1. General, Organic, and Biological Chemistry Fourth Edition Karen Timberlake 1.10 Density Chapter 1 Chemistry and Measurements © 2013 Pearson Education, Inc. Lectures

2. © 2013 Pearson Education, Inc. Chapter 1, Section 10 2 Density  compares the mass of an object to its volume.  is the mass of a substance divided by its volume.  are measured in g/L for gases.  are measured in g/cm 3 or g/mL for solids and liquids. Density expression: Density

3. © 2013 Pearson Education, Inc. Chapter 1, Section 10 3 Densities of Common Substances

4. © 2013 Pearson Education, Inc. Chapter 1, Section 10 4 Density Calculations

5. © 2013 Pearson Education, Inc. Chapter 1, Section 10 5 Calculating Density If a 0.258-g sample of HDL has a volume of 0.215 cm 3, what is the density, in g/cm 3, of the HDL sample? Step 1 State the given and needed quantities. Analyze the Problem. Step 2 Write the density expression. GivenNeed 0.258 g HDL 0.215 cm 3 HDL density in g/cm 3 of HDL

6. © 2013 Pearson Education, Inc. Chapter 1, Section 10 6 Calculating Density If a 0.258-g sample of HDL has a volume of 0.215 cm 3, what is the density, in g/cm 3, of the HDL sample? Step 3 Express mass in grams and volume in milliliters (mL) or cm 3. Step 4 Substitute mass and volume into the density expression and calculate the density.

7. © 2013 Pearson Education, Inc. Chapter 1, Section 10 7 Osmium is a very dense metal. What is its density in g/cm 3 if 50.0 g of osmium has a volume of 2.22 cm 3 ? A. 2.25 g/cm 3 B. 22.5 g/cm 3 C. 111 g/cm 3 Learning Check

8. © 2013 Pearson Education, Inc. Chapter 1, Section 10 8 Osmium is a very dense metal. What is its density in g/cm 3 if 50.0 g of osmium has a volume of 2.22 cm 3. Step 1 State the given and needed quantities. Analyze the Problem Step 2 Write the density expression. Solution GivenNeed 50.0 g osmium 2.22 cm 3 density g/cm 3

9. © 2013 Pearson Education, Inc. Chapter 1, Section 10 9 Osmium is a very dense metal. What is its density in g/cm 3 if 50.0 g of osmium has a volume of 2.22 cm 3. Step 3 Express mass in grams and volume in cm 3. Step 4 Substitute into the density expression. Solution

10. © 2013 Pearson Education, Inc. Chapter 1, Section 10 10 Measuring Density of Solids Volume displacement is the volume of a solid calculated from the volume of water displaced when it is submerged.

11. © 2013 Pearson Education, Inc. Chapter 1, Section 10 11 Measuring Density Measure the mass of the solid before submerging it in water to determine its volume. The density of this zinc object is calculated from its mass and volume.

12. © 2013 Pearson Education, Inc. Chapter 1, Section 10 12 What is the density (g/cm 3 ) of 48.0 g of a metal if the level of water in a graduated cylinder rises from 25.0 mL to 33.0 mL after the metal is added? A. 0.17 g/cm 3 B. 6.0 g/cm 3 C. 380 g/cm 3 33.0 mL 25.0 mL object Learning Check

13. © 2013 Pearson Education, Inc. Chapter 1, Section 10 13 What is the density (g/cm 3 ) of 48.0 g of a metal if the level of water in a graduated cylinder rises from 25.0 mL to 33.0 mL after the metal is added? Step 1 State the given and needed quantities. Analyze the Problem. Step 2 Write the density expression. Solution

14. © 2013 Pearson Education, Inc. Chapter 1, Section 10 14 What is the density (g/cm 3 ) of 48.0 g of a metal if the level of water in a graduated cylinder rises from 25.0 mL to 33.0 mL after the metal is added? Step 3 Express mass in grams and volume in cm 3. Solution

15. © 2013 Pearson Education, Inc. Chapter 1, Section 10 15 What is the density (g/cm 3 ) of 48.0 g of a metal if the level of water in a graduated cylinder rises from 25.0 mL to 33.0 mL after the metal is added? Step 4 Substitute mass and volume into density expression. Answer: B Solution

16. © 2013 Pearson Education, Inc. Chapter 1, Section 10 16 Sink or Float Ice floats in water because the density of ice is less than the density of water. Aluminum sinks in water because its density is greater than the density of water.

17. © 2013 Pearson Education, Inc. Chapter 1, Section 10 17 Density can be written as a conversion factor. Problem Solving using Density

18. © 2013 Pearson Education, Inc. Chapter 1, Section 10 18 Density can be used as a conversion factor. A density of 3.8 g/mL, can be written as an equality, or written as conversion factors. Problem Solving using Density

19. © 2013 Pearson Education, Inc. Chapter 1, Section 10 19 Problem: Density as a Conversion Factor If the density of milk is 1.04 g/mL, how many grams of milk are in 0.50 qt of milk? Step 1 State the given and needed quantities. Analyze the Problem.

20. © 2013 Pearson Education, Inc. Chapter 1, Section 10 20 Problem: Density as a Conversion Factor If the density of milk is 1.04 g/mL, how many grams of milk are in 0.50 qt of milk? Step 2 Write a plan to calculate needed quantity. volume US–Metric density mass factor factor Step 3 Write equalities and conversion factors.

21. © 2013 Pearson Education, Inc. Chapter 1, Section 10 21 Problem: Density as a Conversion Factor If the density of milk is 1.04 g/mL, how many grams of milk are in 0.50 qt of milk? Step 4 Set up the problem to calculate the needed quantity.

22. © 2013 Pearson Education, Inc. Chapter 1, Section 10 22 The density of octane, a component of gasoline, is 0.702 g/mL. What is the mass, in kg, of 875 mL of octane? A. 0.614 kg B. 614 kg C. 1.25 kg Learning Check

23. © 2013 Pearson Education, Inc. Chapter 1, Section 10 23 The density of octane, a component of gasoline, is 0.702 g/mL. What is the mass, in kg, of 875 mL of octane? Step 1 State the given and needed quantities. Analyze the Problem Solution

24. © 2013 Pearson Education, Inc. Chapter 1, Section 10 24 The density of octane, a component of gasoline, is 0.702 g/mL. What is the mass, in kg, of 875 mL of octane? Step 2 Write a plan to convert the given unit to the needed unit. Solution kg mL Density Factor Metric Factor

25. © 2013 Pearson Education, Inc. Chapter 1, Section 10 25 The density of octane, a component of gasoline, is 0.702 g/mL. What is the mass, in kg, of 875 mL of octane? Step 3 State the equalities and conversion factors. Solution

26. © 2013 Pearson Education, Inc. Chapter 1, Section 10 26 The density of octane, a component of gasoline, is 0.702 g/mL. What is the mass, in kg, of 875 mL of octane? Step 4 Set up the problem to cancel units and calculate the answer. Answer: B Solution

27. © 2013 Pearson Education, Inc. Chapter 1, Section 10 27 Specific Gravity (sp gr)  is the relationship between the density of a substance and the density of water.  is determined by dividing the density of the sample by the density of water.  is a unitless quantity. Specific Gravity

28. © 2013 Pearson Education, Inc. Chapter 1, Section 10 28 Specific Gravity is measured by an instrument called a hydrometer. Specific Gravity

29. © 2013 Pearson Education, Inc. Chapter 1, Section 10 29 Which of the following samples of metals will displace the greatest volume of water? A B C 25 g of aluminum 2.70 g/mL 45 g of gold 19.3 g/mL 75 g of lead 11.3 g/mL Learning Check

30. © 2013 Pearson Education, Inc. Chapter 1, Section 10 30 The correct answer is A. Plan: Calculate the volume for each metal, and select the metal sample with the greatest volume. Solution 25 g of aluminum 2.70 g/mL