The Mole. Chemical Quantities

Transcription

1 The Mole Chemical Quantities

2 How Much vs What Is It? Quantitative Analysis -gives answers in a numerical form tells exactly how much Qualitative Analysisgives answers about a compounds without using numbers what is it?

3 Measuring Matter A. By counting Apples Eggs Donuts

4 Measuring Matter B. Weighing Bulk candy Meats by the pound Peanut butter 16 oz jar

5 Measuring Matter C. Taking a volume Gallon of milk Quart of Orange juice 2 liter bottle of pop

6 Measuring Matter Units that represent certain numbers Pair = 2 Dozen = 12 Gross = 144 Ream = 500

7 Measuring Matter The mole is just like this it represents a number. Mole A unit that represents 6.02 x representative particles.

8 The number of particles in a Mole Counting atoms, ions, molecules, and formula units is impractical! Too small! Representative Particles - DEFINE Atoms, ions, formula units, or molecules.

9 Counting Representative Particles Since counting representative particles is impossible, a chemist will count particles using the mole. The mole is equal to 6.02 x anythings.

10 Avogadro s Number How many representative particles are contained in 1 mole? 6.02 x This is an experimentally determined number. It is called AVOGADRO S NUMBER in honor of this Italian scientist.

11 Sample Calculations Refer to Notepack Page 2.

12 The Mass of One Mole Atomic Mass- the mass of one atom Formula Mass- the mass of a formula unit (ionic compound) Molecular Mass- the mass of a molecule (molecular compound)

13 Gram Atomic Mass Define G.A.M. The amount of an element needed to weigh out exactly one mole of atoms of that element. What is the gram atomic mass of carbon? What is the gram atomic mass of hydrogen? What is the gram atomic mass of sulfur?

14 Gram molecular mass Define G.M.M. the amount of a molecular compound needed to weigh out exactly one mole of molecules of that compound. What is the gmm of sulfur trioxide? What is the gmm of hydrogen? What is the gmm of carbon dioxide?

15 Gram Formula Mass Define GFM the amount of an ionic compound needed to weigh out exactly one more of formula units of that compound. What is the gfm of sodium chloride? What is the gfm of ammonium carbonate? What is the grm of potassium oxide?

16 Section 1 Review Problems Refer to bottom of page 3 in notes.

17 The Molar Mass of a Substance Molar Mass- refers to the mass of any element or compound Generic for saying, atomic mass formula mass molecular mass

18 Molar Mass There are situations where molar mass doesn t work well. For example, what is the molar mass of oxygen? DON T KNOW What is better? Asking for the gram atomic mass or the gram molecular mass List the 7 diatomic molecules for review

19 Using Molar Mass to convert between moles and mass Sample calculations on page 4

20 Molar volume of a mole of gas Unlike liquids and solids, the volumes of moles of gases are much more predictable under the same physical conditions of temperature and pressure. We report standard conditions to report volumes of gases

21 Standard Temperature and Pressure Zero degrees Celsius and kilopascals (kpa) are the values of STP. ONE MOLE OF ANY GAS AT STANDARD CONDITIONS OCCUPIES A VOLUME OF 22.4 LITERS. This quantity is called the MOLAR VOLUME

22 Molar Volume Examples Refer to page 5 for examples here.

23 Density of Gases at STP The density of a gas is usually measured in units of grams per liter. (g/l) We can use the experimentally determined density of a gas at STP to calculate the molar mass of the gas. Sample problems Page 5

24 The Mole Map Multi-step Conversions Please refer to additional handout for practices here.

25 Percent Composition and Chemical Formulas The relative amounts of each element in a compound are expressed as the percent composition, or the percent by mass of each element in a compound Examples Problems page 6 and 7

26 Using Percent as a Conversion Factor You can use percent composition to calculate the number of grams of an element contained in a specific amount of a compound. To do this, you multiply the mass of the compound by a conversion factor that is based on the percent composition. Example problems page 7

27 Calculating Empirical Formulas Define Empirical Formula The lowest whole number mole-ratio of elements in a compound Define Molecular Formula The true formula of a compound the way we find it in nature. It may or may not match its empirical formula

28 Practice Problems Refer to page 7 and 8 in notes.