Starter S-93 What is the molar mass of H2S? How many moles of H2S would be found in 100 g? How many formula units (particles) of H2S would be in 100g?

Chapter 10 Chemical Quantities

10.1 The Mole: A Measurement of Matter Chapter 10 10.1 The Mole: A Measurement of Matter

10.1 The Mole Quantitative – yield a number value Most common methods count mass volume

10.1 The Mole Words often mean a quantity pair – 2 dozen – 12 mole?

10.1 The Mole 10.1 The Mole Mole – means a specific number of particles This is called Avogadro’s Number The unit is used for atoms molecules (covalent compounds) formula units (ionic compounds)

10.1 The Mole 10.1 The Mole To convert numbers of particles to moles we need an equality This could also be Or Depending on what type of particle you are trying to convert

10.1 The Mole 10.1 The Mole The rest is just the conversion we have always done remember – the unit you have goes on the bottom of the fraction -the unit you are converting to goes on the top So to convert 2500 atom of C to moles

10.1 The Mole 10.1 The Mole Converting from moles to partciles follows the same process How many molecules of Carbon Dioxide are in 1.55 mol?

10.1 The Mole 10.1 The Mole Convert the following quantities to moles 1. 9,487,212 formula units of AgNO3 2. 5.78x1023 atoms of Nitrogen 3. 4.1x1024 molecules of Carbon Monoxide

10.1 The Mole 10.1 The Mole Convert the following to the correct type of particle 1. 95 moles of CCl4 2. 7.211x10-3 moles of CuCO3 3. 0.08 moles of Helium

10.1 The Mole 10.1 The Mole By definition, the atomic mass of an element in grams is the mass of one mole of the element. This is called the molar mass

10.1 The Mole 10.1 The Mole For a compound we must calculate the molar mass Write down what type of atoms, and how many of each are present C 1 H 4 2. Multiply by the molar mass of each element CH4

10.1 The Mole 10.1 The Mole For a compound we must calculate the molar mass Write down what type of atoms, and how many of each are present C 1 x 12.0107g = H 4 x 1.00794g = 2. Multiply by the molar mass of each element CH4

10.1 The Mole 10.1 The Mole For a compound we must calculate the molar mass Write down what type of atoms, and how many of each are present C 1 x 12.0107g = 12.0107g H 4 x 1.00794g = 4.03176g Multiply by the molar mass of each element Add to get a total CH4

10.1 The Mole 10.1 The Mole For a compound we must calculate the molar mass Write down what type of atoms, and how many of each are present C 1 x 12.0107g = 12.0107g unit H 4 x 1.00794g = 4.03176g Multiply by the molar mass of each element Add to get a total 16.0425g CH4 CH4

Starter S-94 What is the molar mass of CO? How many moles of CO would be found in 0.56 g? How many molecules of CO would be found in 3.51 moles?

10.2 Mole-Mass and Mole-Volume Chapter 10 10.2 Mole-Mass and Mole-Volume

10.2 Mole-Mass and Mole-Volume 10.1 The Mole 10.2 Mole-Mass and Mole-Volume We don’t convert from particles to moles nearly as often as we do from moles to grams. The reason is that we usually measure the amount of a substance on the balance We need to know numbers of particles so that we can compare ratios of atom or compounds

10.2 Mole-Mass and Mole-Volume 10.1 The Mole 10.2 Mole-Mass and Mole-Volume This is just another conversion problem The equality is Again, the quantity you have goes on the bottom, the quantity you want goes on top So if you have 9.5g of Carbon Value Molar Mass = 1 mole

10.2 Mole-Mass and Mole-Volume 10.1 The Mole 10.2 Mole-Mass and Mole-Volume If you have 2.2 moles of Silver Nitrate convert to mass First we need to know the formula of Silver Nitrate Then the molar mass And finally we can convert

10.2 Mole-Mass and Mole-Volume 10.1 The Mole 10.2 Mole-Mass and Mole-Volume Try the following example: How many moles is 8.2g of Copper (II) Chloride Formula Molar mass Moles

10.2 Mole-Mass and Mole-Volume 10.1 The Mole 10.2 Mole-Mass and Mole-Volume And another one: How many grams is 2.4 mol of Iron (III) Sulfate Formula Molar mass Moles

10.2 Mole-Mass and Mole-Volume 10.1 The Mole 10.2 Mole-Mass and Mole-Volume In 1811, Amedeo Avogadro proposed Avagador’s Hypothesis – equal volumes of gases at the same temperature and pressure contain equal numbers of particles

10.2 Mole-Mass and Mole-Volume 10.1 The Mole 10.2 Mole-Mass and Mole-Volume Standard Temperature and Pressure (STP) T – 0oC or 273K P – 101.3 kPa, or 1 atm At STP the volume of one mole is 22.4L So the equality for conversion is

10.2 Mole-Mass and Mole-Volume 10.1 The Mole 10.2 Mole-Mass and Mole-Volume To do these problems, the identity of the gas doesn’t really matter. If we have 15 L of Chlorine gas The number of moles would be

10.2 Mole-Mass and Mole-Volume 10.1 The Mole 10.2 Mole-Mass and Mole-Volume If instead we calculate for a more complicated gas such as propane And we also have 15 L of propane gas The number of moles would be

Starter S-95 What is the molar mass of Pb(SO4)2? How many moles of Pb(SO4)2 would be found in 250 g? How many moles of H2 gas are found in 250 L?

10.3 Percent Composition and Chemical Formulas Chapter 10 10.3 Percent Composition and Chemical Formulas

10.1 The Mole 10.3 Percent Composition The relative amounts of the elements in a compound is called the percent composition The percent by mass of an element is the number of grams of the element divided by the mass in grams of the compound multiplied by 100%

10.1 The Mole 10.3 Percent Composition Calculating the mass percent from a formula Formula Calculate the total mass of each element mass of the compound Calculate the percent by mass for each element

10.1 The Mole 10.3 Percent Composition Calculate the mass percent Formula Mass of each element Total mass Mass Percent

Starter S-98 What is the percent by mass of the all the elements in Cu(NO3)2.

10.1 The Mole 10.3 Percent Composition Empirical Formula – smallest whole number ratio of the elements in a compound The empirical formula can be calculated from the percent composition Compound Empirical Formula H2O CH3COOH CH2O C6H12O6 S8 S

10.1 The Mole 10.3 Percent Composition To calculate the empirical formula List the elements and their percent compositions Convert the percent compositions to moles Calculate the mole ratio (divide by the smallest number of moles) Smallest Whole Number ratio Write the Formula

10.1 The Mole 10.3 Percent Composition To calculate the empirical formula Elements Convert to Moles Mole ratio Whole Number ratio Write the Formula

Starter S-99 What is the empirical formula if Lead is 59.7% Hydrogen is 2.9% Arsenic is 21.6% Oxygen is 18.4%

10.1 The Mole 10.3 Percent Composition The molecular formula can be calculated from the empirical formula and the molar mass Comparison of Empirical and Molecular Formulas Formula Classification Molar Mass CH Empirical 13 C2H2 Molecular 26 (2x13) C6H6 78 (6x13) CH2O 30 C2H4O2 60 (2x30) C6H12O6 180 (6x30)

10.1 The Mole 10.3 Percent Composition Steps in calculations (if mass=60.0g) Determine the empirical formula Calculate the mass of the empirical formula Divide the actual molar mass by this number 4. Multiply the empirical formula

Starter S-102 What is the empirical formula if Silver – 63.5% Nitrogen – 8.2 % Oxygen – 28.2% If the formula mass is 170g, what is the formula of this compound?

Starter S-103 What is the empirical formula if Carbon – 49.5% Hydrogen – 5.2% Nitrogen – 28.9% Oxygen – 16.5% What if the molecular formula, if the molar mass is 194g?