Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
I. The Mole A. Quantity of Particles 1. The SI unit for the _______________________ is the __________ German : ______________________ Latin: ___________________________ 2. 1 mole of a substance = _____________________ items of that substance. ex: 1 mole of m & m’s is ___________________ m & m’s 1 mole of water molecules is _______________ water molecules 1 mole of carbon atoms is _________________ atoms of carbon the mole is a quantity unit like other quantity units, units of measurement ex: 1 dozen m & m is 12 m & m 1 gross of m & m’s is 144 m & m’s 3. This number of items is called ________________ number (N A) NA = 602, 000, 000, 000, 000, 000, 000, 000 NA = 6.02 x 1023 in scientific notation 4. Related to chemistry Avogadro's number = 6.02 x 1023 particles such as _________ _________________________________ and ________________ (ionic compounds) 1 mole of watermelon seeds would fit inside a watermelon slightly larger than the size of the ___________ 1 liter of water contains approximately ________ moles of H2O which is about 3.3 x 1025 molecules of H2O Chapter 6 1 of 11 5. Calculations (uses conversion factors) How many carbon atoms are in 1 mol of carbon? How many carbon atoms are in 0.1 mol of carbon? B. Mole to mole ratios The number of moles of one substance can be compared to another. These comparisons can be within a formula or between two formulas within a balanced equation 1. Mole ratios within a formula ex CO2 has 1 mole of C atoms and 2 moles of oxygen atoms O2 has 2 moles of oxygen atoms How many O atoms are in 1 mole of O2? How many Al+3 ions are in 1 mole of Al2O3? 2. C. Mole ratios in a balanced equation mole to mole ratios in a balanced equation will be discussed later Mass of the mole (molar mass) Remember the periodic chart and the atomic weights of each of the elements. Just a reminder, the weights from the chart is for ___________ of the element. Chapter 6 2 of 11 1. For example, 1 atom of hydrogen weighs ____________ (atomic mass units). What is the mass in grams of 1 atom of Hydrogen? This is a __________________ of the world. 2. how to count atoms on a regular basis? The most usual way to count atoms is by ___________________________________________ If we weigh out ____________ of H, ____________ of Cl and ____________ of Mg, we have the ________________________ of each one of these elements. This number of atoms is called __________________ number (NA) and has the value __________________. Use the atomic weight from the chart and express it in grams. So one mole of Mg is ___________. [1 amu is 1.66054 x 10-24 g so 1 g = 6.02 x 1023 amu (inverse)] Chapter 6 3 of 11 3. The mole represents a conversion between grams and atomic mass units. _____________________ is the weight in ________ of one mole The mass in grams of any substance is the same number as its formula or atomic mass. (the sum of the atomic masses of the atoms in a formula) If the atomic mass of a substance is Q amu, then 1: 2: 1 mole of the substance has a mass of Q grams 1 mole of the substance contains 6.02 x 1023 unit particles What is the mass of 1 mol of C ? What is the mass of 1 mol of Al2O3 ? (talk later how to get mass of Al2O3) What is the mass of 0.1 mol of C ? The Mole SI unit for amount of substance 1 mole = 6.022 x 1023 particles 1 mole = Formula or atomic mass in grams Quantity of particles Chapter 6 Mole Mass of a substance 4 of 11 II Molar mass, formula weight, molecular weight A. _________________________ (MM) the mass of mole of any substance expressed in grams element - 1 mole of potassium atoms = _______________ The molar mass of potassium is ________________ compound such as CO2 need to calculate formula weight B. _________________________(FW) (Formula mass) the sum of the atomic masses of the atoms in a formula in ___________ (includes molecules and ionic compounds) C. __________________________ (MW) (Molecular mass, subset of FW) the sum of the atomic masses of the atoms in a molecule in _________ Therefore: ex: MW of CO2 ex: FW of Ca(OH)2 Chapter 6 5 of 11 III Problem solving strategies 1. Identity what you know, write it down 2. Identity what you want to find out 3. Identity any intermediate steps and make a plan of the sequence of conversions calculate FW etc., unit conversions 4. If need to calculate something, don’t limit yourself with sig fig from your calculation, Check the number you have from the question (unless you have to!!) 5. Units, carry them through Solve problems : Chapter 6 1. What is the mass in grams of 0.64 mol of Ca(OH)2 ? 2. How many mol are in 0.64 g of Ca(OH)2 3. How many oxygen atoms are in 1 mol of Ca(OH)2 4. How many grams of Oxygen are in 0.25 mol CO2? 6 of 11 Mole conversion chart Compound or Atom Number and Types of Particles Mass in grams 1 mole carbon __________________ atoms ____________ g 1 mole oxygen (O) __________________ atoms ____________ g 1 mole oxygen (O2) __________________ molecules ____________ g __________________ atoms ____________ g 0.1 mole carbon __________________ atoms ____________ g 1 mole aluminum oxide (Al2O3) _________________ formula units ____________ g __________________ Al+3 ions ____________ g __________________ O-2 ions ____________ g __________________ ions Chapter 6 7 of 11 IV Mass Percent Composition and Empirical formulas A. Definitions 1. ____________________________________ percentages by mass of the elements in a compound. ex: white solid is 53% K and 47 % O This means in 100 g, 53 g is K and 47 g is O 2. ______________________________________ - actual number of atoms of each element ex: benzene ___________, and acetylene _________ 3. ________________________ - simplest formula, simplest whole number ratios, ratio ex: both _______ The atom ratios are proportional to the number of moles of each kind of atom present!! B. Determining Mass Percent Composition from Formula 1. Calculate molar mass 2. Divide total mass of each element by the molar mass x100 ex: What is the percent composition of H2O? Chapter 6 8 of 11 C. D. Chapter 6 Determining Mass % Composition from Experimental Data 1. Calculate mass of compound formed. 2. Divide mass of each element by total mass x 100 ex: 24.6 g of mercury combine with 8.7 g of chlorine. Calculate % composition. Determination of Empirical Formulas Using Percent composition Determined from experimental data 1. Assume definite starting amount (100.0 g) 2. Use molar masses to convert grams of each element to moles: 3. Divide the number of moles of each element by the smallest of the quantities 4. Multiply values from step 3 by the smallest number to make whole numbers 9 of 11 Example 1 : Given a compound is composed of 58.81% Ba, 13.73 % S, and 27.46 % O, find the empirical formula Example 2: Given grams of a product: A 6.50 g sample of Chromium was heated in pure oxygen. The compound produced had a mass of 9.50 g. What is the empirical formula? Chapter 6 10 of 11 E. Molecular formulas Remember that empirical formulas give a ratio of the elements in the compound only! So if have molar mass of a substance and an empirical formula, can calculate the molecular formula: Example 1 : The molar mass of benzene is 78.0 g, and the empirical formula is CH, what is the molecular formula? Example 2: The molar mass of gasoline is 114.0 g, and the empirical formula is C4H9, what is the molecular formula? Chapter 6 11 of 11