The Mole Molar Conversions

A. What is the Mole? A large amount!!!! VERY A counting number (like a dozen) Avogadro’s number 1 mol = 6.02  1023 particles (atoms, molecules, or formula units) A large amount!!!! VERY

B. Molar Mass Mass of 1 mole of an element or compound. Molar Mass is equal to atomic mass, but the unit for molar mass is grams/mole (g/mol)

B. Molar Mass Examples Use 2 Decimal Places carbon 12.01 g/mol aluminum zinc 12.01 g/mol 26.98 g/mol 65.39 g/mol

B. Molar Mass Examples water H2O 2(1.008) + 16.00 = 18.02 g/mol sodium chloride H2O 2(1.008) + 16.00 = 18.02 g/mol NaCl 22.99 + 35.45 = 58.44 g/mol

B. Molar Mass Examples sodium bicarbonate NaHCO3 sucrose NaHCO3 22.99 + 1.01 + 12.01 + 3(16.00) = 84.01 g/mol C12H22O11 12(12.01) + 22(1.01) + 11(16.00) = 342.34 g/mol

(atoms, molecules or formula units) C. Molar Conversions 1 mole Molar mass 6.02  1023 1 mole MASS IN GRAMS MOLES NUMBER OF PARTICLES (atoms, molecules or formula units) Molar mass 1 mole 1 mole 6.02 x 1023

C. Molar Conversion Examples How many moles of carbon are in 26 g of carbon? 26 g C 1 mol C 12.01 g C = 2.2 mol C

C. Molar Conversion Examples How many molecules are in 2.50 moles of C12H22O11? 6.02  1023 molecules 1 mol 2.50 mol = 1.51  1024 molecules C12H22O11

C. Molar Conversion Examples Find the mass of 2.1  1024 molecules of NaHCO3. 2.1  1024 molecules 1 mol 6.02  1023 molecules 84.01 g 1 mol = 290 g NaHCO3

C. Mole Conversion Examples How many moles are represented by 11.5 g of C2H5OH? How many molecules is this? What is the mass of 9.30 moles of SiH4? Convert 8.00 x 1020 molecules of H2 to moles.

Answers 0.25 mole 1.51 x 1023 molecules 298.81 g 1.33 x 10-3 mole or 0.00133 mole

C. Molar Conversion Examples Find the mass of 1.00 Fe atom 1 mole Fe = 55.85g 1 mole Fe = 6.02 x 1023 atom 1.00 atom Fe 55.85 g 1 mole 6.02 x 1023 atoms 1 mole = 9.28 x 10-23 g/atom

C. Molar Conversions = 9.075 x 1023 atoms How many Oxygen atoms are there in 50.25 g of CaCO3? 50.25g CaCO3 6.02 x 1023atoms O 1 mol CaCO3 3 mol O 100.09 g 1 mol CaCO3 1 mol O = 9.075 x 1023 atoms

The Mole-Volume Relationship

The Volume of a Gas Many of the chemicals we deal with are gases They are difficult to mass Two things effect the volume of a gas Temperature and pressure We need to compare gases at the same temperature and pressure

Standard Temperature and Pressure (STP) 0°C and 1 atmosphere (atm) of pressure At STP, 1 mole of any gas occupies 22.4 L Called the molar volume 1 mole = 22.4 L of any gas at STP

Practice examples What is the volume of 4.59 mole of CO2 gas at STP? How many moles is 5.67 L of O2 at STP? What is the volume of 8.8 g of CH4 gas at STP?

Molarity –Molar Volume of… Solutions! Molarity = moles of solute liter of solution M= n V n = moles of solute V = volume (L) of solution Solution = solute + solvent

Molarity Examples How many moles of NaCl are in 0.65 L of 1.20 M NaCl solution? 0.78 moles NaCl How many moles of HCl are there in 2.43 L of 0.25 M HCl (aq)? 0.61 moles HCl

Molarity Examples How many grams of HF are there in 0.55 L of 1.5 M HF solution? 17 g How many grams of HNO3 are there in 2.50 L of 5.00 M HNO3 (aq)? 788 g

Molarity Examples Calculate the molarity of a solution made by dissolving 23.4 g of sodium sulfate in 125 ml of solution (hint: you need to find the formula of sodium sulfate) 23.4 g Na2SO4  0.165 mol 125 ml  0.125 L M = mol / L M = 0.165mol / 0.125 L 1.32 M

Molarity Examples Calculate the molarity of a solution made by dissolving 5.00 g of C6H12O6 in enough water to make 100.0 ml of solution 0.280 M

Molarity Examples How many grams of Na2SO4 are required to make 0.350 L of a 0.500 M solution of Na2SO4? 24.9 g Na2SO4