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Using Chemical Formulas

Using Chemical Formulas. 7.3. Formula Masses. Formula Mass – for any molecule, formula unit, or ion, it is the ____ of the ________ masses of all atoms represented in its formula. H 2 O for example is H = 1.008 x 2 = 2.016 amu O = 15.999 x 1 = 15.999 amu Total = 18.015 amu.

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Using Chemical Formulas

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  1. Using Chemical Formulas 7.3

  2. Formula Masses • Formula Mass – for any molecule, formula unit, or ion, it is the ____ of the ________ masses of all atoms represented in its formula. • H2O for example is • H = 1.008 x 2 = 2.016 amu • O = 15.999 x 1 = 15.999 amu • Total = 18.015 amu

  3. Formula Masses • Try to find the mass of • KClO3 H2SO4 • Ca(NO3)2 PO43- • MgCl2

  4. Molar Masses • The mass of 1 mol of a substance in g/mol • H2O for example is • H = 1.008 x 2 = 2.016 g/mol • O = 15.999 x 1 = 15.999 g/mol • Total = 18.015 g/mol • The ___ mass is numerically = to the ___ mass

  5. Molar Mass as a Conversion Factor • You can convert grams to moles and vice versa using ______ ______ • You can also convert atoms to moles and vice versa using ___________ #

  6. Conversions • What is the mass in grams of 2.50 mol of oxygen gas? • How many moles are in 100 g of H2O? • How many moles are in 10 grams of Carbon? • How many moles are in 3.01 x 1023 molecules of CH4? • How many atoms are in 15 moles of S?

  7. Practice • How many molecules are there in the following… • 25.0 g H2SO4 • 125 g Sugar C6H12O6 • How many grams are in… • 6.5 x 1023atoms of Cu • 5.12 x 1030 molecules of CH4

  8. Percent Composition • Percent Composition – the % by mass of each _________ in a cmpd • To calculate % Comp, determine _______ mass of entire compound. • Calculate the % of each element by __________ the mass of each ___________ by the molar mass.

  9. Percent Composition • Determine the percent composition of Al and O in Al2O3. • Determine the composition of Al, S, and O in Al2(SO4)3

  10. Practice • Find the % comp of each element in the following • PbCl2Ba(NO3)2 • Find the % water in ZnSO4•7H2O • Mg(OH)2 is 54.87% O by mass. How many g of O are in 175 g of the cmpd? How many moles of O is this?

  11. Assignment Slide  • Complete the section review on page 244 numbers 1-6. This is due at the beginning of class tomorrow!

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