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Day 2 - Notes. Unit: Stoichiometry. Mass-mass calculations using the mole ratio. After today you will be able to…. Calculate the number of grams produced or reacted of a substance given a chemical equation. There are three steps needed for these calculations:
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Day 2 - Notes Unit: Stoichiometry Mass-mass calculations using the mole ratio
After today you will be able to… • Calculate the number of grams produced or reacted of a substance given a chemical equation
There are three steps needed for these calculations: • Convert gramsmoles (Using the MM of the known.) • Convert moles of knownmoles of unknown using the mole ratio (We learned this yesterday!) • Convertmoles of unknown grams (Using MM of the unknown.)
Mass-Mass Calculations Example: What mass of silver chloride will react with 15.0g of aluminum? __Al 1 __ AgCl 3 __ Ag + __ AlCl3 1 3 + Al Ag Cl 1 1 3 1 1 1 Review! 1Ag =107.871) K: 15.0 gAl 3 3 1Cl =35.45(1) 3 U: ? gAgCl 143.32g 1 mol Al 26.98 gAl 143.32 gAgCl 1 mol AgCl 15.0 gAl 1 3 mol AgCl 1 mol Al x x x 239g AgCl =
Mass-Mass Calculations Example: What mass of oxygen gas would be produced from the decomposition of 37.2g of lithium chlorate? __Li(ClO3) 2 __ LiCl + __ O2 3 2 1Li =6.94(1) K: 37.2 gLi(ClO3) 1Cl =35.45(1) 3O =16.00(3) U: ? gO2 90.39g 32.00 gO2 1 mol O2 1 mol Li(ClO3) 90.39 gLi(ClO3) 3 mol O2 2 mol Li(ClO3) 37.2 gLi(ClO3) 1 x x x 19.8 gO2 =
SUMMARY OF IMPORTANT POINTS: • You are calculating the mass for TWO different substances! • Molar mass (MM) is ALWAYS equal to ONE mole! • The ONLY time the number of moles is different than ONE (1) is when you are doing the MOLE RATIO STEP!
Questions? Complete WS 2 for HOMEWORK!