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STOICHIOMETRY. Problem. What mass of Br 2 is produced when 45.9g of NaBr react with 12.8g of Cl to produce Br 2 and NaCl?. What do you do next?. Balance the equation Find mass of NaBr Find mole of NaBr. Incorrect. Correct. Balance. 2NaBr + Cl 2 Br 2 + 2NaCl.
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Problem • What mass of Br2 is produced when 45.9g of NaBr react with 12.8g of Cl to produce Br2 and NaCl?
What do you do next? • Balance the equation • Find mass of NaBr • Find mole of NaBr
Balance • 2NaBr + Cl2 Br2 + 2NaCl *2Na on the left and right *2Br on left and right *2Cl on left and right *Always have the same number of elements on both sides to be balanced.
Next Step? Find the mass of NaBr
And? These two numbers are the coefficients from the balanced equation. Mass of NaBr from the periodic table
SOOOOOOOOOOOO WHAT? Get massfrom periodic table Given in problem Coefficient from the balanced equation
AND? • Multiply across and divide Multiply With the answer you got from the multiplication, divide with this bottom multiplied number
Second equation:Same steps as of the first equation When you multiply across and divide with the bottom number, what do you get? • 28.8gBr2 • 2045.4gBr2 • 2.3gBr2
Find the limiting reactant • *The compound with the smallest mass is always the limiting reactant • So the limiting reactant is Cl2 • Thereforethemass of Br2 produced is 28.8g
Remember!!!!!!! • Always balance the equation first • Get the masses from the periodic table • Use the coefficients for your third step • Multiply across and divide • Solve the two equations first • The smallest number is always the limiting reactant