Stoichiometry

To start the equation must be balanced. Balanced means the same number of each type of atom before and after the arrow. Zn + HCl  ZnCl2 + H2 2 x 1 Zn H Cl 1 2 Multiply to even the sides. The number used to multiply the number of atoms becomes the coeffiecent. Zn + 2 HCl  ZnCl2 + H2

You will start with one of these The road map is to help you navigate through stoichiometry How many moles of HCl is needed to react with 6 mol of Zn? The number, measurement unit and substance in the question statement determine what to use to start. You will start with one of these Zn is now substance A. Because the unit is mol the 6 goes in the second circle. 1 mol A 6 ____ g A = ___ mol A Molar g A mass Find the molar mass from the periodic table

The road map is to help you navigate through stoichiometry This ratio comes from the balanced equation How many moles of HCl is needed to react with 6 mol of Zn A Zn + HCl  ZnCl2 + H2 1 2 2 ratio is 1 Zn to 2 HCl 12 ____ g A 1 mol A 6 ___ mol B = ____ mol B = ___ mol A Molar g A mass ____ mol A Zn is substace A The queston is about HCl so HCl is substance B There is no number in front of Zn so it gets a 1

You will start with one of these The road map is to help you navigate through stoichiometry How many moles of HCl is needed to react with 100 grams of Zn? The number, measurement unit and substance in the question statement determine what to use to start. You will start with one of these Zn is now substance A. Because the unit is grams the 100 goes in the first circle. 100 1 mol A ____ g A = ___ mol A Molar g A mass Find the molar mass from the periodic table

Molar Mass only needs calculated if using grams. Zn + 2 HCl  ZnCl2 + H2 If you need the molar mass (gram formula mass). Look up the mass of each element on the periodic table. H = 1.008 g Cl = 35.45 g Zn = 65.37 g Calculate the molar mass of substance in the equation. Zn = 65.37 g H2 = 1.008 x 2 = 2.016 HCl = 1.008 + 35.45 = 36.458 ZnCl2 = 65.37 + 2 (35.45) = 136.27 Molar Mass only needs calculated if using grams.

How many moles of HCl is needed to react with 100 grams of Zn? HCl is substance B How many moles of HCl is needed to react with 100 grams of Zn? This ratio comes from the balanced equation Zn is substance A Zn + HCl  ZnCl2 + H2 1 2 2 ratio is 1 Zn to 2 HCl 1 mol A 100 1.53 ___ mol B 3.06 ____ g A = ____ mol A = _____ mol B ___ mol A g A Find the molar mass from the periodic table 65.37g Zn = 1 mol Zn 65.37

The road map is to help you navigate through stoichiometry HCl is substance B in grams How many grams of HCl is needed to react with 6 mol of Zn? Find the molar mass from the periodic table Zn is substance A in mol Zn + HCl  ZnCl2 + H2 1 2 2 1 Mol HCl = 36.458g HCl 36.458g This ratio comes from the balanced equation ratio is 1 Zn to 2 HCl Molar g B mass 1 mol A 6 ___ mol B 12 = _____ g B 437.496 ____ g A = ____ mol A = ___ mol B Molar A mass ___ mol A 1 mol B Find the molar mass from the periodic table 65.37g Zn = 1 mol Zn Not needed substance A is mol

The road map is to help you navigate through stoichiometry HCl is substance B in grams How many grams of HCl is needed to react with 100 g of Zn? Find the molar mass from the periodic table Zn is substance A in grams Zn + HCl  ZnCl2 + H2 1 2 2 1 Mol HCl = 36.458g HCl 36.458g This ratio comes from the balanced equation ratio is 1 Zn to 2 HCl Molar g B mass 1 mol A 100 1.53 ___ mol B = ____ g B 111.56 ____ g A = ____ mol A = ____ mol B 3.06 Molar A mass ___ mol A 1 mol B Find the molar mass from the periodic table 65.37g Zn = 1 mol Zn 65.37g A