Conversions to the Max! The study of quantitative relationships between the amounts of reactants used and the amount of products formed by a chemical reaction What do you need to know How to find molar mass of compoundscheck! How to balance an equationcheck! How to do a basic conversioncheck! 4 Fe + 3 O 2 --> 2 Fe 2 O 3 First, to understand, lets find the massof the reactants 4 mole Fe56 g Fe x = 224 g Fe 11 mole Fe 3 mole O 2 32 g O 2 x= 96 g O 2 11 mole O 2 224 g + 96 g = 320 g 2 mole Fe 2 O g Fe 2 O 3 x 11 mole Fe 2 O 3 = 320 g Fe 2 O 3 Therefore, the mass of the products equals the mass of the reactants If you have a balanced chemical equation, you only need to know the mass of ONE of the reactants or products in order to determine the mass of ALL others in the equation. Each of the elements/compounds in the equation can be made into a mole ratio Example: 2 K + Br 2 2 KBr 2 mole K = 1 mole Br 2 What are the other mole ratios in this equation? 2 mole K = 2 mole KBr 1 mole Br 2 = 2 mole KBr All of these can make a conversion factor Using the same equation: 2 K + Br 2 2 KBr How many moles of potassium bromide would form if you start with 3.2 moles Br 2 ? 3.2 moles Br 2 2 moles KBr x 11 mole Br 2 = 6.4 moles KBr Using the same equation: 2 K + Br 2 2 KBr How many grams of potassium bromide would form if you start with 2.5 moles K? 2.5 mole K 2 mole KBr 119 g KBr x x 1 2 mole K 1 mole KBr = g KBr Using the same equation: 2 K + Br 2 2 KBr How many grams of potassium bromide would form if you start with 25.7 g of potassium? 25.7 g K1 mole K 2 mole KBr 119 g KBr x x x 1 39 g K 2 mole K 1 mole KBr = 78.4 g KBr Using the same equation: 2 K + Br 2 2 KBr How many grams of potassium bromide would form if you start with 11.9 g of bromine? 11.9 g Br 2 1 mole Br 2 2 mole KBr 99 g KBr x x x g Br 2 1 mole Br 2 1 moleKBr = g KBr