NIS – CHEMISTRY

Lecture 61 – Lecture 62Stoichiometric Calculations

Ozgur Unal

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Using StoichiometryA recipe for banana split calls for four ingredients, each in a particular quantity: one banana, two scoops of ice cream, 50 mL of chocolate syrup and 50 mL of strawberry syrup.Write the equation for banana split..

What is needed to make five banana splits following the same recipe?

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Using StoichiometryPotassium metal reacts with water as shown.The chemical equation of reaction is:

2K (s) + 2H2O (l) 2KOH (aq) + H2 (g)If 0.04 mol of K is used in this equation, how much H2 is produced after the reaction?

To find the answer, we should find the mole ratio of H2 to K.Mole ratio of H2 to K = 1 mol of H2 / 2 mol of K0.04 mol of K * 1 mol of H2 / 2 mol of K = 0.02 mol of H2

moles of known*moles of unknown/moles of known=moles of unknown

Check out Problem Solving Strategy on page 374!!

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Using StoichiometryExample: One disadvantage of burning propane is that carbon dioxide is one of the products. The released carbon dioxide increases the concentration of CO2 in the atmosphere. How many moles of CO2 is produced when 10 moles of propane is burned in excess oxygen in a gas grill?Example: Methane and sulfur react to produce carbon disulfide, a liquid often used in the production of cellophane.Balance the equation.Calculate the moles of CS2 produced when 1.5 mol S8 is used.How many moles of H2S is produced?

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Using StoichiometryExample: Determine the mass of sodium chloride produced when 1.25 mol of chlorine gas reacts with excess sodium.

Example: Ammonium nitrate (NH4NO3), an important fertilizer, produces dinitrogen oxide (NO2) gas and H2O when it decomposes. Determine the mass of H2O produced from the decomposition of 25 g of solid NH4NO3.