Stoichiometric calculations study nots
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This document discusses stoichiometric calculations involving mole-to-mole and mole-to-mass conversions using balanced chemical equations. It provides an example of calculating the moles of hydrogen gas produced from a given number of moles of potassium in the reaction 2K(s) + 2H2O(l) → 2KOH(aq) + H2(g). It also shows how to determine the moles and mass of carbon dioxide produced from a given amount of reactant in the combustion reaction C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g). The document explains that mole ratios derived from balanced equations allow converting between known
Stoichiometric calculations study nots
- 1. Name:……………………………… Grade: ……………10………….. Subject: Chemistry Date ……………………… Chapter 11 :Stoichiometric Section 2 : Stoichiometric calculations Stoichiometric mole-to-mole conversion Reaction between potassium and water 2K(s) + 2 H 2 O(l) → 2KOH(aq) + H 2 (g) From the balanced equation, you know that two moles of potassium yield one mole of hydrogen. Q1 : how much hydrogen is produced if only 0.0400 mol of potassium is used? Because the given substance is in moles and the unknown substance to be determined is also in moles, this problem involves a mole-to-mole conversion. To solve the problem, you need to know how the unknown moles of hydrogen are related to the known moles of potassium. Mole ratios are used as conversion factors to convert the known number of moles of one substance to the unknown number of moles of another substance in the same reaction.
- 2. Several mole ratios can be written from the equation, but the correct one is So, Known Unknown K= 0.0400 mole H2 = ? moles Answer the following: - For the following equation C 3 H 8 (g) + O 2 (g) → C O 2 (g) + H 2 O(g) How many moles of C O 2 are produced when 10.0 mol of C 3 H 8 are burned in excess oxygen in a gas grill? The answer 1- Balance the equations 2- Follow the way shown above So C 3 H 8 (g) + 5 O 2 (g) → 3C O 2 (g) + 4 H 2 O(g) Known Unknown C 3 H 8 = 10.0 moles C O 2 = ? moles
- 4. Stoichiometric mole-to-mass conversion Now, suppose you know the number of moles of a reactant or product in a reaction and you want to calculate the mass of another product or reactant. This is an example of a mole-to-mass conversion. Example: Determine the mass of sodium chloride (NaCl), commonly called table salt, produced when 1.25 mol of chlorine gas ( Cl 2 ) reacts with sodium The answer : 1- Write the balanced chemical equation 2Na(s) + C l 2 (g) → 2NaCl(s) 2- Known Unknown 1.25 mol Cl2 ? grams of NaCl 3- Find the moles of NaCl by using mole ratio 4- Convert moles of NaCl to grams by multiplying by the molar mass