Multiple Choice
For the reaction 4Al(s) + 3O₂(g) → 2Al₂O₃(s), if you start with 8 moles of Al and 6 moles of O₂, what is the limiting reactant?
3. Chemical Reactions
Stoichiometry
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How many grams of KCl(s) are produced from the thermal decomposition of KClO3(s) when 25.0 mL of O2(g) is produced at 25°C and 1.00 atm pressure according to the chemical equation: 2 KClO3(s) → 2 KCl(s) + 3 O2(g)?
A
0.149 g
B
0.112 g
C
0.0745 g
D
0.0372 g
Verified step by step guidance1
Start by identifying the balanced chemical equation for the decomposition of potassium chlorate (KClO3): 2 KClO3(s) → 2 KCl(s) + 3 O2(g). This equation tells us the stoichiometric relationship between the reactants and products.
Use the ideal gas law to find the number of moles of O2 produced. The ideal gas law is given by: , where P is pressure, V is volume, n is moles, R is the gas constant, and T is temperature. Convert the temperature to Kelvin by adding 273.15 to the Celsius temperature.
Calculate the moles of O2 using the ideal gas law: . Use the values: P = 1.00 atm, V = 25.0 mL (convert to liters), R = 0.0821 L·atm/mol·K, and T = 298.15 K.
Using the stoichiometry from the balanced equation, determine the moles of KCl produced. From the equation, 3 moles of O2 are produced for every 2 moles of KCl. Therefore, use the ratio: to find the moles of KCl.
Convert the moles of KCl to grams using the molar mass of KCl. The molar mass of KCl is approximately 74.55 g/mol. Use the formula: to find the mass of KCl produced.
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