Multiple Choice
What is the first step in solving a stoichiometric problem?
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3. Chemical Reactions
Stoichiometry
Multiple Choice
What mass of Aluminum (Al) is needed to react completely with 35.0 mL of 2.0 M Hydrochloric acid (HCl), given the reaction: 2 Al + 6 HCl → 2 AlCl3 + 3 H2?
A
0.63 g
B
1.26 g
C
0.84 g
D
0.42 g
Verified step by step guidance1
Determine the number of moles of HCl present in the solution using the formula: \( \text{moles of HCl} = \text{Molarity} \times \text{Volume in Liters} \). Convert 35.0 mL to liters by dividing by 1000.
Use the stoichiometry of the balanced chemical equation \( 2 \text{Al} + 6 \text{HCl} \rightarrow 2 \text{AlCl}_3 + 3 \text{H}_2 \) to find the mole ratio between Al and HCl. From the equation, 2 moles of Al react with 6 moles of HCl.
Calculate the moles of Al needed using the mole ratio: \( \text{moles of Al} = \frac{2}{6} \times \text{moles of HCl} \).
Convert the moles of Al to mass using the molar mass of Aluminum. The molar mass of Al is approximately 26.98 g/mol. Use the formula: \( \text{mass of Al} = \text{moles of Al} \times \text{molar mass of Al} \).
Compare the calculated mass of Al with the given options to determine the correct answer.
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