Multiple Choice
In the reaction C_3H_8 + 5 O_2 → 3 CO_2 + 4 H_2O, how many moles of water (H_2O) will be produced if 1.2 mol of oxygen (O_2) reacts with excess propane (C_3H_8)?
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3. Chemical Reactions
Stoichiometry
Multiple Choice
How many grams of aluminum (Al) must react with excess sulfuric acid (H_2SO_4) to produce 2.6 L of hydrogen gas (H_2) at STP?
A
8.1 g
B
6.0 g
C
4.7 g
D
2.6 g
Verified step by step guidance1
Write the balanced chemical equation for the reaction between aluminum and sulfuric acid: 2Al + 3H_2SO_4 \(\rightarrow\) Al_2(SO_4)_3 + 3H_2.
Identify the volume of hydrogen gas produced (2.6 L) and recall that at STP (Standard Temperature and Pressure), 1 mole of any gas occupies 22.4 L.
Calculate the moles of hydrogen gas produced using the formula: moles H_2 = \(\frac{\text{volume of }\) H_2}{22.4 \(\text{ L/mol}\)} = \(\frac{2.6}{22.4}\).
Use the mole ratio from the balanced equation to find moles of aluminum needed: from 3 moles of H_2, 2 moles of Al react, so moles Al = \(\frac{2}{3}\) \(\times\) \(\text{moles H}\)_2.
Calculate the mass of aluminum required by multiplying moles of Al by its molar mass (approximately 27 g/mol): mass Al = moles Al \(\times\) 27 \(\text{ g/mol}\).
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