Multiple Choice
How many milliliters of 0.200 M FeCl3 are needed to react with an excess of Na2S to produce 0.172 g of Fe2S3 if the percent yield for the reaction is 65.0%?
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3. Chemical Reactions
Stoichiometry
Multiple Choice
How many molecules of H2S are required to form 79.0 g of sulfur according to the reaction: 2 H2S(g) + SO2(g) → 3 S(s) + 2 H2O(l)? Assume excess SO2.
A
2.96 x 10^24 molecules
B
4.44 x 10^24 molecules
C
7.40 x 10^23 molecules
D
1.48 x 10^24 molecules
Verified step by step guidance1
First, identify the molar mass of sulfur (S). The atomic mass of sulfur is approximately 32.07 g/mol.
Calculate the number of moles of sulfur in 79.0 g using the formula: \( \text{moles of S} = \frac{\text{mass of S}}{\text{molar mass of S}} \).
Use the stoichiometry of the balanced chemical equation: \( 2 \text{ H}_2\text{S} \rightarrow 3 \text{ S} \). This means 2 moles of \( \text{H}_2\text{S} \) produce 3 moles of \( \text{S} \). Calculate the moles of \( \text{H}_2\text{S} \) required using the ratio: \( \text{moles of H}_2\text{S} = \frac{2}{3} \times \text{moles of S} \).
Convert the moles of \( \text{H}_2\text{S} \) to molecules using Avogadro's number, \( 6.022 \times 10^{23} \text{ molecules/mol} \). Use the formula: \( \text{molecules of H}_2\text{S} = \text{moles of H}_2\text{S} \times 6.022 \times 10^{23} \).
Compare the calculated number of molecules to the given options to determine which one matches the calculated value.
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