Questions: A balanced chemical equation indicates the proportions or ratios of the various reactants and products to one another. From the coefficients in the balanced chemical equation, we can create mole-mole ratios that relate any of the various chemicals to a different chemical.
For example, consider the following balanced chemical equation:
N2(g)+3 H2(g) rightarrow 2 NH3(g)
From this equation, there are several possible mole-mole ratios. Two of these mole-mole ratios are the following:
3 moles H2/1 mole N2 or 2 moles NH3/3 moles H2
How many moles of sodium nitride, NaN3, are needed to produce 3.94 moles of nitrogen, N2?
2 NaN3(s) rightarrow 2 Na(s)+3 N2(g)
5.91 moles of NaN3
3.94 moles of NaN3
3.80 moles of NaN3
2.63 moles of NaN3
Transcript text: A balanced chemical equation indicates the proportions or ratios of the various reactants and products to one another. From the coefficients in the balanced chemical equation, we can create mole-mole ratios that relate any of the various chemicals to a different chemical.
For example, consider the following balanced chemical equation:
\[
\mathrm{N}_{2}(\mathrm{~g})+3 \mathrm{H}_{2}(\mathrm{~g}) \rightarrow 2 \mathrm{NH}_{3}(\mathrm{~g})
\]
From this equation, there are several possible mole-mole ratios. Two of these mole-mole ratios are the following:
\[
\frac{3 \text { moles } \mathrm{H}_{2}}{1 \text { mole } \mathrm{N}_{2}} \text { or } \frac{2 \text { moles } \mathrm{NH}_{3}}{3 \text { moles } \mathrm{H}_{2}}
\]
How many moles of sodium nitride, $\mathrm{NaN}_{3}$, are needed to produce 3.94 moles of nitrogen, $\mathrm{N}_{2}$ ?
\[
2 \mathrm{NaN}_{3}(\mathrm{~s}) \rightarrow 2 \mathrm{Na}(\mathrm{~s})+3 \mathrm{~N}_{2}(g)
\]
5.91 moles of $\mathrm{NaN}_{3}$
3.94 moles of $\mathrm{NaN}_{3}$
3.80 moles of $\mathrm{NaN}_{3}$
2.63 moles of $\mathrm{NaN}_{3}$
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Solution
Solution Steps
Step 1: Identify the Mole-Mole Ratio
From the balanced chemical equation:
\[
2 \mathrm{NaN}_{3}(\mathrm{~s}) \rightarrow 2 \mathrm{Na}(\mathrm{~s}) + 3 \mathrm{~N}_{2}(g)
\]
we can identify the mole-mole ratio between sodium nitride (\(\mathrm{NaN}_{3}\)) and nitrogen (\(\mathrm{N}_{2}\)). The ratio is:
\[
\frac{2 \text{ moles } \mathrm{NaN}_{3}}{3 \text{ moles } \mathrm{N}_{2}}
\]
Step 2: Set Up the Proportion
We need to find how many moles of \(\mathrm{NaN}_{3}\) are required to produce 3.94 moles of \(\mathrm{N}_{2}\). Using the mole-mole ratio:
\[
\frac{2 \text{ moles } \mathrm{NaN}_{3}}{3 \text{ moles } \mathrm{N}_{2}} = \frac{x \text{ moles } \mathrm{NaN}_{3}}{3.94 \text{ moles } \mathrm{N}_{2}}
\]
Step 3: Solve for \(x\)
Cross-multiply to solve for \(x\):
\[
2 \times 3.94 = 3 \times x
\]
\[
7.88 = 3x
\]
\[
x = \frac{7.88}{3} = 2.6267
\]
Step 4: Round to Four Significant Digits
Round the result to four significant digits:
\[
x = 2.627
\]
Final Answer
\[
\boxed{2.63 \text{ moles of } \mathrm{NaN}_{3}}
\]