3 Multiple Choice 5 points 4Al+3S_(2)arrow 2Al_(2)S_(3) If 20 moles of Al are used, how many moles of S_(2) would be needed? 19molS_(2) 10molS_(2) 3molS_(2) 15molS_(2)

To determine how many moles of \( S_2 \) are needed when 20 moles of Al are used, we need to use the stoichiometric relationship from the balanced chemical equation:<br /><br />\[ 4Al + 3S_2 \rightarrow 2Al_2S_3 \]<br /><br />From the equation, we see that 4 moles of Al react with 3 moles of \( S_2 \).<br /><br />We can set up a proportion to find the number of moles of \( S_2 \) needed for 20 moles of Al:<br /><br />\[<br />\frac{4 \text{ moles of } Al}{3 \text{ moles of } S_2} = \frac{20 \text{ moles of } Al}{x \text{ moles of } S_2}<br />\]<br /><br />Now, solve for \( x \):<br /><br />\[<br />4x = 3 \times 20<br />\]<br /><br />\[<br />4x = 60<br />\]<br /><br />\[<br />x = \frac{60}{4}<br />\]<br /><br />\[<br />x = 15<br />\]<br /><br />So, 15 moles of \( S_2 \) are needed for 20 moles of Al.<br /><br />The:<br />15 \text{ mol } S_2 \]