Multiple Choice
When 0.066 mole of sodium (Na) is completely reacted with water according to the equation 2 Na + 2 H_2O → 2 NaOH + H_2, how many moles of hydrogen gas (H_2) are produced?
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3. Chemical Reactions
Stoichiometry
Multiple Choice
Given excess oxygen, how many moles of H_2O can be produced from 12.5 moles of C_4H_{10} in the complete combustion reaction: C_4H_{10} + O_2 ightarrow CO_2 + H_2O?
A
12.5 moles
B
50.0 moles
C
25.0 moles
D
37.5 moles
Verified step by step guidance1
Write the balanced chemical equation for the complete combustion of butane (C_4H_{10}). The general form is: C_4H_{10} + O_2 \(\rightarrow\) CO_2 + H_2O.
Balance the carbon atoms first: since there are 4 carbons in C_4H_{10}, place a coefficient of 4 in front of CO_2: C_4H_{10} + O_2 \(\rightarrow\) 4CO_2 + H_2O.
Balance the hydrogen atoms next: there are 10 hydrogens in C_4H_{10}, so place a coefficient of 5 in front of H_2O (because each water molecule has 2 hydrogens): C_4H_{10} + O_2 \(\rightarrow\) 4CO_2 + 5H_2O.
Balance the oxygen atoms last: on the right side, there are (4 \(\times\) 2) + (5 \(\times\) 1) = 8 + 5 = 13 oxygen atoms. Since O_2 is diatomic, divide 13 by 2 to get the coefficient for O_2: C_4H_{10} + \(\frac{13}{2}\) O_2 \(\rightarrow\) 4CO_2 + 5H_2O. To avoid fractions, multiply the entire equation by 2 if desired.
Use the mole ratio from the balanced equation between C_4H_{10} and H_2O to find the moles of water produced. For every 1 mole of C_4H_{10}, 5 moles of H_2O are produced. Multiply 12.5 moles of C_4H_{10} by 5 to get the moles of H_2O.
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