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Multiple Choice
The creation of liquid methanol is accomplished by the hydrogenation of carbon monoxide: CO (g) + 2 H2 (g) → CH3OH (l) ∆Hº = – 128.1 kJ How much heat (in kJ) is released when 125.0 g CO reacts with 2.32 x 102 g H2?
A
275 kJ
B
-572 kJ
C
-128 kJ
D
281 kJ
Verified step by step guidance
1
First, determine the molar mass of carbon monoxide (CO) and hydrogen (H2). The molar mass of CO is approximately 28.01 g/mol, and the molar mass of H2 is approximately 2.02 g/mol.
Calculate the number of moles of CO and H2 using their respective masses. For CO, use the formula: moles of CO = mass of CO / molar mass of CO. For H2, use: moles of H2 = mass of H2 / molar mass of H2.
Identify the limiting reactant by comparing the mole ratio from the balanced chemical equation to the calculated moles. The balanced equation shows that 1 mole of CO reacts with 2 moles of H2.
Use the limiting reactant to determine the amount of heat released. Since the reaction releases 128.1 kJ per mole of CO reacted, multiply the moles of the limiting reactant by the enthalpy change (∆Hº = -128.1 kJ/mol) to find the total heat released.
Ensure the sign of the heat change is negative, indicating that the reaction is exothermic and releases heat. This will give you the total heat released in kJ.