Question

exam lesson name: energy conversions
exam number: 700697rr
exam guidelines
exam instructions
question 14 of 20 :
select the best answer for the question.

1. based on their specific heat values, compare the amounts of energy it would take to increase the temperature of a kg of benzene and a kg of methyl alcohol by 5 degrees celsius.

a. it would take more energy to increase the temperature of methyl alcohol.
b. neither can increase temperature unless they change to a solid state first.
c. both would require much more energy than a kg of water to increase.
d. it would take more energy to increase the temperature of benzene.
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Explanation:

To solve this, we use the formula for heat energy \( Q = mc\Delta T \), where \( m \) is mass, \( c \) is specific heat, and \( \Delta T \) is temperature change. Here, \( m = 1\,\text{kg} \) and \( \Delta T = 5^\circ\text{C} \) for both substances. The specific heat of methyl alcohol (\( c_{\text{methyl alcohol}} \)) is higher than that of benzene (\( c_{\text{benzene}} \)). Since \( Q \propto c \) (when \( m \) and \( \Delta T \) are constant), a higher \( c \) means more energy is needed. So methyl alcohol requires more energy. Option B is wrong (temperature increase doesn't require phase change to solid). Option C is wrong (water has a high specific heat, so benzene and methyl alcohol need less energy than water). Option D is wrong as benzene has lower \( c \) than methyl alcohol.

Answer:

A. It would take more energy to increase the temperature of methyl alcohol.