Calculate the amount of heat (in kJ) required to raise the temperature of an 86.0 g sample of ethanol from 108.0 K to 300.8 K. The specific heat capacity of ethanol is [tex]$242 \, \text{J/g} \cdot ^{\circ}\text{C}$[/tex].

A. 60.0 kJ
B. 21.2 kJ
C. 73.6 kJ
D. 28.4 kJ
E. 11.9 kJ



Answer :

To determine the amount of heat required to raise the temperature of an 86.0 g sample of ethanol from 108.0 K to 300.8 K, let's follow these steps:

1. Given Data:
- Mass of ethanol, [tex]\( m = 86.0 \)[/tex] g
- Initial temperature, [tex]\( T_{initial} = 108.0 \)[/tex] K
- Final temperature, [tex]\( T_{final} = 300.8 \)[/tex] K
- Specific heat capacity, [tex]\( c = 242 \)[/tex] [tex]\( \text{J} / (\text{g} \cdot ^\circ \text{C}) \)[/tex]

2. Determine the temperature change:
[tex]\[ \Delta T = T_{final} - T_{initial} \][/tex]
[tex]\[ \Delta T = 300.8 \, \text{K} - 108.0 \, \text{K} = 192.8 \, \text{K} \][/tex]

(Note: Since the temperatures are given in Kelvin and we're considering only temperature differences, the units for [tex]\( \Delta T \)[/tex] in Kelvin are equivalent to degrees Celsius for the purpose of this calculation.)

3. Convert the specific heat capacity to kJ/g°C:
[tex]\[ c_{kJ} = 242 \, \text{J} / (\text{g} \cdot ^\circ \text{C}) \times 0.001 \, \text{kJ/J} = 0.242 \, \text{kJ} / (\text{g} \cdot ^\circ \text{C}) \][/tex]

4. Calculate the heat required using the formula [tex]\( Q = mc\Delta T \)[/tex]:
[tex]\[ Q = m \times c_{kJ} \times \Delta T \][/tex]
[tex]\[ Q = 86.0 \, \text{g} \times 0.242 \, \text{kJ} / (\text{g} \cdot ^\circ \text{C}) \times 192.8 \, ^\circ \text{C} \][/tex]

5. Perform the multiplication:
[tex]\[ Q = 86.0 \, \text{g} \times 0.242 \, \text{kJ} / (\text{g} \cdot ^\circ \text{C}) \times 192.8 \, ^\circ \text{C} \][/tex]
[tex]\[ Q = 4012.5536 \, \text{kJ} \][/tex]

Therefore, the amount of heat required is approximately [tex]\( 4012.5536 \)[/tex] kJ. Comparing this value with the options provided, none of them match exactly. Therefore, it seems there might be a misunderstanding regarding the results provided or possibly a typographical error in the options.