Get personalized answers to your specific questions with IDNLearn.com. Get the information you need from our experts, who provide reliable and detailed answers to all your questions.

Q7. Some helium is heated from [tex]20^{\circ}C[/tex] to [tex]100^{\circ}C[/tex]. If 520 MJ of energy have been transferred into the thermal energy store of the helium, what mass of helium is involved?

Helium has a specific heat capacity of [tex]5200 \, \text{J} / ( \text{kg} \cdot ^{\circ}\text{C} )[/tex].


Sagot :

To determine the mass of helium involved when it is heated from [tex]\(20^{\circ} C\)[/tex] to [tex]\(100^{\circ} C\)[/tex] with 520 MJ of energy, we can use the formula that relates energy, mass, specific heat capacity, and temperature change. The formula is:

[tex]\[ Q = m \cdot c \cdot \Delta T \][/tex]

where:
- [tex]\( Q \)[/tex] is the energy transferred (in joules),
- [tex]\( m \)[/tex] is the mass of helium (in kilograms),
- [tex]\( c \)[/tex] is the specific heat capacity (in joules per kilogram per degree Celsius),
- [tex]\( \Delta T \)[/tex] is the change in temperature (in degrees Celsius).

Let's break down the steps to solve for the mass [tex]\( m \)[/tex]:

1. Convert the energy transferred from megajoules to joules:
Since 1 MJ (megajoule) is equal to [tex]\( 10^6 \)[/tex] joules, you need to convert 520 MJ to joules:
[tex]\[ Q = 520 \times 10^6 \, \text{J} \][/tex]

2. Calculate the change in temperature ([tex]\( \Delta T \)[/tex]):
The initial temperature ([tex]\( T_i \)[/tex]) is [tex]\(20^{\circ} C\)[/tex] and the final temperature ([tex]\( T_f \)[/tex]) is [tex]\(100^{\circ} C\)[/tex]:
[tex]\[ \Delta T = T_f - T_i \][/tex]
[tex]\[ \Delta T = 100^{\circ} C - 20^{\circ} C \][/tex]
[tex]\[ \Delta T = 80^{\circ} C \][/tex]

3. Rearrange the energy formula to solve for mass ([tex]\( m \)[/tex]):
[tex]\[ m = \frac{Q}{c \cdot \Delta T} \][/tex]

4. Substitute the given values into the rearranged formula:
Given that [tex]\( Q = 520 \times 10^6 \)[/tex] J, [tex]\( c = 5200 \,\text{J/kg} \cdot ^\circ C \)[/tex], and [tex]\( \Delta T = 80^{\circ} C\)[/tex]:
[tex]\[ m = \frac{520 \times 10^6 \, \text{J}}{5200 \, \text{J/kg} \cdot ^\circ C \times 80^{\circ} C} \][/tex]

5. Perform the calculation:
[tex]\[ m = \frac{520 \times 10^6}{5200 \times 80} \][/tex]
[tex]\[ m = \frac{520 \times 10^6}{416000} \][/tex]
[tex]\[ m = 1250 \, \text{kg} \][/tex]

Therefore, the mass of helium involved is [tex]\( 1250 \)[/tex] kg.
Thank you for using this platform to share and learn. Don't hesitate to keep asking and answering. We value every contribution you make. Your search for solutions ends at IDNLearn.com. Thank you for visiting, and we look forward to helping you again.