Answer:
0.0321 g
Explanation:
Let helium specific heat [tex]c_h = 5.193 J/g K[/tex]
Assuming no energy is lost in the process, by the law of energy conservation we can state that the 20J work done is from the heat transfer to heat it up from 273K to 393K, which is a difference of ΔT = 393 - 273 = 120 K. We have the following heat transfer equation:
[tex]E_h = m_hc_h \Delta T = 20 J[/tex]
where [tex]m_h[/tex] is the mass of helium, which we are looking for:
[tex] m_h = \frac{20}{c_h \Delta T} = \frac{20}{5.193 * 120} \approx 0.0321 g[/tex]
