When the Heat gain or lose = the mass * specific heat * ΔT
and when we have the mass of gold coin= 40 g
and the specific Heat of gold= 0.13 J/g°
and ΔT = (Tf- Ti) = 10°C - 50°C = -40 °C
so by substitution:
∴Heat H = 40 g * 0.13 J/g° * -40
= - 208 J
The number of moles in a substance indicates the amount of the substance that contains the same number of particles as 12 g of the Carbon-12 isotope [or equivalent to 6.02 × 10²³] (which is used as a standard in the world of moles).
Now,
if 6.02 × 10²³ atoms are found in 1 mole ofsodium
then let 9.76 × 10¹² atoms are found in x
⇒ x = (9.76 × 10¹² ) ÷ (6.02 × 10²³)
= 1.619 × 10⁻¹¹ mol
Now, mass = moles × molar mass
∴ mass of Na = 1.619 × 10⁻¹¹ mol × 23 g/mol
= 3.72 × 10⁻¹⁰ g
