If you have 1 mole of N2 (or any other gas for that matter) under STP conditions it will occupy a volume of 22.4 L. This is known as the “standard molar volume”. So, if you know the number of moles of gas that you have, you can use a simple ratio (1 mole : 22.4 L) to determine the volume of the gas
The STP conditions refer to the standard temperature and pressure. Pressure values at 1 atmosphere and temperature at 0 ° C are used and are reference values for gases. And in these conditions 1 mole of any gas occupies an approximate volume of 22.4 liters.
So, if you have 1 mole of the N2 gas under STP conditions, it means that this gas will occupy a volume of 22.4 L.
The heat required to completely melt the given substance, platinum, we just have to convert first the given mass in mole and multiply the answer to its molar heat of fusion.. Hf = mass x (1/molar mass) x molar heat of fusion Hf = (85.5 g) x (1 mole/195.08 g) x 4.70 kcal/mol Hf = 2.06 kcal
