I always thought it was a mixture but can also be a compound
In reality closed systems do not exist. In the theoretical case of a closed system the total energy of the system would stay the same (matter and particles are considered energy to). More important: the energy level throughout the whole system will eventually be evenly spread and uniform (entropy), therefore no energy differential is left to perform work.
Use of the empirical formula
Zn(s) + 2HCl(aq) --> ZnCl2(aq) + H2(g) From the balanced chemical equation, 2 moles of HCl is required to react with 1 mole of Zn Mass of Zn = 9.55 g Molar mass of Zinc = 65.41 g/mol Number of moles = mass / molar mass Moles of Zn = 9.55 / 65.41 = 0.146 mol Moles of HCl required = 2 x moles of Zn = 2 x 0.146 = 0.292 mol
Answer : The mass of calcium chloride (in g) needed is, 1.92 grams.
Explanation : Given,
Boiling point of elevation constant for water =
Mass of water (solvent) =
Molar mass of = 110.98 g/mole
Formula used :
where,
= change in boiling point =
i = Van't Hoff factor = 3 (for electrolyte)
= boiling point constant for water
m = molality
Now put all the given values in this formula, we get
Therefore, the mass of calcium chloride (in g) needed is, 1.92 grams.