The answer is the last one! I believe.
Answer:
7g
Explanation:
Given parameters:
Mass of sodium = 3g
Mass of chlorine = 4g
Unknown:
Total mass of sodium chloride = ?
Solution:
This problem entails the direct application of the law of conservation of mass. According to this law, it states that "matter is neither created nor destroyed in the course of a chemical reaction".
So, when sodium and chlorine combines to form sodium chloride, to are expect to produce substance with a mass which adds up to the sum of the reactants;
Mass of sodium chloride = mass of sodium + mass of chlorine
= 3g + 4g
= 7g
An electric motor produces heat while running. The amount of heat is roughly equivalent to the amount of power delivered to the motor.
Enthalpy of reaction: -41.15 kJ
Entropy change: -42.36 kJ
Answer: The freezing-point depression constant (Kf) of nitrobenzene is
Explanation:
Depression in freezing point is given by:
= Depression in freezing point
i= vant hoff factor = 1 (for non electrolyte nitrobenzene)
= freezing point constant = ?
m= molality
Weight of solvent = 20 g = 0.02 kg
mass of solute (ethanol) = 1.0 g
Molar mass of ethanol = 46 g/mol
Thus freezing-point depression constant (Kf) of nitrobenzene is