Answer :
The number of kilomoles of NaCl per 1000 kg of water is calculated by determining the molar mass of NaCl, finding the moles in 35.8 kg, converting to kilomoles, and then adjusting for the amount of water. The correct value is 6.1282 kmol per 1000 kg of water, none of the options provided are correct. Therefore, the correct answer is : (C).
To calculate the number of kilomoles of NaCl per 1000 kg of water, first determine the molar mass of NaCl. The molar mass of sodium (Na) is approximately 23.0 g/mol and that of chlorine (Cl) is approximately 35.5 g/mol. Adding these together gives us the molar mass of NaCl: 23.0 g/mol + 35.5 g/mol = 58.5 g/mol.
Now, calculate the number of moles of NaCl in 35.8 kg (or 35800 g) by dividing by the molar mass:
Number of moles of sodium chloride = (35,800 g) / (58.5 g/mol) = 612.82 moles NaCl.
To express this amount in kilomoles, divide by 1000:
612.82 moles / 1000 = 0.61282 kilomoles NaCl.
Since the question asks for the amount per 1000 kg of water, the amount already calculated is the correct value, as the given NaCl amount is based on 100 kg of water. So for 1000 kg of water, which is ten times more, we would expect ten times more NaCl.
Therefore, 0.61282 kmol x 10 = 6.1282 kmol of NaCl per 1000 kg of water. Option (b) 3.58 kmol is incorrect as the calculations give us 0.61282 kmol for 100 kg of water, which means 6.1282 kmol for 1000 kg of water.
