How much potassium nitrate has to dissolve in water to absorb 105 kj of heat? there are 4.184 kj/kcal. also note the answer is to be reported in kg?

Lattice energy of potassium nitrate (KNO3) = -163.8 kcal/mol

Hydration energy of KNO3 = -155.5 kcal/mole

Heat of solution is the amount of heat absorbed by water when 1 mole of KNO3 is dissolved in it

Heat of solution = Hydration energy - Lattice energy

                           = -155.5 -(-163.8) = 8.3 kcal/mol

1 kcal/mol = 4.184 kJ/mole

Therefore, 8.3 kcal/mole = 4.184 * 8.3 = 34.73 kJ/mol

Now,  34.73 kJ of heat is absorbed when 1 mole of KNO3 is dissolved

The given 105 kJ of heat would correspond to : 105/34.73 = 3.023 moles of KNO3

Molar mass of KNO3 = 101.1 g/mole

Mass of KNO3 = Molar mass * moles

                       = 101.1 * 3.023 = 305.63 g = 0.3056 kg    

water at room temperature is flowing through a pipe with pressure taps located 10 ft apart along one section of the pipe, which are connected to a mercury (s=13.6) manometer.

the answer is b because, investigating whether another species of moth also drinks tears might be interesting, but it would not directly explain why this species of moth does.

to explain why this species of moth drinks tears, the scientist could ask: "what nutrients that moths need are in elephant tears? "

the scientist could experiment with moth repellent or oter ways to keep the moths away, but that would not answer his original question.