The AHsol for NaF is 82 kJ/mol, and the lattice energy is –923 kJ/mol. If the hydration enthalpy of sodium is 21 kJ/mol more than the hydration enthalpy of fluoride, what are the hydration enthalpies for the sodium and fluoride ions? Use A
Hsol = - Hat+ H hydr
O sodium: -841 kJ/mol; fluoride: -862 kJ/mol
O sodium: -431 kJ/mol; fluoride: -410 kJ/mol
Osodium: -410 kJ/mol; fluoride: -431 kJ/mol
O sodium: -389 kJ/mol; fluoride: -410 kJ/mol

(newtons first law)

conservation of momentum law states :

momentum before collision = momentum after collision

momentum p (kg-m/s)= mass * velocity

say moving car=1 000 kg, velocity = 10 m/s then p = 1 000*10= 10 000 kg-m/s

say still car = 2 000 kg, velocity = 0 m/s then p = 2 000* 0 = 0 kg-m/s

total momentum prior to collision = 10 000 + 0 = 10 000 kg-m/s

momentum after collision = 10 000 kg-m/s

mass now = 1 000 kg+2 000 kg = 3 000 kg

10 000 = 3 000 kg* velocity m/s

10 000/3 000 = velocity

3.33 m/s = velocity after collision

an impulse is a force applied over time , momentum is exclusive of external forces and a perfect collision is implied