Answer:
ΔH = +26.08 kJ/mol
Explanation:
The change in enthalpy (ΔH) is given in J/mol, and can be calculated for dissolution by the equation:
ΔH = m(water)*Cp*ΔT/n(solute)
The mass of water is the density multiplied by the volume
m = 1g/mL * 25.0mL = 25.0 g
The number of the moles is the mass divided by the molar mass. Knowing the molar masses of the elements:
N = 14 g/mol x 2 = 28
H = 1 g/mol x 4 = 4
O = 16 g/mol x 3 = 48
NH₄NO₃ = 80 g/mol
n = 1.25/80 = 0.015625 mol
So,
ΔH = 25*4.18*(25.8 - 21.9)/0.015625
ΔH = 26,083.2 J/mol
ΔH = +26.08 kJ/mol
Answer: Option C) potassium
Explanation:
According to the reactivity series of metals, potassium K is the most reactive and electropositive metal. it is followed by sodium Na, Magnesium Mg, and Calcium Ca.
Thus, the descending order of reactivity is as follows: K > Na > Mg > Ca which makes potassium displaces the less reactive elements from their respective solutions during chemical reactions.
The formula for aluminum fluoride is
That means that there is 1 Aluminum and 3 fluorde ions in 1 molecule. The 3 does not effect the Aluminum at all.
The Answer is A
Answer:
Because X-rays have wavelengths similar to the size of atoms