Question

The bright-red color of highway safety flares comes from strontium ions in salts such as Sr(NO3)2 and SrCO3. Burning a flare produces strontium ions in excited states, which then emit red photons at 606 nm and several wavelengths between 636 and 688 nm. Calculate the energy (in Joules per mole) of the 664 nm emission.

Answer 1

Answer:

180309 J/mol

Explanation:

The energy given off by a proton can be expressed as:

• E = hc/λ

Where h is Planck's constant, c is the speed of light and λ is the wavelenght.

Now we calculate the energy of a proton with a 664 nm emission (keep in mind that 664nm = 664x10⁻⁹m):

• E = 6.626x10⁻³⁴J·s * 3x10⁸m/s ÷ 664x10⁻⁹m = 2.99x10⁻¹⁹ J

That is the energy of one proton of one atom, now we multiply that value by Avogadro's number to find the value in Joules per mole:

• 2.99x10⁻¹⁹ J * 6.023x10²³ = 180309 J/mol