The balanced equation for the reaction between Na and H₂SO₄ is as follows;
2Na + H₂SO₄ ---> Na₂SO₄ + H₂
Stoichiometry of Na to H₂SO₄ is 2:1
the molar concentration of H₂SO₄ is 6.0 M
This means that in 1 L of H₂SO₄ - there are 6.0 mol of H₂SO₄
Therefore in 750 mL -

Number of H₂SO₄ moles reacted - 4.5 mol
According to stoichiometry,
1 mol of H₂SO₄ reacts with 2 mol of Na
Therefore 4.5 mol reacts with 2x4.5= 9 mol of Na
Mass of Na reacted - 9 mol x 23 g/mol = 207 g of Na is required
We first calculate the energy contained in one photon of this light using Planck's equation:
E = hc/λ
E = 6.63 x 10⁻³⁴ x 3 x 10⁸ / 590 x 10⁻⁹
E = 3.37 x 10⁻²² kJ/photon
Now, one mole of atoms will excite one mole of photons. This means that 6.02 x 10²³ photons will be excited
(3.37 x 10⁻²² kJ/photon) x (6.02 x 10²³ photons / mol)
The energy released will be 202.87 kJ/mol
The answer to this question is A
The question above is simply asking us to convert the value from calories into kilojoules. Therefore, we need some factor to multiply to be able to convert it to such units. For calories to kJ, the factor would be 4.184.
2700 cal ( 4.184 kJ/cal) = 11296.8 kJ