Which element has the greatest density at STP?
1 answer:
Answer: Option (4) is the correct answer.
Explanation:
It is known that density is mass divided by volume.
Mathematically, Density =
Since, density is directly proportional to mass. So, more is the mass of an element more will be its density.
Mass of magnesium is 24.305 g/mol.
Mass of barium is 137.327 g/mol.
Mass of beryllium is 9.012 g/mol
Mass of radium is 226 g/mol.
Hence, radium has more mass therefore it will have the greatest density at STP.
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Answer:
C. 588 nm
Explanation:
Given parameters:
Energy of the photon = 3.38 x 10⁻¹⁹J
Unknown:
Wavelength of the photon = ?
Solution:
The energy of a photon can be expressed as;
E =
hc = E x wavelength
Wavelength =
h is the Planck's constant = 6.63 x 10⁻³⁴m²kg/s
c is the speed of light = 3 x 10⁸m/s
E is the energy
Wavelength = = 5.89 x 10⁻⁷m
Answer:
The heat of formation = Heat of formation of the products - Heat of formation of the reactants
= -2323 + 104 = -2219 ≈ -2218.6 kJ/mol.
Explanation:
The law of conservation of energy states that the total energy is constant in any process. Energy may change in form or be transferred from one system to another, but the total remains the same
The heat of formation of C₃H₈ is 3C + 4 H₂ → C₃H₈ -104 kJ/mol
The heat of formation of O₂ is O₂ (g) → O₂ (g) 0 kJ/mol
The heat of formation of H₂O is H₂(g) + 1/2 O₂→ H₂O (g) -286kJ/mol
The heat of formation of CO₂ is C (s) + O₂ (g) → CO₂ (g) -393 kJ/mol
Therefore, in the given reaction we have;
C₃H₈ + 4 O₂ → 3 CO₂ + 4 H₂O
The heat of formation = Heat of formation of the products - Heat of formation of the reactants
The heat of formation = 3 × (-393) + 4 × (-286) - (-104) = -2219 ≈ -2218.6 kJ/mol.