Answer:
Supervision of weights and measures promotes accurate measurements of goods and services to ensure that everybody gets a fair trade in the marketplace. Not so coincidentally it also is a deterrent to ensure that traders are being honest in their trade practises.
Explanation:
First step is to balance the reaction equation. Hence we get
P4 + 5 O2 => 2 P2O5
Second, we calculate the amounts we start with
P4: 112 g = 112 g/ 124 g/mol – 0.903 mol
O2: 112 g = 112 g / 32 g/mol = 3.5 mol
Lastly, we calculate the amount of P2O5 produced.
2.5 mol of O2 will react with 0.7 mol of P2O5 to produce 1.4
mol of P2O5.
This is 1.4 * (31*2 + 16*5) = 198.8 g
Answer:
Chemists make observations on the macroscopic a scale that lead to conclusions about microscopic features
Explanation:
Many important chemical observations are made on the macroscopic scale. This is because, many of the scientific equipments available are not presently able to provide direct evidence about microscopic processes. Evidences obtained from macroscopic observations could serve as important insights into the nature of certain microscopic processes.
This is evident in the study of the structure of the atom. Most of the evidences that led to the deduction of the atomic structure were obtained from macroscopic evidence but ultimately provided important information about the microscopic structure of the atom.
Answer:
Property of an element by virtue of which it exists in two or more forms which differ only in their physical properties is known as allotropy. Allotropes are the different physical forms in which the element can exist. Allotropes are different physical forms of the same element.
Also-
Allotropes are different forms of the same element in the molecular level. Isotopes are different forms of atoms of the same chemical element. The key difference between allotropes and isotopes is that allotropes are considered at the molecular level, whereas isotopes are considered at the atomic leve
Explanation:
~Hope this helps~
Answer:
91.6 nm
Explanation:
The energy of the hydrogen atom can be calculated by the emission of a photon. When an electron is excited it goes from to the next energetic level, and when it returns to its ground state, it emits a photon. Hydrogen has only one electron, which is at the level n = 1. So, the equation is given:
E = (-21.7x10⁻¹⁹J)/1²
E = -21.7x10⁻¹⁹J
The energy of the photon is the energy absorbed, and because of that is positive (the opposite of the energy released by the electron). This energy can be calculated by:
E = h*c/λ
Where h is the Planck's constant (6.626x10⁻³⁴ J.s), c is the speed of the light (3.00x10⁸ m/s), and λ is the wavelength of the photon.
21.7x10⁻¹⁹ = 6.626x10⁻³⁴ * 3.00x10⁸/λ
λ = 9.16x10⁻⁸ m
λ = 91.6 nm
