Answer:
Mg²⁵ = 10.00%
Mg²⁶ = 45.04%
Mg²⁴ = 44.96%
Explanation:
Given data:
Atomic mass of Mg²⁶ = 25.983
Atomic mass of Mg²⁵ = 24.986
Atomic mass of Mg²⁴ = 23.985
Abundance of Mg²⁵ = 10.00%
Abundance of Mg²⁶ = ?
Abundance of Mg²⁴ = ?
Solution:
Average atomic weight of Mg = 25.983 + 24.986+ 23.985 / 3
Average atomic weight of Mg = 74.954/3
Average atomic weight of Mg = 24.985 amu
Abundance of
Mg²⁵ = 10.00
Mg²⁶ = x
Mg²⁴ = 100- 10 - x = 90 -x
Formula:
Average atomic mass = (abundance of 1st isotope × its atomic mass) +(abundance of 2nd isotope × its atomic mass) + (abundance of 3rd isotope × its atomic mass) / 100
24.985 = (0.1×24.986)+(90-x×23.985) + ( x ×25.983 ) /100
24.985 = 249.86 + 2158.65 - 23.985x + 25.983x / 100
24.985 = 2408.51 + 1.998 x / 100
2498.5 = 2408.51 + 1.998 x
1.998 x = 2498.5 - 2408.51
1.998 x = 89.99
x = 89.99 /1.998
x = 45.04
Now we put the value of x:
Mg²⁵ = 10.00
Mg²⁶ = x (45.04)
Mg²⁴ = 90 -x (90 - 45.04 = 44.96)
Explanation:
Molar mass
The mass present in one mole of a specific species .
The molar mass of a compound , can easily be calculated as the sum of the all the individual atom multiplied by the number of total atoms .
(a) P₄
Molar mass of of the atoms are -
Phosphorous , P = 31 g/mol
Molecular mass of P₄ = ( 4 * 31 ) = 124 g/mol .
(b) H₂O
Molar mass of of the atoms are -
Hydrogen , H = 1 g/mol
oxygen , O = 16 g/mol.
Molecular mass of H₂O = ( 2 * 1 ) + ( 1 * 16 ) = 18 g/mol
(c) Ca(NO₃)₂
Molar mass of of the atoms are -
calcium , Ca = 40 g/mol
nitrogen, N = 14 g/mol
oxygen , O = 16 g/mol.
Molecular mass of Ca(NO₃)₂ = ( 1 * 40 ) + ( 2 * 14 ) + ( 6 * 16 ) = 164 g/mol.
(d)CH₃CO₂H (acetic acid)
Molar mass of of the atoms are -
Carbon , C = 12 g/mol.
oxygen , O = 16 g/mol.
Hydrogen , H = 1 g/mol
Molecular mass of CH₃CO₂H =( 2 * 12 ) + (2 * 16 ) + (4 * 1 ) = 60 g/mol.
(e) C₁₂H₂₂O₁₁ (sucrose, cane sugar).
Molar mass of of the atoms are -
Carbon , C = 12 g/mol.
oxygen , O = 16 g/mol.
Hydrogen , H = 1 g/mol
Molecular mass of C₁₂H₂₂O₁₁ = (12 * 12 ) + ( 22 * 1 ) + ( 11 * 16 ) = 342 g/mol.
A wave is a disturbance that carries energy from one place to another. Matter is NOT carried with the wave! A wave can move through matter (a medium). If it must have a medium, it is called a mechanical wave.
