Answer:
Number of atoms = 5.1345 x 10²³
Explanation:
Given:
Mass of sodium = 19.6
Find:
Number of atoms
Computation:
We know that atomic mass of sodium is 22.98
So,
Number of atoms = [Mass of sodium/atomic mass of sodium]Avogadro's number
Number of atoms = [19.6 / 22.98]6.02 x 10²³
Number of atoms = 5.1345 x 10²³
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Answer:
a. x = + 2
b. x = + 3
c. x = + 2
d. x = + 3
Explanation:
The oxidation number is a formal charge assigned to an atom present in a molecule or formula unit or ion based on some arbitrary rules.
a.
<u>Hg</u>O
The oxidation number of Hg in HgO is:
x + (-2) = 0
x = +2
b.
<u>Al₄</u>C₃
The oxidation number of Al in Al<u>₄</u>C₃ is:
4x +(3 × -4) = 0
4x - 12 = 0
4x = +12
x = 12/4
x = +3
c. CrF₂
x + ( 2 × - 1) = 0
x - 2 = 0
x = + 2
d. Fe₂S₃
2x + ( 3 × - 2) = 0
2x + (-6) = 0
2x = 6
x = 6/2
x = +3
32L —> 32000g —> 727.116 Moles (rounded)
2 ways to do this
a. find %Cl in CaCl2
2 x 35.45g/mole = 70.9g Cl
70.9g Cl / 110.9g/mole CaCl2 = 63.93% Cl in CaCl2
0.6963 x 145g = 92.7g = mass Cl
b. determine moles CaCl2 present then mass Cl
145g / 110.9g/mole = 1.31moles CaCl2 present
2moles Cl / 1mole CaCl2 x 1.31moles = 2.62moles Cl
2.62moles Cl x 35.45g/mole = 92.7g Cl
A compound is a substance made up of atoms of two or more different elements joined by chemical bonds. A mixture is a combination of two or more substances that are not chemically combined.
