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what is the atomic mass of an element if 4.00 grams of it contains 2.98x10^22 atoms

Respuesta :

Atomic mass is the same as the grams per mole. 2.98x10²² is 0.0495 mol (2.98e22 ÷ 6.02e23). If we have 4 g/0.0495 mol, that's 80.81 g/mol, so the atomic mass is 80.81 amu. Make sense?

Answer: The molar mass of the element is 80.8 g/mol

Explanation:

We are given:

Number of atoms = [tex]2.98\times 10^{22}[/tex]

According to mole concept:

[tex]6.022\times 10^{23}[/tex] number of atoms are contained in 1 mole of an element

So, [tex]2.98\times 10^{22}[/tex] number of atoms will be contained in [tex]\frac{1}{6.022\times 10^{23}}\times 2.98\times 10^{22}=0.0495mol[/tex] of an element

To calculate the molar mass for given number of moles, we use the equation:

[tex]\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}[/tex]

Given mass of element = 4.00 g

Moles of an element = 0.0495 moles

Putting values in above equation, we get:

[tex]0.0495mol=\frac{4.00g}{\text{Molar mass of element}}\\\\\text{Molar mass of an element}=\frac{4.00g}{0.0495mol}=80.8g/mol[/tex]

Hence, the molar mass of the element is 80.8 g/mol