Question

1. how many grams of na₂s are in 4.75 moles? how many atoms are there? given:4.75 req:moles of na₂s solu:moles of na₂s = \\( \frac { g } { m m } \\) = \\( \frac { 4.75 } { 78.1 } \\) = 371. g/na₂s = 8.5785 < = 4.75 moles x 6.03×10²³×3 = 8.58 g/na₂s

Explanation:

Step1: Calculate the molar mass of \(Na_2S\)

The molar mass of \(Na\) is \(22.99\ g/mol\) and for \(S\) is \(32.07\ g/mol\).
For \(Na_2S\), \(MM=(2\times22.99)+32.07 = 45.98 + 32.07=78.05\approx78.1\ g/mol\)

Step2: Calculate the mass of \(Na_2S\)

Use the formula \(n=\frac{m}{MM}\), where \(n = 4.75\ mol\) and \(MM = 78.1\ g/mol\).
Rearrange to \(m=n\times MM\)
\(m=4.75\ mol\times78.1\ g/mol = 371\ g\)

Step3: Calculate the number of formula units of \(Na_2S\)

Use Avogadro's number \(N_A = 6.02\times 10^{23}\ units/mol\)
Number of formula units \(N=n\times N_A=4.75\ mol\times6.02\times 10^{23}\ units/mol = 2.86\times 10^{24}\) formula units

Step4: Calculate the number of atoms

In one formula unit of \(Na_2S\), there are \(2 + 1=3\) atoms.
Number of atoms \(=3\times2.86\times 10^{24}=8.58\times 10^{24}\) atoms

Answer:

The mass of \(Na_2S\) is \(371\ g\) and the number of atoms is \(8.58\times 10^{24}\) atoms.