Question

Calculate the grams of sulfur in 8.022x1025 formula units of Lithium sulfate.

Please answer with correct number of sig figs, and scientific notation

Answer 1

A mole of Lithium sulfate contains 6.02×10²³ molecules.

Proportion 1:

1 mol - 6.02×10²³ molecules

x mol - 8.022×10²⁵ molecules

$x = \frac{1 \times 8.022 \times 10^{25}}{6.02 \times 10^{23}} \\ = 133.25 \;mol$

M(Li₂SO₄) = 109.94 g/mol

m(Li₂SO₄) $= n \times M$

$= 133.25 \times 109.94 \\ = 14649.50 \;g$

M(S) = 32.06 g/mol

Proportion 2:

109.94 – 100 %

32.06 – y

$y = \frac{32.06 \times 100}{109.94} = 29.16 \%$

Proportion 3:

14649.50 – 100 %

z – 29.16 %

$z = \frac{14649.50 \times 29.16}{100}=4271.79 \;g$

Answer: 4271.79 g