Question

Carbon disulfide, CS2 can be made from coke, C and sulfur dioxide, SO2: 3C + 2 SO2→ CS2 + CO2. If the actual yield of CS2 is 86% of the theoretical yield, what mass of coke is needed to produce 950g of CS2?

Answer 1

`523` `"g C"`

Explanation:

Since `950` `"g"` is the desired mass of `"CS"_2`, and the percent yield is `86%`, the theoretical yield of `"CS"_2` is

`950` `"g CS"_2"` `xx 100/86 = ul(1107color(white)(l)"g CS"_2`

Now, let's convert this value to moles, using the molar mass of carbon disulfide:

`1107cancel("g CS"_2)((1color(white)(l)"mol CS"_2)/(76.14cancel("g CS"_2))) = color(red)(14.5` `color(red)("mol CS"_2`

Now, we use the coefficients of the chemical equation to find the relative number of moles of `"C"`:

`color(red)(14.5)cancel(color(red)("mol CS"_2))((3color(white)(l)"mol C")/(1cancel("mol CS"_2))) = color(green)(43.5` `color(green)("mol C"`

Finally, we use the molar mass of coke (carbon) to find the mass:

`color(green)(43.5)cancel(color(green)("mol C"))((12.011color(white)(l)"g C")/(1cancel("mol C"))) = color(blue)(ul(523color(white)(l)"g C"`