Question

Question #a19b3

Answer 1

`"6.2 g"`

Explanation:

The balanced chemical equation that describes this reaction tells you that you need `1` mole of nitrogen gas to produce `2` moles of ammonia.

`"N"_ (2(g)) + 3"H"_ (2(g)) -> 2"NH"_ (3(g))`

So right from the start, you can use the molar mass of nitrogen gas and the molar mass of ammonia to say that every

`1 color(red)(cancel(color(black)("mole N"_2))) * "28.0134 g"/(1color(red)(cancel(color(black)("mole N"_2)))) = "28.0134 g"`

of nitrogen gas that react, the reaction produces

`2 color(red)(cancel(color(black)("moles NH"_3))) * "17.031 g"/(1color(red)(cancel(color(black)("mole NH"_3)))) = "34.062 g"`

of ammonia. So if you know that the reaction produced `"7.5 g"` of ammonia, you can use this gram ratio to determine the mass of nitrogen gas that took palce in the reaction, assuming, of course, that the reaction has a `100%` yield.

`7.5 color(red)(cancel(color(black)("g NH"_3))) * "28.0134 g N"_2/(34.062color(red)(cancel(color(black)("g NH"_3)))) = color(darkgreen)(ul(color(black)("6.2 g N"_2)))`

The answer is rounded to two sig figs.