Nitrogen reacts with hydrogen to produce ammonia. Calculate the mass of ammonia made from 84.0g of nitrogen.
(1) First, write out the equation if it is not given: N2 + 3H2 ---> 2NH3 (2) Calculate the moles of nitrogen in the reaction using the information you have; in this case it is mass and relative formula mass, so we will use the equation linking these two, which is n=m/M (take M for nitrogen as 14 from the periodic table, and multiply it by 2 to give M for N2): n=84/28 n= 3 (3) Look at the equation; the ratio of nitrogen to ammonia is 1:2. Therefore we must multiply the moles of nitrogen by 2 to get the moles of ammonia produced: n= 3x2 = 6 (4) Now we know the moles of ammonia produced, and we can calculate the relative formula mass of ammonia from the periodic table: M= 14+1+1+1= 17 (5) We can use this information to calculate the mass of ammonia produced by rearranging the equation we used previously: m= nxM m= 6x17 m= 102g
