Naturally occurring magnesium has an atomic mass of 24.312 and consists of three isotopes. the major isotope is 24mg, natural abundance 78.99%, relative atomic mass 23.98504. the next most abundant isotope is 26mg, relative atomic mass 25.98259. the third most abundant isotope is 25mg whose natural abun- dance is in the ratio of 0.9083 to that of 26mg. find the relative atomic mass of 25mg.

Explanation:

It is known that the sum of natural abundances of all the isotopes is equal to 100.

When x is the % represented by , then 0.9083x represents % for .

Therefore,  x + y + 78.99 = 100

                    x + y = 100 - 78.99

                    x + y = 21.01%

Therefore,   x + 0.9083x + 0.7899 = 1.00             (as y = 0.9083x)

                       x = 0.1101

Hence, relative atomic mass of is calculated as follows.

           (0.7899)(23.98504) + (0.1101)(25.98259) + (0.1000)(a) = 24.312

                         18.9458 + 2.8607 + 0.1000a = 24.312

                                        0.1000a = 2.5055

                                            a = 25.055

Thus, we can conclude that the atomic mass of is 25.055.

calculate how many grams of ammonia can be produced from 4.21 grams of

n2 + 3h2 = 2nh3

my answer:

25.0g n2 x (1 mol/ 28.0gn2) x (2 mol nh3/ 1 mol n2) x (17.0g nh3/ 1 molnh3) = 30.36g n2

25.0g h2 x (1 mol h2/ 2.00g h2) x (2 mol nh3/ 3 mol h2) x (17.0g nh3/ 1 mol nh3) = 141.67g h2

lr = n2

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.