Lithium, is used in dry cells and storage batteries and in high temperature lubricants, it has two naturally occurring isotopes, 6li and 7li. calculate the atomic mass of lithium.

The average atomic mass of lithium is 6.9241 u.

Explanation:

Average atomic mass of an element is defined as the sum of masses of each isotope each multiplied by their natural fractional abundance.

Formula used to calculate average atomic mass follows:

....(1)

Mass of isotope = 6 u

Percentage abundance of isotope = 7.59 %

Fractional abundance of isotope = 0.0759

Mass of isotope = 7 u

Percentage abundance of isotope = 92.41%

Fractional abundance of isotope = 0.9241

Putting values in equation 1, we get:

Hence, the average atomic mass of lithium is 6.9241 u.

n2(g) + 3h2-> 2nh3(g)   this is the balanced equation

note the mole ratio between n2, h2 and nh3.   it is 1 : 3 : 2   this will be important.

moles n2 present = 28.0 g n2 x 1 mole n2/28 g = 1 mole n2 present

moles h2 present = 25.0 g h2 x 1 mole h2/2 g = 12.5 moles h2 present

based on mole ratio, n2 is limiting in this situation because there is more than enough h2 but not enough n2.

moles nh3 that can be produced = 1 mole n2 x 2 moles nh3/mole n2 = 2 moles nh3 can be produced

grams of nh3 that can be produced = 2 moles nh3 x 17 g/mole = 34 grams of nh3 can be produced

note:   the key to this problem is recognizing that n2 is limiting, and therefore limits how much nh3 can be produced.

the dependant variable is spilled water

the independent is the heat