WHAT IS THE CONCENTRATION, IF A SOLUTION IS PREPARED BY DISSOLVING 90ML OF HYDROGEN PEROXIDE IN ENOUGH WATER TO MAKE 3000ML OF SOLUTION

30%

Explanation:

Chemical concentrations are general defined as the ratio between amount of solute (Less amount compound, hydrogen peroxide) and amount of solvent or solution (More amount, water).

For example, volume/volume percentage -(V/V%)- is defined as 100 times the ratio between volume of solute (90mL of hydrogen peroxide) and volume of solution (300mL of solution), that is:

V/V% = 90mL / 300mL * 100 =

30%

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.