the molecular formula of a compound used for bleaching hair is H2O2 . calculate a) Mass of this compound that would contain 2.5 moles. b) No. of moles of this compound that would exactly weight 30 g
Answers
Answer:
In its pure form, hydrogen peroxide is a pale blue, clear liquid slightly more viscous than water. Apart from various other uses, it is an ingredient that is included in most commercial hair dyes and available at low concentrations (3%). Assume that the concentration is expressed in weight percent…3% w/w. So, 3% w/w of H2O2 solution = 3 g pure H2O2/ 100 g of solution. Since it is a dilute solution, the density approximately equals to 1 g/mL. Then, 3% w/w H2O2 contain 3 g of pure H2O2 and 97 g or 97 mL of water.
Here, in 2.5 moles H2O2, the amount of H2O2 is 2.5 moles x molar mass (34 g/mole) or 85 g ‘pure’ H2O2.
Hence, the mass of H2O2 containing 85 g of pure H2O2 = (85 g/3 g) x 100 mL of 3 % of H2O2 solution.
The mass of 3 % w/w H2O2 solution that would contain 2.5 moles H2O2 = 2,833.33 g or 2.83 kg ~ 2.83 L.
To calculate the mole for exact weight 30 g of 'pure' H2O2 :
(30 g/85 g) x 2.5 moles = 0.88 mole 'pure' H2O2 solution.
Answer:
1 mole of H2O2 = 1×2+16×2
= 34g
2.5 moles. =. 34 g × 2.5
=. 85 g
Explanation:
determinant ne its molar mass and use it to convert moles to mass in grams