Assignment: Percent, ppm and ppb
1) Calculate the concentration of salt in a solution of water in percent if 45 grams is dissolved in 1,200 ml of water.
Solution:
1200ml contain 45 g
1 ml contain 45/1200
100 ml contain 45 x100/1200
2) Calculate the mass of solute in a 10% salt solution if the mass of the solvent is 350 grams.
Solution :
Suppose the mass of solute is "X"
then the mas of solution is equal 350 + X
we Know that
% of solution = mass of solute ÷mass of solution x 100
10 %= X ÷( 350+X) x 100
10 ÷ 100 = X ÷(350 +X)
0.1=X÷(350 +X)
X = 0.1(350 +X)
X= 35.0 +0.1X
X-0.1X = 35.0
0.9X = 35.0
X =35.0 ÷0.9
X= 38.88
3) Calculate the mass of solvent in a 6 ppm solution of a drug if the mass of the solute is 0.050 milligrams.
Solution:
we know that
ppm =mass of sloute ÷ mass of solvent x 106
6ppm = 0.050 mg ÷mass of solvent x106
mass of solvent= 6ppm ÷106 x 0.050mg
4) What is the concentration in ppm of selenium if 1.3 milligrams is found in 2,500 kg of soil?
Solution:
ppm = 1.3 mg ÷ 2.5 x109 mg x 106
5.2
x10-2 ppm
5) What is the concentration in ppb of PCB's in a chemical spill, if their is 0.060 mg in 4,600 Kg of soil?
Solution:
100 ml solution contain = 35 g of hydrogen peroxide
1ml solution contain = 35 ÷ 100
450 ml solution contain = 0.35 x 450 ml
7) Calculate the mass of solute PCB's in a 65 Kg person, if the concentration is 4 PPM?
Solution :
ppm = mass of sloute ÷ mass of solvent x 106
4 ppm = mass of solute ÷ 65 kg x 106
mass of sloute = 4 ÷ (65 kg x 106)
8) What mass of nickel is in a 2.4 Kg sample of propanol if the
concentration is 20 ppb?
Solution :
concentration is 20 ppb?
Solution :
9) Calculate the mass of solvent that would contain 3.0 mg of a drug if the concentration was 3.5%.
Solution:
Solution:
10) Calculate the concentration in ppm if 8 grams of CaCl2 is dissolved in 250 ml of water.
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