Water treatment plants commonly use chlorination to destroy bacteria. a byproduct is chloroform (chcl3), a suspected carcinogen produced when hocl, formed by the reaction of cl2 and water, reacts with dissolved organic matter. the united states, canada, and the world health organization have set a limit of 100. ppb of chcl3 in drinking water. convert this concentration into molarity, molality, mole fraction, and mass percent. enter your answers in scientific notation.

100. ppb of chcl3 in drinking water means  100 g of CHCl3 in 1,000,0000,000 g of water

Molarity, M

M = number of moles of solute / volume of solution in liters

number of moles of solute = mass of CHCl3 / molar mass of CHCl3

molar mass of CHCl3 = 119.37 g/mol

number of moles of solute = 100 g / 119.37 g/mol = 0.838 mol

using density of water = 1 g/ ml => 1,000,000,000 g = 1,000,000 liters

M = 0.838 / 1,000,000 = 8.38 * 10^ - 7 M < answer

Molality, m

m = number of moles of solute / kg of solvent

number of moles of solute = 0.838

kg of solvent = kg of water = 1,000,000 kg

m = 0.838 moles / 1,000,000 kg = 8.38 * 10^ - 7 m < answer

mole fraction of solute, X solute

X solute = number of moles of solute / number of moles of solution

number of moles of solute = 0.838

number of moles of solution = number of moles of solute + number of moles of solvent

number of moles of solvent = mass of water / molar mass of water = 1,000,000,000 g / 18.01528 g/mol = 55,508,435 moles

number of moles of solution = 0.838 moles + 55,508,435 moles = 55,508,436 moles

X solute = 0.838 / 55,508,435 = 1.51 * 10 ^ - 8 < answer

mass percent, %

% = (mass of solute / mass of solution) * 100 = (100g / 1,000,000,100 g) * 100 =

% = 10 ^ - 6 % < answer

Molarity :M =  8.368.10⁻⁷

molality = 8.368.10⁻⁷

mole fraction  = 1.508 .10⁻⁸

mass percent = 10⁻⁵%

Further explanation

The concentration of a substance can be expressed in several quantities such as moles, percent (%) weight/volume,), molarity, molality, parts per million (ppm) or mole fraction. Concentration shows the amount of solute in a unit of the amount of solvent.

Molality (m)

Molality shows how many moles are dissolved in every 1000 grams of solvent.

 

m = Molality

n = number of moles of solute

p = solvent mass (1000 grams)

Mole

Mole itself is the number of particles contained in a substance

amounting to 6.02.10 ^ 23

Mole can also be sought if the amount of substance mass and its molar mass is known

Molarity (M)

Molarity is a way to express the density of the solution

Molarity shows the number of moles of solute in every 1 liter of solute or mmol in each ml of solution

Where

M = Molarity

n = Number of moles of solute

V = Volume of solution

ppb mean : part per billion or 1 : 10⁹, the convertion are :

1. molarity

1 ppm = 1 mg/l

1 ppm = 1000 ppb

1 ppb = 10⁻³ mg/l

100 ppb = 0.1 mg/l = 10⁻⁴ g/l

molar mass CHCl₃ = 12 + 1 + 35.5 .3 = 119.5 grams/mole

mole CHCl₃ = mass : molar mass

mole CHCl₃ = 10⁻⁴ g : 119.5

mole CHCl₃ = 8.368.10⁻⁷

Because the water(solvent) = 1 L, so the molarity :

M = mol : L

M = 8.368.10⁻⁷ : 1 L

M =  8.368.10⁻⁷

2. molality

mole CHCl₃ = 8.368.10⁻⁷

Solvent = 1 L = 1 Kg(ρ water = 1 g/ml or 1 kg/L)

molality = mole : 1 kg solvent

molality = 8.368.10⁻⁷  : 1

molality = 8.368.10⁻⁷

3. mole fraction

mole water = 1000 gr : 18 (molar mass H₂O)

mole water = 55.5

mole fraction = mole CHCl₃ : (mole H₂O + mole CHCl₃)

mole CHCl₃ is considered very small, then

mole fraction = mole CHCl₃ : mole H₂O

mole fraction = 8.368.10⁻⁷ : 55.5

mole fraction  = 1.508 .10⁻⁸

4. mass percent

mass CHCl₃ = 10⁻⁴ grams

mass H₂O = 1000 grams

mass percent = mass CHCl₃ : (mass CHCl₃+mass H₂O) x 100%

mass CHCl₃ is considered very small, then

mass percent = (mass CHCl₃ : mass H₂O)x 100%

mass percent = 10⁻⁴  : 10³ x 100%

mass percent = 10⁻⁵%

Learn more

the molality of the solution

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the difference between molarity and molality

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Keywords: molality, molarity, mass percent, mole fraction

Perimeter? wheres the answers

The answer is d.potassium