If 19.7 g of CaCl2 are present in 200 mL of aqueous solution, what is the concentration in terms of the following?
a. molarity
100 M CaCl2
b. weight/volume percent
0.1 % (w/v)
c. parts per thousand
100 ppt
d. parts per million
10E4 ppm
e. parts per billion
10E7 ppb
a)
19.7g CaCl2/111 = 0.177 moles
0.177 mol/0.200L = ?
b)
19.75g/200 mL = how much per 100, so 1/2 x 19.76 = ?
c) etc
To calculate the concentration of CaCl2 in terms of molarity (M), weight/volume percent (w/v), parts per thousand (ppt), parts per million (ppm), and parts per billion (ppb), we need to use the given information of 19.7 g of CaCl2 in 200 mL of aqueous solution.
a. Molarity (M):
Molarity is calculated by dividing the moles of solute by the volume of solution in liters. To find the molarity, we need to determine the number of moles of CaCl2.
First, we convert the given mass of CaCl2 to moles by dividing it by its molar mass.
Molar mass of CaCl2 = 40.08 g/mol (for Ca) + (2 * 35.45 g/mol) (for Cl2) = 110.98 g/mol
Number of moles of CaCl2 = 19.7 g / 110.98 g/mol
Next, convert the given volume of solution from milliliters to liters.
Volume of solution = 200 mL / 1000 mL/L = 0.2 L
Finally, divide the moles of CaCl2 by the volume of solution in liters to get the molarity:
Molarity = (19.7 g / 110.98 g/mol) / 0.2 L = 100 M CaCl2
b. Weight/volume percent (w/v):
Weight/volume percent is the mass of solute (in grams) dissolved in 100 mL of solution. To calculate w/v percent, we divide the mass of solute (CaCl2) by the volume of solution (200 mL) and multiply by 100.
Weight/volume percent = (19.7 g / 200 mL) * 100% = 0.1% (w/v)
c. Parts per thousand (ppt):
Parts per thousand is the ratio of the mass of solute to the mass of the solution, multiplied by 1000. In this case, we divide the mass of CaCl2 by the mass of the solution (which is the sum of the mass of CaCl2 and the mass of water), and multiply by 1000.
Mass of solution = 19.7 g (CaCl2) + 200 g (water) = 219.7 g
Parts per thousand = (19.7 g / 219.7 g) * 1000 = 100 ppt
d. Parts per million (ppm):
Parts per million is the ratio of the mass of solute to the mass of the solution, multiplied by 1,000,000. We divide the mass of CaCl2 by the mass of the solution and multiply by 1,000,000.
Parts per million = (19.7 g / 219.7 g) * 1,000,000 = 10E4 ppm
e. Parts per billion (ppb):
Parts per billion is the ratio of the mass of solute to the mass of the solution, multiplied by 1,000,000,000. We divide the mass of CaCl2 by the mass of the solution and multiply by 1,000,000,000.
Parts per billion = (19.7 g / 219.7 g) * 1,000,000,000 = 10E7 ppb