A chemist prepares a solution by adding 380 mg of CoCl2 (MW = 129.84 g/mol ) to
ID: 1004710 • Letter: A
Question
A chemist prepares a solution by adding 380 mg of CoCl2 (MW = 129.84 g/mol ) to a volumetric flask, and then adding water until the total volume of the contents of the flask reaches the calibration line that indicates 100 mL . Determine the molarity of the prepared solution. Express the concentration in moles per liter to three significant figures.
Determine the mass of chloride (MW = 35.45 g/mol ) in grams present in 100 mL of a 0.219 M solution of aqueous TiCl3 (titanium(III) chloride) Express the mass in grams to three significant figures.
A beaker contains 347 mL of a 5.75 M HCl(aq) solution. Determine the new concentration of the solution after it is diluted by adding 110 mL of water.
Express the concentration in molarity to three significant figure
Explanation / Answer
1) Molarity = w/Mwt*1000/V in ml
Molarity = (0.38/129.84)*(1000/100) = 0.0293 M
2) No of mol of Cl- = 3*0.1*0.219 = 0.0657 mol
mass of cl- = 0.0657*35.45 = 2.33 grams
3) M1V1= M2V2
347*5.75 = (347+110)*M2
M2 = final molarity = 4.37 M
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