A 2.700×10 ?2 M solution of NaCl in water is at 20.0?C. The sample was created b

Question

A 2.700×10?2M solution of NaCl in water is at 20.0?C. The sample was created by dissolving a sample of NaCl in water and then bringing the volume up to 1.000 L. It was determined that the volume of water needed to do this was 999.3 mL . The density of water at 20.0?C is 0.9982 g/mL.

Part C Calculate the concentration of the salt solution in percent by mass Express your answer to four significant figures and include the appropriate units. 2 percent by mass NaCl = Value | | Units Submit Hints My Answers Give Up Review Part Part D Express your answer as an integer to four significant figures and include the appropriate units. 2 Value Units parts per million NaCl = alue Units Submit Hints My Answers Give Up Review Part

Explanation / Answer

a) moles of NaCl in the sample = molarity of the solution*volume of the solution in litres = 0.027*1 = 0.027

Molar mass of NaCl = 58.5 g/mole

Thus, mass of NaCl = moles*molar mass = 0.027*58.5 = 1.5795 g

mass of water = volume*density = 999.3*0.9982 = 997.5 g

Thus, mas of the sample = mass of NaCl + mass of water = 999.081 g

Thus, % concentration by mass = (mass of NaCl/mass of solution)*100 = 0.158%

b) 1 ppm = mg/litres

Now, in 1 litre of solution , mass of NaCl = 1.5795 g = 1579.5 mg

Thus, ppm concentration = 1579.5

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