Precipitation reactions

Question

The mass% of Cl- in seawater sample is determined by titrating 25.00mL of seawater with AgNO3 solution, causing a precipitation reaction. An indicator is used to detect the end point, which occurs when free Ag+ ion is present in solution after all the Cl- has reacted. If 53.63mL of 0.2960M AgNO3 is required to reach the end point, what is the mass percent of Cl- in the seawater (d of seawater = 1.024g/mL)?

I tried many ways, but couldnt find the right answer, somebody pls help me and show how you do it, via youtube video for example?

A lot of thanks!

Answer 1

Start with an amount of AgNO₃ solution and go to mass of chloride ions:

53.63 ml soln(1L/1000 mL)(.296 moles Ag⁺/L)(1Cl^-/Ag⁺)(35.45 g/mole Cl^-) = .56275 g of Cl^-

In order to find mass percent of Cl^- we need the mass of seawater:

25.00 ml Sea water (1.024 g/ml SW) = 25.60 g of SW

Now take (m_Cl/m_SW) x 100

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