A 0.693g of sample of a silver alloy used to make cutlery is dissolved completely in nitric acid. Excess sodium chloride solution is added to produce a precipitate of silver chloride. The precipitate is filtered, dried and found to weigh 0.169g.

a) find the percentage of silver in the alloy.
b) if the precipitate was not completely dry when weighed, what effect would this have on the answer for part a?

1. 0.693 g is the amount of a silver alloy that you used.

2. Silver chloride was generated from that -- exactly 0.169 grams.

3. Find the molecular weight of AgCl (silver chloride) and divide that into the weight of silver chloride that was generated. That gives you the number of moles of AgCl that were produced.

4. The equation for the reaction is

AgNO3 + NaCl = AgCl + NaNO3.

5. From the equation, determine how many moles of AgCl are produced from 1 mole of Ag.

6. From the answer in #5, multiply the number of moles of Ag by the atomic weight of Ag to get the number of grams of Ag you started with.

7. Divide the answer from #5 by the weight of the sample (0.693 g) and multiply by 100 to get the percentage.