Chemistry help: Problems

A sample containing 0.2784 grams of sodium chloride (NaCl) and 0.5486 grams of magnesium chloride (MgCl2). The chloride in the sample was precipitated by the addition of 47.8 mL of a silver nitrate solution. What is the concentration of the silver nitrate solution?

A sample of ore containing manganese weighed 1.2354 grams. This sample was heated in a solution of nitric acid, which dissolved the manganese ion producing manganese(III) nitrate [Mn(NO3)3]. The acidity of the solution was adjusted, and hydrogen sulfide gas was bubbled into the solution producing 0.2876 grams of manganese(III) sulfide [Mn2S3]. What is the percentage of manganese in the original sample?

A sample containing Al2O3 and Na2Cr2O7?2H2O was brought into the laboratory for analysis. The analyst heated a 2.2846 gram sample of this material to 100 °C for one hour, at which time only Al2O3 and Na2Cr2O7 remained. This mixture was found to weigh 2.2312 grams. Calculate the percent chromium in the sample

Given that the solubility product for La(IO3)3 is 1.0 x 10-11, what is the concentration of La3+ in a saturated solution of lanthanum iodate?

If a 0.100 M solution of NaOH is added to a solution containing 0.200 M Ni2+, 0.200 M Ce3+, and 0.200 M Cu2+, which metal hydroxide will precipitate first? Ksp for Ni(OH)2 = 6.0 x 10-16, Ksp for Ce(OH)3 = 6.0 x 10-22, and Ksp for Cu(OH)2 = 4.8 x 10-20.