A certain barium halide exists as the hydrated salt BaX2.2H2O, where X is the halogen. The barium content of the salt can be determined by gravimetric methods. A sample of the halide (0.2650 g) was dissolved in water (200 cm3) and excess sulfuric acid added. The mixture was then heated and held at boiling for 45 minutes. The precipitate (barium sulfate) was filtered off, washed and dried. Mass of precipitate obtained = 0.2533 g. Determine the identity of X. %3D

A chemical reaction occurred when 500 mL of 7.5 x 104M Cal2 and 100 mL of 1.7 x 105M Pb(NO3)2 solutions were mixed at 25.0°C. Ksp = 1.4 x 108 а. Write out the complete chemical reaction that occurs when the calcium iodide is mixed with lead(II)nitrate. The equation must be balanced, and the states of matter need to be shown. b. Determine whether a precipitate will form. If the temperature at which the substances were mixed was lowered to -25.0°C, do you С. think that could impact your answer given in part b? Explain your answer using your knowledge about equilibrium. Assume the volumes and concentrations were not impacted by the temperature change.

A chemistry student needs to standardize a fresh solution of sodium hydroxide. She carefully weighs out 233. mg of oxalic acid (H₂C₂O4), a diprotic acid that can be purchased inexpensively in high purity, and dissolves it in 250. mL of distilled water. The student then titrates the oxalic acid solution with her sodium hydroxide solution. When the titration reaches the equivalence point, the student finds she has used 63.2 mL of sodium hydroxide solution. Calculate the molarity of the student's sodium hydroxide solution. Be sure your answer has the correct number of significant digits.

(1) To analyze the concentration of chloroform precursors, or natural organic matter, in a drinking water sample, which of the following instruments should be used? (A) TOC analyzer (B) GC (C) AA (D) IC (2) To analyze the concentration of cadmium (Cd) in a water sample, which of the following instruments should be used? (A) TOC analyzer (B) GC (C) AA (D) LC (3) To analyze the concentration of the chlorine residual in a water sample, which of the following instruments should be used? (A) TOC analyzer (B) GC (C) AA (C) AA (D) IC (4) To identify an unknown organic compound in drinking water, which of the following instruments should be used? (A) TOC analyzer (B) GC (D) IC (E) DPD Method (C) conductivity (E) GC/MS (5) To evaluate the quality of a drinking water sample, which of the following parameters may NOT be tested? (A) TSS (B) turbidity (D) TOC (E) coliforms