A chemist must prepare 850.0 mL of potassium hydroxide solution with a pH of 12.60 at 25 °C. She will do this in three steps: • Fill a 850.0 mL volumetric flask about halfway with distilled water. • Weigh out a small amount of solid potassium hydroxide and add it to the flask. . Fill the flask to the mark with distilled water. Calculate the mass of potassium hydroxide that the chemist must weigh out in the second step. Round your answer to 2 significant digits. 6.0 0x10 X Ś ?

Rate data have been determined at a particular temperature for the overall reaction 2NO + 2H2 → N2 + 2H2O in which all reactants and products are gases. Trial Run Initial [NO] Initial [H 2] Initial Rate ( M•s1) 1 0.10 M 0.20 M 0.0150 2 0.10 M 0.30 M 0.0225 3 0.20 M 0.20 M 0.0600 What would be the initial rate of the reaction if the initial molar concentration of NO = 0.30 M and the initial molar concentration of H 2 = 0.10 M? О а. 0.068 Мes-1 O b.0.10 Mos-1 O c. 0.040 M•s-1 O d. 0.022 Mos-1 O e. 0.22 Mos-1

A chemist dissolves 158. mg of pure potassium hydroxide in enough water to make up 130. mL of solution, Calculate the pH of the solution. (The temperature of the solution is 25 °C.) Round your answer to 3 significant decimal places.

A chemist dissolves 815. mg of pure barium hydroxide in enough water to make up 110. mL of solution. Calculate the pH of the solution. (The temperature of the solution is 25 °C.) Be sure your answer has the correct number of significant digits. 0 x10 ×

A chemist must prepare 800.0 mL of potassium hydroxide solution with a pH of 12.90 at 25 °C. She will do this in three steps: • Fill a 800.0 mL volumetric flask about halfway with distilled water. Weigh out a small amount of solid potassium hydroxide and add it to the flask. • Fill the flask to the mark with distilled water. Calculate the mass of potassium hydroxide that the chemist must weigh out in the second step. Round your answer to 2 significant digits.

A chemist dissolves 204. mg of pure barium hydroxide in enough water to make up 170. mL of solution. Calculate the pH of the solution. (The temperature of the solution is 25 °C.) Round your answer to 3 significant decimal places. 0 x10 X Ś

A chemist must prepare 400.0 mL of hydrochloric acid solution with a pH of 1.20 at 25 °C. He will do this in three steps: • Fill a 400.0 mL volumetric flask about halfway with distilled water. • Measure out a small volume of concentrated (8.0M) stock hydrochloric acid solution and add it to the flask. • Fill the flask to the mark with distilled water. Calculate the volume of concentrated hydrochloric acid that the chemist must measure out in the second step. Round your answer to 2 significant digits. |mL x10

Consider the following data on some weak acids and weak bases: name hydrofluoric acid hydrocyanic acid acid 0.1 M C₂H5NHBr 0.1 M NH4CI 0.1 M NaI solution 0.1 M NaF formula HF HCN Ka 6.8 × 10 4.9 × 10 Use this data to rank the following solutions in order of increasing pH. In other words, select a '1' next to the solution that will have the lowest pH, a '2' next to the solution that will have the next lowest pH, and so on. 10 pH choose one ✓ choose one ✓ choose one ✓ base choose one ✓ name formula Kb ammonia NH3 1.8 × 10 pyridine CHN 1.7 x 10 9

A chemist dissolves 715. mg of pure sodium hydroxide in enough water to make up 110. mL of solution. Calculate the pH of the solution. (The temperature of the solution is 25 °C.) Round your answer to 3 significant decimal places.

A chemist must prepare 700.0 mL of sodium hydroxide solution with a pH of 12.30 at 25 °C. She will do this in three steps: • Fill a 700.0 mL volumetric flask about halfway with distilled water. • Weigh out a small amount of solid sodium hydroxide and add it to the flask. • Fill the flask to the mark with distilled water. Calculate the mass of sodium hydroxide that the chemist must weigh out in the second step. Round your answer to 2 significant digits. Ox10