Gravimetric Analysis and Chemical Reactions

In this video, Jeremy Krug wraps up unit 4 section 5 on reaction stoichiometry by solving problems involving solution stoichiometry. The video covers calculating moles of reactants, identifying the limiting reactant, and determining the concentration of nitrate ions. It also includes a graphical problem and a gravimetric analysis problem to find the percentage of chloride in a sample. The video emphasizes using stoichiometry to solve chemical problems and provides strategies for eliminating incorrect choices in graphical questions.

What is the key observation that indicates a chemical reaction has occurred between lead(II) nitrate and sodium iodide?

• Formation of a gas

• Formation of a solid precipitate

• Change in temperature

• Color change

How many moles of lead(II) nitrate are present in a 0.150 gram sample?

• 3.31 x 10^-3 moles

• 1.50 x 10^-2 moles

• 2.21 x 10^-4 moles

• 4.53 x 10^-4 moles

What is the number of moles of sodium iodide in a 125 mL solution with a concentration of 0.100 M?

• 0.0125 moles

• 0.025 moles

• 0.00125 moles

• 0.125 moles

Which reactant is the limiting reactant in the reaction between lead(II) nitrate and sodium iodide?

• Neither is limiting

• Both are limiting

• Lead(II) nitrate

• Sodium iodide

What is the molar concentration of nitrate ions after the reaction is complete?

• 1.25 x 10^-2 M

• 9.06 x 10^-4 M

• 5.00 x 10^-3 M

• 7.25 x 10^-3 M

Which diagram best represents the reaction results, considering the limiting reactant and excess reactant?

• Diagram showing excess lead ions

• Diagram showing excess iodide ions

• Diagram showing excess sodium ions

• Diagram showing no excess ions

In a gravimetric analysis, what is the purpose of adding excess silver nitrate to a chloride-containing sample?

• To neutralize the solution

• To dissolve the chloride

• To form a precipitate with chloride

• To increase the solution's volume

What is the molar mass of silver chloride used in the gravimetric analysis?

• 143.32 g/mol

• 58.44 g/mol

• 35.45 g/mol

• 107.87 g/mol

How many grams of chloride are present in a sample if 8.086 grams of silver chloride precipitate is formed?

• 2.000 grams

• 3.000 grams

• 1.500 grams

• 2.500 grams

What is the percentage of chloride in a 5.000 gram sample if 2.000 grams of chloride are present?

• 60%

• 50%

• 20%

• 40%