Chemical Properties and Reactions

This video walkthrough covers Part C of the August 2015 New York State Regents' Chemistry exam. It includes discussions on antimony isotopes, ammonium chloride dissolution, combustion reactions, the use of salt on icy roads, double replacement reactions, organic compounds, acid-base neutralization, and oxidation-reduction processes. Each section provides detailed explanations and calculations related to the chemistry concepts tested in the exam.

What is the percent composition by mass of Antimony in Stibnite (Sb2S3) if the gram formula mass is 340 g/mol?

• 75.0%

• 68.2%

• 71.8%

• 70.5%

How do you calculate the atomic mass of an element with isotopes having different abundances?

• Use the mass of the most abundant isotope

• Add the masses and divide by the number of isotopes

• Multiply each mass by its abundance and sum the results

• Average the masses directly

What type of bonds are present in ammonium chloride (NH4Cl)?

• Van der Waals and covalent

• Hydrogen and ionic

• Metallic and covalent

• Ionic and covalent

What happens to the temperature of water when ammonium chloride is dissolved in it?

• It fluctuates

• It remains constant

• It decreases

• It increases

What is the phase of carbon dioxide produced in the combustion of carbon?

• Solid

• Plasma

• Liquid

• Gas

Why is sodium chloride used on icy roads?

• It absorbs water

• It lowers the freezing point of water

• It raises the freezing point of water

• It reacts with ice to form a gas

Which compound is insoluble in water when lead nitrate and sodium iodide are mixed?

• Lead nitrate

• Sodium nitrate

• Lead iodide

• Sodium iodide

What class of organic compounds do molecules with a hydroxide group belong to?

• Ethers

• Alcohols

• Ketones

• Aldehydes

What happens to the pH of gastric juice when an antacid is added?

• It decreases

• It increases

• It becomes neutral

• It remains the same

What is the oxidation state change of carbon in the reaction of methane to carbon dioxide?

• From +4 to 0

• From -4 to +4

• From +4 to -4

• From 0 to +4