NC Chemistry Comprehensive Exam

This balanced equation represents a chemical reaction using palladium, Pd, as a catalyst.

CO₂ (g) + H₂O (l) → H₂CO₃ (l)

Without palladium the reaction is slow and produces low concentrations of product. How does the palladium increase the speed of the reaction?

• The palladium reacts with the water.

• The palladium lowers the activiation energy

• The palladium purifies the carbon dioxide.

• The palladium increases the reaction temperature.

Tags

NGSS.HS-PS1-4

Neutralization occurs when 15.0 mL of KOH react with 25.0 mL of HNO₃. If the molarity of HNO₃ is 0.750 M, what is the molarity of the KOH?

• 1.67 M

• 1.25 M

• 0.600 M

• 0.450 M

What is the molarity of 28.9 g of CaCl₂ dissolved in water to make 0.78 L of solution?

• 0.33 M

• 0.69 M

• 1.5 M

• 3.0 M

What is the [H⁺] of an HCl solution of the pH is measured to be 6?

• 1x10^-7 M

• 1x10^-6 M

• 6x10^-6 M

• 8x10^-3 M

When combined, two gases have a pressure of 4.0 atm. If one gas has a pressure of 1.5 atm, what is the pressure of the second gas?

• 1.5 atm

• 2.0 atim

• 2.5 atm

• 5.5 atm

What is the best reason for using iron filings instead of an iron nail in a chemical reaction?

• to decrease the amount of catalyst during the reaction

• to increase the molecular structure during the reaction

• to decrease the rate of the reaction

• to increase the surface area of the reaction

Using the solubility graph provided, a student performs an experiment to find the solubility of a substance. The student finds the amount of substance needed to make a saturated solution in 100 g of water at different temperatures. The student's data are shown in the table below the graph.

What is the identity of the substance?

• sodium nitrate

• potassium nitrate

• sodium chloride

• potassium chlorate

Tags

NGSS.HS-PS1-5

Which will increase the solubility of most solid solutes?

• decreasing the temperature

• decreasing the amount of solvent at constant temperature

• increasing the amount of solute at constant temperature

• increasing the temperature

What happens to the pressure of a constant mass of gas at constant temperature when the volume is doubled?

• The pressure is doubled.

• The pressure remains the same.

• The pressure is reduced by 1/2.

• The pressure is reduced by 1/4.

The total pressure in a closed vessel containing N₂, O₂, and CO₂ is 30 atm. If the partial pressure of N₂ is 4 atm and the partial pressure of O₂ is 6 atm, what is the partial pressure of CO₂?

• 20 atm

• 30 atm

• 40 atm

• 50 atm