CHEM 1311-09P: Exam 3 Review

For the reaction: 2A + B2 → 2AB; ΔH = -50.0 kJ. Which statement is correct?

• The reaction is exothermic.

• Heat is absorbed by the reaction.

• The standard enthalpy of formation for AB is 50.0 kJ.

• The bond energy for each A–B bond is 50.0 kJ.

• The reaction is endothermic.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

A pitcher throws a baseball with a mass of 0.145 kg at a velocity of 64.2 mph (miles per hour). Calculate the kinetic energy of the baseball. (1 mi = 1.609 km)

• 7.74x10⁸ J

• 59.7 J

• 299 J

• 2.08 J

• 119 J

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

A reaction occurring in a flask releases 645 J of heat to the surroundings and the gas produced performs 450 J of work on the surroundings by pushing the piston upward. Determine ΔU.

• 1095 J

• 195 J

• -195 J

• -1095 J

• -645 J

Tags

NGSS.HS-PS3-1

How much heat is released if 25.0 g of Al(s) (26.98 g/mol) burns in excess oxygen? 4Al(s) + 3O₂(g) → 2Al₂O₃(s); ΔH°rxn = –1676 kJ/mol

• 1.61 kJ

• 1.55x10³ kJ

• 388 kJ

• 808 kJ

• 3.35 kJ

Tags

NGSS.HS-PS3-1

Emily found a metallic solid in her backpack and determined its specific heat in J/g•°C. Its mass was 129.94 g and she heated it to 100.0°C. It was placed in 100.0 g water at 25.0°C and the final temperature of the system reached 30.0°C. What was the solid?

• gold, 0.1256

• silver, 0.2386

• carbon steel, 0.5024

• zinc 0.3768

• iron, 0.4605

Tags

NGSS.HS-PS3-4

What is ΔH°rxn for the following reaction?

2H₂O₂(l) → 2H₂O(l) + O₂(g)

ΔH°f: H₂O(l) = –285.8 kJ/mol, H₂O₂(l) = –187.6 kJ/mol; O₂(g) = 0 kJ/mol

• -196.4 kJ/mol

• 98.2 kJ/mol

• -98.2 kJ/mol

• -473.4 kJ/mol

• -946.8 kJ/mol

Tags

NGSS.HS-PS3-1

NGSS.HS-PS1-4

A 17.3 mL sample of argon gas was originally at 301 K and 1.00 atm pressure. If its final volume is 10.9 mL and its final pressure is 678 torr, what is its final temperature? Use the Combined gas law.

• 22.4 K

• 5.92 K

• 273 K

• 1.28x10^5 K

• 169 K

Determine the mass of carbon dioxide gas that occupies 2.98 L at 33.0°C and 945 mm Hg. (R = 0.08206 L • atm/mol • K, 1 atm = 760 mmHg) C(12.01), O(16.00)

• 4.26 g

• 4936 g

• 6.49 g

• 0.154 g

• 62.1 g

Carbon dioxide gas was collected under water in a graduated cylinder at a temperature of 24.0°C. Use the table to determine the pressure of dry carbon dioxide if the barometric pressure equals 759.50 torr.

• 737.1 torr

• 760 torr

• 759.50 torr

• 22.4 torr

• 781.9 torr

Boyle’s law states that the pressure and volume of a sample of gas are directly proportional.

• True

• False

• There is not enough information to determine