Name: Regents Chemistry Review Packet B2

1. Determine the volume of 2.00 M HCl(aq) solution required to completely neutralize 20.0 milliliters of 1.00 M NaOH(aq) solution.

2. Determine the mass of that dissolves in 100. grams of water at to produce a saturated solution.

3. State, in terms of molecular polarity, why ethanol is soluble in water.

Base your answers to questions 4 through 6 on the information below and on your knowledge of chemistry.

Three elements, represented by D, E, and Q, are located in 3. Some properties of these elements are listed in the table below. A student's experimental result indicates that the density of element Q is , at room temperature and standard pressure.

4. Identify the physical property in the table that could be used to differentiate the samples of the three elements from each other.

5. Identify the on the Periodic Table to which element D belongs. 6. Determine the percent error between the student's experimental density and the accepted density of element Q.

Base your answers to questions 7 through 9 on the information below and on your knowledge of chemistry.

The equation below represents an equilibrium system of . The reaction can be catalyzed by or .

7. Compare the rates of the forward and reverse reactions at equilibrium.

8. State how the equilibrium shifts when is removed from the system.

9. potential energy diagram for the forward reaction is shown above. On this diagram, draw a dashed line to show how the potential energy changes when the reaction occurs by the catalyzed pathway. Base your answers to questions 10 and 11 on the information below and on your knowledge of chemistry.

The formulas for two compounds are shown below.

10. Explain, in terms of bonding, why compound A is saturated.

11. Explain, in terms of molecular structure, why the chemical properties of compound A are different from the chemical properties of compound B.

Base your answers to questions 12 through 15 on the information below and on your knowledge of chemistry.

Some of are K-37, K-39, K-40, K-41, and K-42. The and the for the naturally occurring isotopes of potassium are shown in the table below.

12. Identify the decay mode of K-37. 13. Complete the nuclear equation below for the decay of K-40 by writing a notation for the missing .

14. Determine the fraction of an original sample of K-42 that remains unchanged after 24.72 hours.

15. Show a numerical setup for calculating the atomic mass of potassium.

Base your answers to questions 16 through 18 on the information below and on your knowledge of chemistry.

The Bohr model of the atom was developed in the early part of the twentieth century. A diagram of the Bohr model for one atom, in the ground state, of a specific element, is shown below. The nucleus of this atom contains 4 protons and 5 neutrons.

16. State the atomic number and the mass number of this element.

Atomic number:

Mass number: 17. State the number of electrons in each shell in this atom in the ground state.

Number of electrons in first shell:

Number of electrons in second shell:

18. Using the Bohr model, describe the changes in electron energy and electron location when an atom changes from the ground state to an excited state. Answer Key Regents Review Packet B2

1. 10.0 mL 10. All the 15. -to-carbon /(93.26%)(38.96 u) 2. 64 g or any value + (0.01%)(39.96 u) from 62 g to 66 g bonds are single bonds. + (6.73%)(40.96 3. Both ethanol The maximum u)/(0.9326)(38.96) + molecules and water number of H atoms (0.0673)(40.96) + molecules are polar. are bonded to the (0.0001)(39.96) Water molecules carbon chain. 16. Atomic Number: 4 and ethanol There are no Mass Number: 9 molecules have multiple bonds. similar polarity. 17. Number of electrons 11. —A molecule of in first shell: 4. density compound B has an 5. Group 1/alkali organic acid Number of electrons metals functional group and in second shell: a molecule of 6. 5.0% compound A has no 18. Change in electron 7. At equilibrium, the functional group. energy: —Electron rates of the forward —A molecule of A energy increases. and reverse has only single —An electron reactions are equal. bonds and a absorbs energy. The rates are the molecule of B has —more energy same. one double-bonded 8. The equilibrium will atom. —A Change in electron shift to favor the molecule of location: —An formation of . compound B has two electron moves to a The rate of the O atoms and a higher electron shell. forward reaction is molecule of —from the first to greater than the rate compound A has no the second of the reverse O atoms in its shell—second to reaction. structure. —A is a higher energy level The equilibrium will hydrocarbon but B is —farther from the shift to favor the an acid. —A is an nucleus forward reaction. alkane but B is an The equilibrium will acid. shift to the right. 12. positron decay/ / The concentrations of the reactants will decrease. 13. , Ca-40, -40 9. 14. , 25%, 0.25