ACS Exam Review

Topic 1: Naming Compounds

Name the following compounds:

Na3PO4Sodium Phoshpate

FeCl2Iron (II) Chloride

Write the molecule in symbol form:

Beryllium NitrideBe3N2

DinitrogenTetraoxideN2O4

Topic 2: Limiting Reactant

If 45.0 g of H2S and 50.0 g of O2 were allowed to react in the equation, how many grams of S8 could be produced? If in the lab we produced 90% yield, how much S8 would we have?

8 H2S (g) + 4 O2 (g)  S8 (l) + 8 H2O (g)

42.3 g S8 with 45 g of H2S as limiting reactant, 38.1 g with 90% yield

Topic 3: Energetics

The specific heat of aluminum is 0.90 J/g-°C. When you add 250 J of heat to 30 g of aluminum originally at room temperature (25°C), what will the final temperature be?

Tf= 34 C

Find the ΔH for the reaction

2 N2(g) + 5 O2(g) 2 N2O5(g)

Using these reactions:

2 H2(g) + O2(g) 2 H2O(l) (Ho/kJ = -571.6) reverse
N2O5(g) + H2O(l) 2 HNO3(l)(Ho/kJ = -73.7) reverse and x2
N2(g) + 3 O2(g) + H2(g) 2 HNO3(l)(Ho/kJ = -348.2) x 2

Overall= 22.6

Topic 4: Electronic Structure

What is the frequency of a radiation with a wavelength of 567 nm?

5.29 x 1014 s-1

What is the energy of a photon of electromagnetic radiation whose wavelength is 233 nm?

E= 8.53 x 10-10 J

Topic 5: Quantum Numbers

Give the following quantum numbers possible for l, ml, and ms when n=2.

n / 2
l / 0 / 1
ml / 0 / -1 / 0 / 1
ms / +.5 / -.5 / +.5 / -.5 / +.5 / -.5 / +.5 / -.5

Give the electron configuration of Mn.

[Ar]4s23d5

Topic 6: Lewis Structures

Draw the Lewis structures of the following compounds:

NH3PBr5SO3

You can google these to see if you are correct

Topic 7: Gas Law

How many grams of Helium will produce a pressure of 1.2 atm in a volume of 350 mL at 300 K?

0.068 g He

Topic 8: Kinetics

  1. For the reaction A + B AB, the following data was obtained

Trial / [A] (M) / [B] (M) / Initial Rate (M/s)
1 / 0.720 / 0.180 / 0.470
2 / 0.720 / 0.720 / 1.880
3 / 0.360 / 0.180 / 0.117

a)Determine the order for each reactant

B is 1st order

A is 2nd order

b)What is the overall order of reaction?

3rd order

c)Write the rate expression for the reaction

Rate= k[A]2[B]

d)What is the value of the rate constant, k?

K= 5.04 x 10-2 M-2 s-1

Given the following graphs, what is the order of the reaction?

1st order because ln(A) vs. Time is straight

If the equation of the linear trendline is y= -0.0002 + 6.2251, what is the value of the rate constant?

Slope= -k

K= 0.0002

What is the half-life of the reaction?

T1/2= 0.693/K

T1/2= 3465 sec

What will [A] be at t= 10,000 seconds if the original concentration was 500 M?

A= 67.7 M

The reaction below is showing ______decay. Fill in the missing element with the atomic and mass number.

Topic 9: Acids/Bases/Buffers

Name the 7 Strong Acids

What is the pH of a solution containing 0.02 M NaOH?

pH= 12.3

Find the pH of a solution containing 0.21 M Nitrous Acid (HNO2). The Ka for nitrous acid is 4.0 x 10-4.

pH= 2.04

What would the pH be if you added 0.23 mol of NaNO2 and the solution had a total volume of 1 L.

Use Henderson hasselbach

pH= 3.44

Topic 10: Thermodynamics

Calculate the standard enthalpy, entropy, and free energy of the following reaction using the formation values found in the table.

C2H4 (g) + 3 O2 (g)  2 CO2 (g)+ 2 H2O (g)

Substance / ΔG°f (kJ/mol) / ΔS°f (J/mol*K) / ΔH°f (kJ/mol)
C2H4 (g) / 68.4 / 219.5 / 52.3
O2 (g) / 0 / 205.0 / 0
CO2 (g) / -394.3 / 213.7 / -393.5
H2O (g) / -228.6 / 69.9 / -241.8

G= -1314.2 kJ

S= -267.3 J/K

H= -1322.9 kJ

If a reaction has a ΔH= 32 kJ and ΔS= 60 J, what will the ΔG be at 200 K? Is the reaction spontaneous?

-8800 J, spontaneous

Topic 11: Electrochemistry

Balance the following equation

H3AsO4(aq) + Zn(s) →AsH3(g) + Zn2+(aq) (acidic)

8H+ + H2AsO4 + 4Zn  AsH3 + 4 Zn2+ + 4 H2O

Using the half reactions, calculate the free energy of the reaction.

Al3+(aq) + 3e- Al (s) E°= -1.66 V

Au3+ + 3e-(aq)  Au (s) E°= 1.50 V

E= 3.16

G= -nFE

= (-3) (96485) (3.16)= -915000 J