Midterm Reviews Part 2s
1. Explain in terms of protons, neutrons, and electrons why U-237 and U-238 are
different isotopes of Uranium.
2. The bright-line spectra for three elements and a mixture of elements is shown
below.
a. Explain in terms of both electrons and energy, how the bright line spectrum of
an element is produced.
b. Identify all the elements in the mixure.
c. State the total number of valence electrons in a cadmium atom in the ground
state.
3. The balanced equation below represents the decomposition of potassium
chlorate.
___KClO3(s)  ___KCl(s) + ___O2(g)
a. Determine the oxidation number of chlorine in the reactant in the equation.
b. List the coefficients in order of the chemical equation that would balance the
reaction above.
c. Identify the type of bonding between the atoms in an oxygen molecule.
d. Explain, in terms of electron configuration, why an oxygen molecule is more
stable than an oxygen atom.
4. In 1864, the Solvay process was developed to make soda ash. One step in the
process is represented by the balanced equation below.
NaCl + NH3 + CO2 + H2O  NaHCO3 + NH4Cl
a. Write the chemical formula for one compound in the equation that contains both
ionic bonds and covalent bonds.
b. Explain, in terms of electronegativity difference, why the bond between
hydrogen and oxygen in a water molecule is more polar than the bond between
hydrogen and nitrogen in an ammonia molecule.
c. Draw a Lewis electron-dot diagram for the reactant containing nitrogen in the
equation.
5. A student prepared two mixtures, each in a labeled beaker. Enough water at 20
degrees Celsius was used to make 100 milliliters of each mixture.
a. Classify each mixture using the term “homogeneous” or the term
“heterogeneous.”
b. Determine the volume of Fe filings used to produce mixture 2.
c. Describe a procedure to physically remove water from mixture 1.
6. Explain, in terms of activity why HCl(aq) reacts with Zn(s), but HCl(aq) does not
react with Cu(s).
7. Copper has two naturally occurring isotopes Information about the two isotopes
is shown below.
a. Show a numerical set up for calculating the atomic mass of copper.
b. Explain why the atomic mass of copper will be closest to 63 amu.
8. In an experiment, 2.54 grams of copper completely reacts with sulfur,
producing 3.18 grams of copper (I) sulfide.
a. Determine the total mass of sulfur consumed.
b. Write the chemical formula of the compound produced.
c. What is the percent composition of copper in the product of the reaction above.
9. A tablet of one antacid contains citric acid, H3C6H5O7, and sodium hydrogen
carbonate, NaHCO3. When the tablet dissolves in water, bubbles of CO2 are
produced. This reaction I represented by the incomplete equation below.
H3C6H5O7 + 2 NaHCO3  Na3C6H5O7 + 3CO2 + 3________
a. Complete the equation by writing the formula of the missing product.
b. State evidence that a chemical reaction occurred when the tablet was placed in
water.
c. Determine the number of moles of sodium hydrogen carbonate that will
completely react with 0.010 mole of citric acid.
10. Cold packs are used to treat minor injuries. Some cold packs contain
NH4NO3(s) and a small packet of water at room temperature before activation. To
activate this type of cold pack, the mall packet must be broken to mix the water
and NH4NO3(s). The temperature of this mixture decreases to approximately 2
degrees Celsius and remains at this temperature for 10 to 15 minutes.
a. State the direction of heat flow that occurs when the activated cold pack is
applied to the body.
b. Identify both types of bonds in NH4NO3(s)
c. Identify the type of mixture formed when the NH4NO3(s) is completely
dissolved in the water.
11. Glycine, NH2CH2COOH, is an organic compound found in proteins. Acetamide,
CH3CONH2, is an organic compound that is an excellent solvent. Both glycine and
acetamide consist of the same four elements, but the compounds have different
functional groups.
a. Calculate the gram-formula mass of glycine. Your response must include both a
numerical setup and the calculated result
b. Given the balanced equation representing a reaction:
2C2H6 + 7O2 → 4CO2 + 6H2O
Determine the total number of moles of oxygen that react completely with 8.0
moles of C2H6.
12. Answer the following questions regarding elements in Group 2 of the Periodic
Table.
a. State the general trend in first ionization energy for the elements in Group 2 as
these elements are considered in order from top to bottom in the group.
b. State, in terms of the number of electron shells, why the radius of a strontium
atom in the ground state is larger than the radius of a magnesium atom in the
ground state.
c. Explain, in terms of atomic structure, why the elements in Group 2 have similar
chemical properties.