Chemistry Mid-term Exam
Directions: It is important that you provide answers in your own words. Please focus only on
information from the text/eBook to create your own solutions. Please do not use direct
information from an outside source (especially copying and pasting from an “answer” website).
Use of direct information from an outside source is against school policy. All answers will be
checked for plagiarism. Instances of plagiarism can result in probation or possible dismissal
from the school.
Please be sure to follow all guidelines (number of sentences/showing all calculations) and to
provide the correct metric units of measure. All questions are 3.33 points (.33 point for units).
1. Experimental Design: From the work you have done this semester, choose a topic and
design an experiment you would be able to perform. In your design (1) state your
hypothesis, (2) identify your dependent and (3) independent variables, (4) your control
conditions and (5) describe your experimental procedure. You do NOT have to actually
complete the experiment, just describe it with the application of the terms above.
2. Perform this operation and report the answer to the correct number of significant
figures: What is the mass of a cube of aluminum that is 4.0 cm on each edge? The
density of aluminum is 2.7 g/cm3. Show all calculations leading to an answer.
3. Explain why a model of the atom is crucial to understanding chemistry and in explaining
the behavior of matter. Use 3 - 4 sentences in your explanation.
4. What parts of Dalton’s atomic theory no longer agree with the current picture of the
current picture of the atom? Provide an answer using at least 3 to 4 complete content
related sentences in your own words.
5. If an element has 12 protons and 17 neutrons, how many electrons must it have?
6. Why are the atomic masses of elements usually decimal numbers? Provide an answer
using 3 – 4 sentences in your own words.
7. In 3 – 4 sentences and in your own words describe how Mendeleev’s periodic table
differs from Moseley’s.
8. What is the electron configuration of the element with 27 protons?
9. How many electrons are in the highest energy orbital of the element copper?
10. How many dots should be indicated in the electron dot structure of arsenic?
11. Why is the first ionization energy of a nonmetal much higher than that of an alkali metal
in its same period? Provide an answer using 3 – 4 sentences in your own words.
12. Why do compounds with strong intermolecular attractive forces have higher boiling
points than compounds with weak intermolecular attractive forces? Provide an answer
using 3 – 4 sentences and in your own words.
13. Write the formula for iron (III) sulfate.
14. What is the reason the group 13 metals have a typical charge of 3+?
15. Why does one mole of carbon atoms have a smaller mass than one mole of sulfur
16. What is the percentage of nitrogen in N2O? Show all calculations leading to an answer.
17. How many non-bonding electrons does phosphorus have?
18. Complete and balance this reaction: sulfuric acid reacts with barium chloride
19. Identify the precipitate in this reaction: calcium nitrate reacts with sodium phosphate.
20. The following is a Limiting Reactant problem:
Magnesium nitride is formed in the reaction of magnesium metal with nitrogen gas in
this reaction: 3 Mg(s) + N2(g) → Mg3N2(s)
How many grams of product are formed from 2.0 mol of N2 (g) and 8.0 mol of Mg(s)?
Show all calculations leading to an answer.
21. List 3 indicators of a chemical change.
22. Check the following problem for errors. If you find an error, identify it, tell why it is an error and
correct the error solving the problem correctly. Convert 0.45 g zinc hydroxide to moles. (Hint:
there are errors)
0.65 g ZnOH
= 3.22 X 10 25 mol
23. What is an ion? Explain how ions form. Distinguish between a cation and an anion. Be sure to
use at least 3 to 4 complete content related sentences in your explanation.
24. Write the symbol for the ion formed when each element gains electrons and attains a noble-gas
25. Name each of the compounds. There are ionic, covalent and acid/base compounds in the list.
26. Classify each chemical equation as a combination/synthesis , decomposition, single
replacement, double replacement, or combustion.
a. Pb(s) + Hg2SO4(s) → PbSO4(s) +2 Hg(l)
NaCl(aq) + AgNO3(aq) → AgCl(s) + NaNO3(aq)
c. 2 H20(l)→2 H2(g) + 02(g)
27. Find the molar mass of nitric acid (HNO3).
28. Avogadro’s number refers to ___.
a. the maximum number of electrons that all of an atom’s energy levels can
b. the number of protons and neutrons that can fit in the shells of an atom’s nucleus
c. the number of particles in one mole of a substance
d. the number of particles in exactly 1.0 g of a substance
29. How many moles of oxygen atoms are in 1.5 moles of CO2? (Sc2c)
a. 1 mol
b. 1.5 mol
30. What is the mass of 0.28 mol of iron ?
c. 2 mol
d. 3 mol
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