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Midterm Diagnostic

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Midterm Diagnostic (125 pts) Name:

1. Identify the picture shown here as a chemical change or a physical change. Explain your response. (2 pts)

Chemical; the bonds have changed

2. Examine the diagram below.

rectangle 1

a. What state of matter is this mixture in? ___Gas_________ (1 pt)

b. Is the mixture homogeneous or heterogeneous? ___heterogeneous_______ (1 pt)
c. Which of the following describes this mixture best? (1 pt)

i. two elements

ii. an atomic element and a compound

iii. a molecular element and a compound

iv. two molecular elements

v. two compounds

d. The two substances have the following properties:

Density = 2.04 g/mL, Particle size = 320 pm, Boiling point = 18oC
Density = 2.75 g/mL, Particle size = 502 pm, Boiling point = 19oC

Based on this information, what is probably not a good method to separate this mixture? Explain. (2 pts)

Distillation; the boiling points are too similar

3. The following is a diagram of a caffeine molecule. Write its chemical formula. (2 pts)


4. Report the length of the bar shown below to the proper number of sig figs.

Bar length = ___28________ cm (2 pts)

4. Count the number of significant figures in each of the following measurements.
a. 6.07 cm (1 pt ea) 3 sig figs

b. 13.100 kg 5 sig figs

c. 2300 L 2 sig figs

d. 0.0040700 g 5 sig figs

e. 62,500 m 3 sig figs

5. Perform the following calculations and round them to the appropriate value, taking significant figures into account. (2 pt ea)
a. 5.640 + 1.2 = 6.8

b. 3.3 x 3.17 = 10.

c. 1200/4.51 = 270
6. The pressure that the atmosphere exerts at sea level is 14.7 lbs/in2. Convert this value to N/m2. Use the following conversions factors and other metric conversions to solve. Use must use the double fenceposting method. (6 pts)

2.54 cm = 1 in 1 lb = 4.45 N

1.01 x 105 N/m2

7. Automobile batteries are filled with an aqueous solution of sulfuric acid. What is the mass of the acid (in grams) in 500. mL of the battery acid solution if the density of the solution is 1.285 g/cm3 and if the solution is 38.08% sulfuric acid by mass?

(4 pts)
245 grams of acid

8. A jar contains 1437 jellybeans of various flavors. Marco and Jasmine each attempt to count how many there are. To be sure, they each count 3 times and record the following data:

  1. Discuss Marco’s results in terms of accuracy and precision. (1 pt)

Marco’s results are accurate but not very precise.

  1. Marco:







    Discuss Jasmine’s results in terms of accuracy and precision. (1 pt)

Jasmine’s results are very precise, but not accurate.

  1. Discuss each person’s results using the terms random error and systematic error. (1 pt)

Marco encountered random error because it was minimized by multiple trials. Jasmine’s error was systematic because it was not minimized by multiple trials.

9. Fill in the following chart. It contains both ionic and molecular compounds.

(1 pt ea)


Chemical Formula

Dinitrogen hexoxide


Copper(I) carbonate


Lead(IV) sulfate


Tetraphosphorous decaoxide


10. Air is about 76.7% N2 gas and 23.3% O2 gas by mass. You take a breath and inhale 0.65 g of air. Using a single fencepost for each, calculate:

a. The number of moles of N2 inhaled (2 pts)

0.0178 moles N2

b. The number of molecules of O2 inhaled (2 pts)

2.85 x 1021 molecules O2

c. The total number of atoms inhaled (you may use two fenceposts) (2 pts)

2.71 x 1022 total atoms
11. Balance the equations with the lowest possible whole number ratios: (3 pts ea)
a. 3Ca(NO3)2 + 2K3PO4  Ca3(PO4)2 + 6KNO3
b. 2 C4H10 + 13 O2  8 CO2 + 10 H2O
12. The ginger root extract galanganol A contains 71.97% carbon, 6.72% hydrogen, and 21.31% oxygen. Its molar mass is around 300 g/mol.

a. Calculate its empirical formula. Show your work. (6 pts)

b. Calculate its molecular formula. Show your work. (2 pts)


13. 50.0 g of N2 and 150 g of H2 are combined and allowed to react according to the following equation.
N2(g) + 3 H2(g)  2 NH3(g)

  1. What is the limiting reagent? Show your work. (4 pts)

The limiting reagent is __N2________ .

  1. When the reaction is complete, how many grams of all chemicals will there be? You must solve with an ICE chart. (6 pts)

___0___ g N2

__139.2___ g H2

__60.8__ g NH3

14. An unknown fuel, C3Hx, is burned according to the following unbalanced equation:
C3Hx (l) + O2 (g)  CO2 (g) + H2O (g)

If 22 g of the fuel is burned, 36 g of H2O is produced. Determine the formula of the fuel. (4 pts)

X = 8; the formula is C3H8
15. a. Write a balanced chemical equation for the reaction that takes place when lead(II) nitrate reacts with aluminum chloride. (3 pts)
3Pb(NO3)2 + 2AlCl3  2Al(NO3)3 + 3PbCl2

  1. What type of reaction is this? _____Double Replacement____________ (1 pt)

16. Magnesium has three natural isotopes, Mg-24, Mg-25, and Mg-26, as shown in the table below:


Mass of Isotope

Percent abundance










The average atomic mass of magnesium is 24.31. Calculate the % abundance of Mg-24 and Mg-26. (2 pts ea)

17. Determine the number of protons, neutrons, and electrons for the following atoms. If no charge is listed, assume the atom is neutral. (1 pt ea)
a. 29p, 34n, 29e d. Uranium-235 92p, 143n, 92e

b. 26p, 29n, 23e e. 7p, 8n, 10e
c. Bromine-79 35p, 44n, 35e f. Hydrogen-3 1p, 2n, 1e

18. a. Element #114, formerly known as ununquadium (Uuq), was recently given the name Flerovium (Fl). One method to successfully produce the Fl-290 isotope is to bombard plutonium-242 with another particle (no other products are made in the reaction). Write the full nuclear equation for this reaction. (2 pts)
242Pu94 + 48Ca20290Fl114
b. Once produced, Fl-290 is not very stable. Write the full equation for the first step of its predicted decay. (2 pts)

290Fl1144α2 + 286Cn112 (Cn may be Uub on your table)
19. Another recently named element is #116, formerly ununhexium (Uuh). Now called Livermorium (Lv), its most stable isotope is Lv-293, with a half-life of 61 milliseconds. If you somehow managed to obtain 100 grams of this material (basically impossible), how much would remain after a second? (4 pts)
0.0012 grams

20. Consider the following nuclear reaction:

Which has a larger mass: the products, or the reactants?

Explain your answer. (3 pts)

The reaction releases energy, so mass is lost. So the reactants have more mass

21. Write the full electron configuration for the following atoms/ions: (2 pts ea)

  1. As 1s22s22p63s23p64s23d104p3

b. Br1- 1s22s22p63s23p64s23d104p6

22. Write the abbreviated electron configuration for the following: (2 pts ea)

  1. Bi [Xe]6s24f145d106p3

b. Cu2+ [Ar]3d9

23. If two atoms or ions have the same electron configuration, they are said to

be isoelectronic with each other. Most stable ions are isoelectronic with

noble gases. Which of the following ions fit this description? (there may be many)

a. Mg+ b. P3- c. Ti4+ d. Ca6- e. Al3+ (3 pts)

24. To what group do each of the following elements belong? (1 pt ea)

a. F halogens c. Xe noble gases

b. Sr alkaline earth metals d. K alkali metals
For each group, choose which atom has the larger atomic radius and briefly explain why. (2 pts ea)
25. C or Si

26. Fe or Cu

For each group, choose which atom has the higher ionization energy and briefly explain why. (2 pts ea)

27. O or Se
28. K or Ca
For each group, choose which atom is more reactive and briefly explain why.

(2 pts ea)

29. Cr or Fe
30. S or Te

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