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UMUC CHEM 121 CHEM/121 CHEM121 FINAL EXAM SOLUTIONS

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Multiple Choice

1. Which of the following is NOT paired correctly? 

a) Germanium /metalloid
b) Aluminum chloride/compound
c) salty water/homogenous mixture
d) Bromine dissolved in alcohol/heterogenous mixture

2. Will a precipitate form when aqueous solutions of NaCl2 and AgNO3 are mixed? If a precipitate does form, identify the precipitate by circling the correct chemical equation in net ionic equation form.

a) NaNO3 precipitates according to Na1+(aq) + NO3-(aq) —> NaNO3(s) 
b) Na3N2 precipitates according to 3 Na2+(aq) + 2NO3-(aq) —> Ca3N2(s) + 3 O2(g) 
c) AgCl precipitates according to AgNO3(aq) + Cl-(aq) —> AgCl (s) + NO3-(aq) 
d) AgCl precipitates according to Ag+(aq) + Cl-(aq) —> AgCl (s) 
e) No precipitate forms. 

3. A graduated cylinder is filled to the 12.0 mL line with water. A solid with a mass of 14.52 g is placed in the graduated cylinder and is completely immersed in the water. If the density of the solid is 11.2 g/mL what will be the new volume reading on the graduated cylinder? 

a) 1.29 mL
b) 10.71mL
c) 13.29 g/mL
d) 14.52 mL

4. Which one of the following compounds is NOT a salt (ionic solid)? 

a) LiI
b) Al(ClO4)3
c) CNBr
d) Fe(ClO3)3
e) HBr

 

 

 

 

 

5. Which of the following does NOT have the same number of grams of carbon as 45 g of methane, CH4? 

a) 2.8 moles of CO2
b) 39.4 g C2H4
c) 1.2 x 1024 molecule CH4
d) 1.69 x 1024 atoms of graphite, C(s) 
e) 1.40 mole H2C2O4

6. The GENERAL trend as one moves from left to right across a row of the periodic table is that: 

a) atomic radii of elements decrease and first ionization energy of elements also decreases. 
b) atomic radii of elements increase and electronegativity increases. 
c) first ionization energy of elements increase and electronegativity increases. 
d) electronegativity decreases and atomic radii of elements decrease. 

7. Which of the following elements has the greatest electronegativity? 

a) oxygen
b) nitrogen
c) hydrogen
d) carbon

8. What is the energy in kJ of 1 mol of  photons with a wavelength of blue light, l = 440 nm? (h = 6.6 x 10-34 J-s, c = 3.0 x 108 m/s) 

a) 4.5 x 10-19 kJ
b) 4.5 x 10-16 kJ
c) 19.6 kJ
d) 271 kJ

9. Which is an INCORRECT size relationship between two species (“<” means “is smaller than”): 

a) Mg < Na
b) Li+ < Li
c) Mg2+ < N3-
d) Cl- < Cl

mL

10. Suppose you have a very tiny hole in your car tire, but don’t have the money to fix it. But you do have a choice of what kind of gas to fill the tire with. Which of the following choices would keep the tire inflated for the longest time? 

a) He
b) Ne
c) Ar
d) Kr
e) Xe

11. The kinetic theory of gases does NOT include: 

a) The gas particles are very small and very far apart compared to their own sizes. 
b) The gas particles repel each other. 
c) The gas particles move randomly with a distribution of speeds. 
d) The gas particles collide with one another. 
e) The collisions between gas particles are elastic (no change in kinetic energy). 

 

12. Which of the following statements is NOT true? 

a) If a gas is heated from 50°C to 100°C at constant pressure, the volume will double. 
b) If the volume of a gas is doubled at constant temperature, the pressure will be cut in half. 
c) If two containers of the same volume contain gases at the same pressure and temperature, the number of moles of gas in the containers are the same, regardless of the types of gases (as long as they behave ideally). 
d) An ideal gas has zero volume at a temperature of absolute zero. 
e) Real gases attract one another at some distances. 

13. Real gases behave most ideally at: 

a) low temperature and high pressure. 
b) low temperature and low pressure. 
c) high temperature and high pressure. 
d) high temperature and low pressure.

 

 

14. If the heat absorbed, from a 59.00 g sample, is 4814.4J and the temperature changed 85.0°C, what is the sample’s specific heat?  What was the sample? See Table

15. A white solid dissolves in water to form a solution that does not conduct electricity. What type of bonding is most likely present in the solid?  

 16. Most of the acidic substances are

17. pH scale ranges between

18. Reaction of acids and metals results in evolution of

19. The atomic number gives the numebr of

20. Which of the following statements explains why elements of the alkali metal family are highly reactive?

A. Alkali metals are easily ionized.

B. Alkali metals are negatively charged. 

C. Alkali metals have an odd number of protons. 

D. Alkali metals have an odd number of electrons.

 

 

 

21.  Bismuth-210 decays directly to polonium-210.  Which of the following must be emitted during this radioactive decay?

A. alpha particle 

B. beta particle

C. neutron

D. proton

 

22. How many grams of KCl are dissolved in 2.00 L of a 0.200 M solution of KCl?

A. 0.400 g

B. 14.9 g 

C. 29.8 g

D. 400 g

 

23. Which of the following statements describes the role of a buffer?

A. It increases the rate of a reaction. 

B. It keeps the pH of a solution within a small range.

C. It changes the oxidation states of elements in a compound. 

D. It shifts the reaction equilibrium to favor more product formation.

 

24. Antifreeze is mixed with water in a car’s radiator to help keep the solution from freezing. The graph below shows how the freezing point of a solution of antifreeze and water changes based on the percent of antifreeze in the solution. Based on the graph,

 

25. Which of the following diagrams represents a single displacement (replacement) reaction?

 

26. The equation below shows a reaction at equilibrium.

 

27. Which of the following lists three states of water in order of increasing entropy?

 

Short Answer Questions

 

1. Radium-223 is part of a radioactive decay series that gives off alpha, beta, and gamma radiation.

a. Identify the charges on alpha radiation, beta radiation, and gamma radiation.

2. What factors would cause liquid molecules  to overcome intermolecular attractive forces and become gas molecules?

 

3.  A student determines that a sample of an unidentified compound contains 0.8 mol sulfur and 2.4 mol oxygen. The student concludes that the chemical formula for the unidentified compound is S 0.8 O 2.4. The  teacher explains that this chemical formula is not possible.

 

4. Sulfur dioxide (SO2) emissions from smokestacks are reduced by a “scrubbing” mechanism in which SO2 gas reacts with crushed limestone (CaCO3) to produce a removable solid waste. The equation for the balanced reaction and the molar masses of the reactants are shown below. CaCO3(s) +SO2(g) → CaSO3(s) +  CO2(g)

 5. Glucose (C6H12O6) is formed in plants by the process of photosynthesis. The net equation for photosynthesis is shown below.

6. Explain in detail a practical application of one concept presented in the course. ( write a meaningful short assay answer).

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