Docsity
Docsity

Prepare for your exams
Prepare for your exams

Study with the several resources on Docsity


Earn points to download
Earn points to download

Earn points by helping other students or get them with a premium plan


Guidelines and tips
Guidelines and tips

Chemistry Exam Problems and Solutions, Summaries of Chemistry

A set of chemistry exam problems along with their solutions. The problems cover various topics in chemistry including molecular mass calculations, moles and mass percent, empirical and molecular formulas, balancing chemical equations, stoichiometry, and thermodynamics. The solutions demonstrate how to apply chemical concepts and equations to solve the problems.

What you will learn

  • How many oxygen atoms are in 34.5 g of NaNO3?
  • Under which conditions would ammonia (NH3) behave more like an ideal gas?
  • What is the molecular mass of table sugar sucrose (C12H22O11)?
  • What is the mass percent of oxygen in the amino acid, serine, which has the molecular formula C3H7NO3?
  • How many moles of NaBr are needed to react with 0.75 moles of Fe according to the given reaction?
  • What is the volume occupied by 20.0 g of argon gas at a pressure of 1.05 atm and a temperature of 25.0 ºC?

Typology: Summaries

2021/2022

Uploaded on 09/12/2022

sheela_98
sheela_98 🇺🇸

4.2

(12)

234 documents

1 / 8

Toggle sidebar

This page cannot be seen from the preview

Don't miss anything!

bg1
1.
Calculate the molecular mass of table sugar sucrose (C12H22O11).
A.
342.30 amu
C.
320.05 amu
B.
160.03 amu
D.
171.15 amu
2.
How many oxygen atoms are in 34.5 g of NaNO3?
A.
2.34 1023 atoms
C.
B.
5.81 1026 atoms
D.
3.
Calculate the mass percent of oxygen in the amino acid, serine, which has the molecular
formula C3H7NO3.
A.
0.46%
C.
B.
15.22%
D.
4.
Aluminum chloride is 20.2% aluminum by mass. Calculate the mass of aluminum in a
35.0 gram sample of aluminum chloride.
A.
6.49 g
C.
B.
20.4 g
D.
5.
A laboratory analysis of citric acid (compound responsible for the sour taste of lemons)
determined the following mass percent composition 37.51% carbon, 4.20% hydrogen and
58.29% oxygen. Find the empirical formula.
A.
C3H4O3
C.
B.
C6H8O7
D.
pf3
pf4
pf5
pf8

Partial preview of the text

Download Chemistry Exam Problems and Solutions and more Summaries Chemistry in PDF only on Docsity!

  1. Calculate the molecular mass of table sugar sucrose (C 12 H 22 O 11 ).

A. 342.30 amu C. 320.05 amu B. 160.03 amu D. 171.15 amu

  1. How many oxygen atoms are in 34.5 g of NaNO 3?

A. (^) 2.34  1023 atoms C. (^) 7.33  1023 atoms B. (^) 5.81  1026 atoms D. (^) 8.2 1  1022 atoms

  1. Calculate the mass percent of oxygen in the amino acid, serine, which has the molecular formula C 3 H 7 NO 3.

A. 0.46% C. 13.33%

B. 15.22% D. 45.67%

  1. Aluminum chloride is 20.2% aluminum by mass. Calculate the mass of aluminum in a 35.0 gram sample of aluminum chloride.

A. 6.49 g C. 7.07 g B. 20.4 g D. 5.24 g

  1. A laboratory analysis of citric acid (compound responsible for the sour taste of lemons) determined the following mass percent composition 37.51% carbon, 4.20% hydrogen and 58.29% oxygen. Find the empirical formula.

A. C 3 H 4 O 3 C. C 6 H 8 O 5

B. C 6 H 8 O 7 D. C 5 H 8 O 7

  1. A compound has an empirical formula of CH 2 O and the molar mass of the compound is 180g/mol. What is the molecular formula?

A. CH 12 O C. C 6 H 12 O 6

B. C 6 H 6 O D. C 12 H 24 O 12

  1. Consider the following unbalanced chemical equation. When properly balanced, what is the coefficient of HCl?

HCl( aq ) + O 2 ( g ) → H 2 O( l ) + Cl 2 ( g )

A. 1

B. 2

C. 3

D. 4

  1. How many moles of NaBr are needed to react with 0.75 moles of Fe according to the following reaction?

Fe + 3NaBr → FeBr 3 + 3Na

A. 0.75 moles C. 0.25 moles B. 1.50 moles D. 2.25 moles

  1. Urea (CH 4 N 2 O) is a common fertilizer that can be synthesized by the reaction of ammonia with carbon dioxide:

2NH 3 ( aq ) + CO 2 ( aq ) → CH 4 N 2 O( aq ) + H 2 O( l )

Starting with 50.0 g of NH 3 , how many grams of CO 2 are required for the NH 3 to be completely consumed?

A. 64.6 g C. 1.47 g B. 129 g D. 25.0 g

  1. Solutions of calcium hydroxide, Ca(OH) 2 , and sodium phosphate, Na 3 PO 4 , are mixed. Write the balanced complete ionic equation for the reaction:

___Ca(OH) 2 ( aq ) + ____Na 3 PO 4 ( aq ) →

A. Ca2+( aq ) + 2OH( aq ) + 3Na+( aq ) + PO 43 ( aq ) → 3Na+( aq ) + 2OH( aq ) + CaPO 4 ( s ) B. 3Ca2+( aq ) + 2OH( aq ) + 3Na+( aq ) + 2PO 43 ( aq ) → 3Na+( aq ) + 2OH( aq ) + Ca 3 (PO 4 ) 2 ( s ) C. 3Ca2+( aq ) + 6OH( aq ) + 6Na+( aq ) + 2PO 43 ( aq ) → 6Na+( aq ) + 6OH( aq ) + Ca 3 (PO 4 ) 2 ( s ) D. 3Ca2+( aq ) + 2PO 43 ( aq ) → Ca 3 (PO 4 ) 2 ( s )

  1. It requires 23.56 mL of 0.105 M sodium hydroxide to neutralize 15.00 mL of a sulfuric acid (H 2 SO 4 ) solution. Determine the concentration of the sulfuric acid (H 2 SO 4 ) solution.

A. 0.0825 M C. 0.169 M

B. 0.0401 M D. 0.311 M

  1. What is the oxidation number of sulfur in SO 4 2−?

A. +4 C. +

B. − 2 D. +

  1. Which of the following are redox reactions?

I. CuSO 4 + 2NaOH → Cu(OH) 2 + Na 2 SO 4 II. 2Al + 3MgSO 4 → 3Mg + Al 2 (SO 4 ) 3 III. 2(NH 4 ) 3 PO 4 + 3Ba(NO 3 ) 2 → Ba 3 (PO 4 ) 2 + 6NH 4 NO 3 IV. 2HNO 3 + 3H 3 AsO 3 → 2NO + 3H 3 AsO 4 + H 2 O

A. I and II C. All of them B. III and IV D. II and IV

  1. Convert 32 pounds per square inch (psi) into mmHg. (Note: 14.7 psi = 1 atm, 1 Pa = 1N/m2, 1 atm = 101.325 Pa, 1mmHg = 1 torr)

A. (^) 8.1  102 mmHg C. 1.7 × 103 mmHg B. (^) 1.0  105 mmHg D. 2.2 mmHg

  1. A balloon has an initial volume of 3.45 L. What will the volume be if the temperature is raised from 24°C to 32°C?

A. 3.54 L C. 3.35 L

B. 4.60 L D. 2.58 L

  1. What is the volume occupied by 20.0 g of argon gas at a pressure of 1.05 atm and a temperature of 25.0 C?

A. 39.1 L C. 466 L

B. 11.7 L D. 0.978 L

  1. Determine the density in g/L of an unknown gas given that a 14.5 gram sample contains 2.00 moles at 25oC and 745 mmHg.

A. 0.00123 g/L C. 3.49 g/L B. 49.1 g/L D. 0.291 g/L

  1. A 1.00 L mixture of helium, hydrogen, and xenon gas has a total pressure of 645 torr at 298 K. If the partial pressure of helium is 341 torr and the partial pressure of hydrogen is 112 torr, how many moles of xenon are present in the mixture?

A. (^) 0.130  10 ^2 mol C. (^) 1.13  10 ^3 mol B. (^) 1.13  10 ^1 mol D. (^) 1.03  10 ^2 mol

  1. A system absorbs 185.5 kJ of heat as it expands to do 592 J of work (by the system) on the surroundings. What is the change in internal energy of the system?

A. 184.9 kJ C. 186.6 kJ B. (^) 409.9 kJ D. 722.9 kJ

  1. In recent years, scientists have become concerned about the quantity of which one of the following gases rising in the atmosphere and trapping heat, thus causing global warming?

A. CO C. NO 2

B. CO 2 D. CF 4

  1. What are the correct coefficients to balance the following equation and what is the oxidation number for Mn on the left (reactant)?

KMnO 4 + HCl → KCl + MnCl 2 + H 2 O + Cl 2

A. (1,8,1,1,7,3) ;  7 C. (2,16,6,4,7,2) ; +

B. (2,16,2,2,8,5) ; +7 D. (4,8,1,4,10,7) ; +

CHE 105 FALL 2012 Exam 2 key

  1. A
  2. C
  3. D
  4. C
  5. B
  6. C
  7. D
  8. D
  9. A
  10. A
  11. A
  12. A
  13. D
  14. B
  15. C
  16. A
  17. C
  18. D
  19. C
  20. A
  21. B
  22. D
  23. D
  24. B
  25. D
  26. B
  27. C
  28. A
  29. B
  30. B