General Chemistry I – Overview

General Chemistry I introduces the fundamental principles that govern matter and its transformations. It covers atomic structure, chemical bonding, stoichiometry, thermochemistry, and states of matter. The course begins with an understanding of atoms—protons, neutrons, and electrons—and progresses to electron configurations, periodic trends, and how these influence chemical behavior. The periodic table becomes a powerful tool to predict properties such as atomic size, ionization energy, and electronegativity.

A major component of General Chemistry I is stoichiometry, which deals with quantitative relationships in chemical reactions. Students learn to balance chemical equations and calculate amounts of reactants and products using the mole concept. This includes topics like limiting reagents, percentage yield, empirical and molecular formulas, and solution concentrations. These calculations are essential for laboratory work and industrial chemistry processes.

Another key area is energy changes in chemical reactions (thermochemistry). This includes concepts such as enthalpy, exothermic and endothermic reactions, calorimetry, and Hess’s law. Additionally, students explore gases and their behavior using gas laws such as Boyle’s law, Charles’s law, and the ideal gas equation. Together, these topics build a strong foundation for understanding more advanced chemistry concepts.

100 Practice Numerical Problems with Answers

Atomic Structure & Mole Concept

1. Number of moles in 18 g of water
   Answer: 1 mol
2. Number of molecules in 1 mol of CO₂
   Answer: $6.022 \times 10^{23}$
3. Mass of 2 mol NaCl
   Answer: 117 g
4. Moles in 44 g CO₂
   Answer: 1 mol
5. Number of atoms in 2 mol He
   Answer: $1.204 \times 10^{24}$
6. Molar mass of H₂SO₄
   Answer: 98 g/mol
7. Mass of 0.5 mol O₂
   Answer: 16 g
8. Moles in 22 g N₂
   Answer: 0.786 mol
9. Molecules in 0.5 mol H₂O
   Answer: $3.011 \times 10^{23}$
10. Atoms in 1 mol CH₄
    Answer: $5 \times 6.022 \times 10^{23}$

Stoichiometry

11. Moles of O₂ needed for 1 mol CH₄ combustion
    Answer: 2 mol
12. CO₂ formed from 1 mol CH₄
    Answer: 1 mol
13. Mass of CO₂ from 1 mol C
    Answer: 44 g
14. Limiting reagent: 2 mol H₂ + 1 mol O₂
    Answer: H₂
15. Water formed from 2 mol H₂
    Answer: 2 mol
16. Mass of O₂ needed for 12 g C
    Answer: 32 g
17. Moles of NaCl from 1 mol Na
    Answer: 1 mol
18. Yield if actual = 80 g, theoretical = 100 g
    Answer: 80%
19. Empirical formula of CH₂O
    Answer: CH₂O
20. Molecular formula if molar mass = 180
    Answer: C₆H₁₂O₆

Gas Laws

21. Volume at STP of 1 mol gas
    Answer: 22.4 L
22. Pressure if volume halves (Boyle’s law)
    Answer: Doubles
23. Volume change if temperature doubles (Charles’s law)
    Answer: Doubles
24. Pressure of 1 mol gas at 22.4 L, 273 K
    Answer: 1 atm
25. Gas constant R
    Answer: 0.0821 L·atm/mol·K
26. Moles in 44.8 L gas at STP
    Answer: 2 mol
27. Volume of 2 mol gas at STP
    Answer: 44.8 L
28. Temperature if pressure doubles (constant volume)
    Answer: Doubles
29. Density of gas formula
    Answer: $PM/RT$PM/RT
30. Pressure of gas with n=1, T=300K, V=24.6L
    Answer: 1 atm

Thermochemistry

31. Heat absorbed in endothermic reaction
    Answer: Positive
32. Heat released in exothermic reaction
    Answer: Negative
33. Specific heat formula
    Answer: $q = mc\Delta T$q=mcΔT
34. Heat for 1 g water, ΔT=10°C
    Answer: 41.8 J
35. Enthalpy change unit
    Answer: kJ/mol
36. ΔH for combustion is
    Answer: Negative
37. Hess’s law application
    Answer: Add equations
38. Calorimeter measures
    Answer: Heat
39. Heat capacity unit
    Answer: J/°C
40. Energy unit SI
    Answer: Joule

Solutions & Concentration

41. Molarity =
    Answer: mol/L
42. Moles in 1 M, 1 L solution
    Answer: 1 mol
43. 0.5 M solution means
    Answer: 0.5 mol/L
44. Dilution formula
    Answer: $M_1V_1 = M_2V_2$
45. 1 L of 2 M → diluted to 2 L
    Answer: 1 M
46. Mass of NaCl in 1 L of 1 M solution
    Answer: 58.5 g
47. ppm means
    Answer: mg/L
48. Mole fraction formula
    Answer: moles/total moles
49. Solubility unit
    Answer: g/L
50. Normality =
    Answer: eq/L

Periodic Trends

51. Atomic radius increases
    Answer: Down group
52. Ionization energy increases
    Answer: Across period
53. Most electronegative element
    Answer: F
54. Metallic character increases
    Answer: Down group
55. Smallest atom
    Answer: He
56. Largest atom
    Answer: Cs
57. Electron affinity highest
    Answer: Cl
58. Shielding effect increases
    Answer: Down group
59. Valency of Group 1
    Answer: 1
60. Valency of Group 17
    Answer: 1

Chemical Bonding

61. Bond in NaCl
    Answer: Ionic
62. Bond in H₂
    Answer: Covalent
63. Shape of CH₄
    Answer: Tetrahedral
64. Bond angle in CH₄
    Answer: 109.5°
65. Hybridization in CH₄
    Answer: sp³
66. Hybridization in C₂H₂
    Answer: sp
67. Polar molecule example
    Answer: H₂O
68. Nonpolar molecule
    Answer: CO₂
69. VSEPR theory predicts
    Answer: Shape
70. Lone pair reduces angle
    Answer: Yes

States of Matter

71. Gas compressibility
    Answer: High
72. Liquid volume
    Answer: Fixed
73. Solid shape
    Answer: Fixed
74. Intermolecular forces strongest in
    Answer: Solids
75. Boiling point increases with
    Answer: IMF strength
76. Vapor pressure increases with
    Answer: Temperature
77. Ideal gas assumption
    Answer: No interactions
78. Real gas deviation at
    Answer: High pressure
79. Diffusion rate ∝
    Answer: 1/√M
80. Graham’s law
    Answer: Rate ratio = √(M₂/M₁)

Mixed Problems

81. Moles in 9 g water
    Answer: 0.5 mol
82. Volume of 0.5 mol gas at STP
    Answer: 11.2 L
83. Mass of 1 mol O₂
    Answer: 32 g
84. Atoms in 1 mol O₂
    Answer: $2 \times 6.022 \times 10^{23}$
85. Pressure at half volume
    Answer: Doubles
86. Heat if ΔT negative
    Answer: Released
87. 1 mol ideal gas at 300K volume
    Answer: 24.6 L
88. Molarity of 2 mol in 1 L
    Answer: 2 M
89. Empirical formula from 40%C, 6.7%H, 53.3%O
    Answer: CH₂O
90. Limiting reagent concept
    Answer: Smallest product
91. Mass of 2 mol CO₂
    Answer: 88 g
92. Density of gas at STP
    Answer: M/22.4
93. Bond angle NH₃
    Answer: 107°
94. Hybridization NH₃
    Answer: sp³
95. Energy released sign
    Answer: Negative
96. Volume doubles → pressure
    Answer: Halves
97. Temperature unit SI
    Answer: Kelvin
98. Moles = mass/molar mass
    Answer: Formula
99. Avogadro number
    Answer: $6.022 \times 10^{23}$
100. Gas equation
     Answer: $PV = nRT$PV=nRT