chemistry assignment 2: counting atoms and finding molar mass (slightly more complex)\ninstructions:\na)…

chemistry assignment 2: counting atoms and finding molar mass (slightly more complex)\ninstructions:\na) count the number of atoms for each element (watch for coefficients!).\nb) calculate the total molar mass for the whole formula.\n1. 2co₂ 2c + o4 =(12×2)+(4×16)=88g\n2. 4cl₂\n3. 3h₂o\n4. 2nh₃\n5. 5o₂\n6. 2cacl₂\n7. 3nacl\n8. 2ccl₄\n9. 4ch₄\n10. 3c₂h₆\n11. 2so₂\n12. 2h₂o₂\n13. 3ch₃oh\n14. 4hcl\n15. 2ch₄ + 3o₂ (optional bonus: how many atoms total?)

chemistry assignment 2: counting atoms and finding molar mass (slightly more complex)\ninstructions:\na) count the number of atoms for each element (watch for coefficients!).\nb) calculate the total molar mass for the whole formula.\n1. 2co₂ 2c + o4 =(12×2)+(4×16)=88g\n2. 4cl₂\n3. 3h₂o\n4. 2nh₃\n5. 5o₂\n6. 2cacl₂\n7. 3nacl\n8. 2ccl₄\n9. 4ch₄\n10. 3c₂h₆\n11. 2so₂\n12. 2h₂o₂\n13. 3ch₃oh\n14. 4hcl\n15. 2ch₄ + 3o₂ (optional bonus: how many atoms total?)

Answer

Explanation:

Step1: Recall atomic masses

Carbon (C): 12 g/mol, Hydrogen (H): 1 g/mol, Oxygen (O): 16 g/mol, Chlorine (Cl): 35.5 g/mol, Sodium (Na): 23 g/mol, Calcium (Ca): 40 g/mol.

Step2: Analyze 4Cl₂

a) Count atoms

There are 4 × 2 = 8 chlorine atoms.

b) Calculate molar mass

Molar mass of Cl₂ is 2×35.5 = 71 g/mol. For 4Cl₂, molar mass is 4×71 = 284 g/mol.

Step3: Analyze 3H₂O

a) Count atoms

Hydrogen: 3×2 = 6 atoms, Oxygen: 3×1 = 3 atoms.

b) Calculate molar mass

Molar mass of H₂O is (2×1)+16 = 18 g/mol. For 3H₂O, molar mass is 3×18 = 54 g/mol.

Step4: Analyze 2NH₃

a) Count atoms

Nitrogen: 2×1 = 2 atoms, Hydrogen: 2×3 = 6 atoms.

b) Calculate molar mass

Molar mass of NH₃ is 14+(3×1)=17 g/mol. For 2NH₃, molar mass is 2×17 = 34 g/mol.

Step5: Analyze 5O₂

a) Count atoms

There are 5×2 = 10 oxygen atoms.

b) Calculate molar mass

Molar mass of O₂ is 2×16 = 32 g/mol. For 5O₂, molar mass is 5×32 = 160 g/mol.

Step6: Analyze 2CaCl₂

a) Count atoms

Calcium: 2×1 = 2 atoms, Chlorine: 2×2 = 4 atoms.

b) Calculate molar mass

Molar mass of CaCl₂ is 40+(2×35.5)=111 g/mol. For 2CaCl₂, molar mass is 2×111 = 222 g/mol.

Step7: Analyze 3NaCl

a) Count atoms

Sodium: 3×1 = 3 atoms, Chlorine: 3×1 = 3 atoms.

b) Calculate molar mass

Molar mass of NaCl is 23 + 35.5=58.5 g/mol. For 3NaCl, molar mass is 3×58.5 = 175.5 g/mol.

Step8: Analyze 2CCl₄

a) Count atoms

Carbon: 2×1 = 2 atoms, Chlorine: 2×4 = 8 atoms.

b) Calculate molar mass

Molar mass of CCl₄ is 12+(4×35.5)=154 g/mol. For 2CCl₄, molar mass is 2×154 = 308 g/mol.

Step9: Analyze 4CH₄

a) Count atoms

Carbon: 4×1 = 4 atoms, Hydrogen: 4×4 = 16 atoms.

b) Calculate molar mass

Molar mass of CH₄ is 12+(4×1)=16 g/mol. For 4CH₄, molar mass is 4×16 = 64 g/mol.

Step10: Analyze 3C₂H₆

a) Count atoms

Carbon: 3×2 = 6 atoms, Hydrogen: 3×6 = 18 atoms.

b) Calculate molar mass

Molar mass of C₂H₆ is (2×12)+(6×1)=30 g/mol. For 3C₂H₆, molar mass is 3×30 = 90 g/mol.

Step11: Analyze 2SO₂

a) Count atoms

Sulfur: 2×1 = 2 atoms, Oxygen: 2×2 = 4 atoms.

b) Calculate molar mass

Molar mass of SO₂ is 32+(2×16)=64 g/mol. For 2SO₂, molar mass is 2×64 = 128 g/mol.

Step12: Analyze 2H₂O₂

a) Count atoms

Hydrogen: 2×2 = 4 atoms, Oxygen: 2×2 = 4 atoms.

b) Calculate molar mass

Molar mass of H₂O₂ is (2×1)+(2×16)=34 g/mol. For 2H₂O₂, molar mass is 2×34 = 68 g/mol.

Step13: Analyze 3CH₃OH

a) Count atoms

Carbon: 3×1 = 3 atoms, Hydrogen: 3×4 = 12 atoms, Oxygen: 3×1 = 3 atoms.

b) Calculate molar mass

Molar mass of CH₃OH is 12+(4×1)+16 = 32 g/mol. For 3CH₃OH, molar mass is 3×32 = 96 g/mol.

Step14: Analyze 4HCl

a) Count atoms

Hydrogen: 4×1 = 4 atoms, Chlorine: 4×1 = 4 atoms.

b) Calculate molar mass

Molar mass of HCl is 1+35.5 = 36.5 g/mol. For 4HCl, molar mass is 4×36.5 = 146 g/mol.

Step15: Analyze 2CH₄ + 3O₂

a) Count atoms

Carbon: 2×1 = 2 atoms, Hydrogen: 2×4 = 8 atoms, Oxygen: 3×2 = 6 atoms. Total atoms = 2 + 8+6 = 16 atoms.

b) Calculate molar mass

Molar mass of 2CH₄ is 2×(12+(4×1)) = 32 g/mol, molar mass of 3O₂ is 3×(2×16)=96 g/mol. Total molar mass = 32 + 96=128 g/mol.

Answer:

  1. 4Cl₂: a) 8 Cl atoms, b) 284 g/mol
  2. 3H₂O: a) 6 H, 3 O atoms, b) 54 g/mol
  3. 2NH₃: a) 2 N, 6 H atoms, b) 34 g/mol
  4. 5O₂: a) 10 O atoms, b) 160 g/mol
  5. 2CaCl₂: a) 2 Ca, 4 Cl atoms, b) 222 g/mol
  6. 3NaCl: a) 3 Na, 3 Cl atoms, b) 175.5 g/mol
  7. 2CCl₄: a) 2 C, 8 Cl atoms, b) 308 g/mol
  8. 4CH₄: a) 4 C, 16 H atoms, b) 64 g/mol
  9. 3C₂H₆: a) 6 C, 18 H atoms, b) 90 g/mol
  10. 2SO₂: a) 2 S, 4 O atoms, b) 128 g/mol
  11. 2H₂O₂: a) 4 H, 4 O atoms, b) 68 g/mol
  12. 3CH₃OH: a) 3 C, 12 H, 3 O atoms, b) 96 g/mol
  13. 4HCl: a) 4 H, 4 Cl atoms, b) 146 g/mol
  14. 2CH₄ + 3O₂: a) 16 total atoms, b) 128 g/mol