Answer to Question #173065 in Chemistry for Jeremy

Question

Lesson 12. Questions 1 to 5—convert the following number of moles to number of particles:

1. 2.0 moles of CaCl₂
2. 1.5 moles of copper(II) ions
3. 0.01 moles of H₂O
4. 5.0 moles of gold atoms
5. 0.0025 moles of HCl
6. What is the mass of 1 mole of Mg atoms?
7. What is the molar mass of aluminum?
8. What is the mass of 1 mole of oxygen atoms?
9. What is the mass of 1 mole of oxygen molecules, O₂?
10. Calculate the molar mass of NaOH.
11. What is the mass of 1.0 mole of CaCl₂?
12. Calculate the molar mass of Cu(NO₃)₂.
13. Calculate the molar mass of Al₂(SO₄)₃.

Answer 1

Solution:

One mole of any substance contains 6.022×10²³ particles.

Hence,

(1) 2.0 moles of CaCl₂:

Number of CaCl₂ molecules = (2.0 mol) × (6.022×10²³ molecules / 1 mol) = 1.20×10²⁴ CaCl₂ molecules

Number of CaCl₂ molecules = 1.20×10²⁴ molecules

(2) 1.5 moles of copper(II) ions:

Number of copper(II) ions = (1.5 mol) × (6.022×10²³ ions / 1 mol) = 9.03×10²³ Cu²⁺ ions

Number of copper(II) ions = 9.03×10²³ ions

(3) 0.01 moles of H₂O:

Number of H₂O molecules = (0.01 mol) × (6.022×10²³ molecules / 1 mol) = 6.02×10²¹ H₂O molecules

Number of H₂O molecules = 6.02×10²¹ molecules

(4) 5.0 moles of gold atoms:

Number of gold atoms = (5.0 mol) × (6.022×10²³ atoms / 1 mol) = 3.01×10²⁴ Au atoms

Number of gold atoms = 3.01×10²⁴ atoms

(5) 0.0025 moles of HCl:

Number of HCl molecules = (0.0025 mol) × (6.022×10²³ molecules / 1 mol) = 1.506×10²¹ HCl molecules

Number of HCl molecules = 1.51×10²¹ molecules

(6) What is the mass of 1 mole of Mg atoms?

One mole of magnesium (Mg) atoms has a mass of 24.31 g.

(7) What is the molar mass of aluminum?

The molar mass of aluminum (Al) is 26.982 g/mol.

(8) What is the mass of 1 mole of oxygen atoms?

One mole of oxygen (O) atoms has a mass of 16 g.

(9) What is the mass of 1 mole of oxygen molecules, O₂?

One mole of oxygen molecules (O₂) has a mass of 32 g.

(10) Calculate the molar mass of NaOH.

M(Na) = 22.989 g/mol

M(O) = 15.999 g/mol

M(H) =1.0079 g/mol

So, its molar mass is 22.989 + 15.999 + 1.0079 = 39.996 g/mol

M(NaOH) = 39.996 g/mol

(11) What is the mass of 1.0 mole of CaCl₂?

The molar mass of CaCl₂ is 110.98 g/mol.

So, 1.0 mole of CaCl₂ has a mass of 110.98 g.

(12) Calculate the molar mass of Cu(NO₃)₂.

M(Cu) = 63.546 g/mol

M(N) = 14.0067 g/mol

M(O) = 15.999 g/mol

So, its molar mass is 63.546 + 2×14.0067 + 6×15.999 = 187.5534 g/mol = 187.55 g/mol

M(Cu(NO₃)₂) = 187.55 g/mol

(13) Calculate the molar mass of Al₂(SO₄)₃.

M(Al) = 26.98154 g/mol

M(S) = 32.065 g/mol

M(O) = 15.999 g/mol

So, its molar mass is 2×26.98154 + 3×32.065 + 12×15.999 = 342.146 g/mol = 342.15 g/mol

M(Al₂(SO₄)₃) = 342.15 g/mol