Chapter U4.15, Problem 3E

(a)

Interpretation Introduction

Interpretation:

The mass of NaCl required to make 1 L of 0.50 M solution needs to be determined.

Concept Introduction :

0.50 M solution means there is 0.50 M of solute in 1L solution.

Answer to Problem 3E

29.25 g of NaCl will be required to make 1 L of 0.50 M solution.

Explanation of Solution

Molar mass of NaCl is 55.8 g/mol.

The number of moles can be converted to mass as follows:

  $m=n\times M$

I L must contain0.50 mole NaCl= $0.50\text{ mol}\times 58.5\text{ g/mol}=29.25g$

So 29.25 g NaCl is required to make 1 L of 0.50 M solution.

(b)

Interpretation Introduction

Interpretation:

The mass of CaCl₂ required to make 1 L of 2.0 M solution needs to be determined.

Concept Introduction :

2. 0 M solution means there is 2. 0 mol of solute in 1L solution.

Answer to Problem 3E

222 g of CaCl₂will be required to make 1 L of 2M solution.

Explanation of Solution

Molecular weight of CaCl₂is 111 g/mol.

The number of moles can be converted to mass as follows:

  $m=n\times M$

1L must contain 2. 0 mole CaCl₂$=2.0\text{ mol}\times 111\text{ g/mol=222 g}$ .

So 222 g CaCl₂ is required to make 1 L of 2.0 M solution.

(c)

Interpretation Introduction

Interpretation:

The mass of NaOH required to make 1 L of 1.5 M solution needs to be determined.

Concept Introduction :

1.5 M solution means there is 1.5 mol of solute in 1L solution.

Answer to Problem 3E

60 g of NaOH will be required to make 1 L of 1.5 M solution.

Explanation of Solution

Molecular weight of NaOH _is 40 g/mol

The number of moles can be converted to mass as follows:

  $m=n\times M$

1L must contain 1.5 mole NaOH = $1.5\text{ mol}\times 40\text{ g/mol=}60g$

So, 60 g NaOH is required to make 1 L of 1.5 M solution.