Define a standard solution. (i) How would you prepare 500 cm³ of 0.2 mol/dm³ sodium carbonate solution from solid sodium carbonate? (ii) How would you dilute 500 cm³ of 0.2 mol/dm³ sodium carbonate so

Convert volume to $\text{dm}^3$:

Use the formula $\text{Moles} = \text{Concentration} \times \text{Volume}$:

Use the formula $\text{Mass} = \text{Moles} \times \text{Molar mass}$:

The mass of sodium carbonate needed is $\boxed{\text{10.6 g}}$.

1. (a) (iii)

Given:
$M_1 = 0.2 \text{ moldm}^{-3}$
$V_1 = 500 \text{ cm}^3$
$M_2 = 0.04 \text{ moldm}^{-3}$

The volume of water needed is $\boxed{\text{2000 cm}^3}$.

1. (b) (i) The titration involves $\text{NaCl}$ and $\text{AgNO}_3$, which forms $\text{AgCl}$ precipitate. This is a precipitation titration.
The suitable indicator is Potassium chromate ($\text{K}_2\text{CrO}_4$).

1. (b) (ii)

The mole ratio of $\text{NaCl}$ to $\text{AgNO}_3$ is 1:1.

Convert volume to $\text{dm}^3$:

From the 1:1 mole ratio:

Convert volume to $\text{dm}^3$:

The molarity of the sodium chloride solution is $\boxed{\text{0.08 moldm}^{-3}}$.

1. (c)

1. (d) (i) Lattice energy is the energy change that occurs when one mole of an ionic compound is formed from its gaseous ions under standard conditions. It represents the strength of the electrostatic forces between ions in a crystal lattice.