Describe the preparation of dry carbon (IV) oxide and state Graham's law of diffusion.

Here are the answers to your questions:

8. To prepare and collect dry carbon (IV) oxide (CO$_2$), the setup typically involves:

   • A conical flask containing marble chips (calcium carbonate) and a thistle funnel through which dilute hydrochloric acid is added.
   • A delivery tube leads the produced gas from the conical flask into a wash bottle containing concentrated sulfuric acid to dry the CO$_2$.
   • Another delivery tube then carries the dry CO$_2$ into a gas jar or test tube, where it is collected by downward delivery (upward displacement of air) because CO$_2$ is denser than air.

   The reaction is:

   $$\text{CaCO}_3\text{(s)} + 2\text{HCl(aq)} \longrightarrow \text{CaCl}_2\text{(aq)} + \text{H}_2\text{O(l)} + \text{CO}_2\text{(g)}$$

9. a) Graham's law of diffusion states that the rate of diffusion of a gas is inversely proportional to the square root of its molar mass (or density), provided the temperature and pressure are constant. Mathematically, for two gases A and B:

   $$\frac{\text{Rate}_A}{\text{Rate}_B} = \sqrt{\frac{M_B}{M_A}}$$

   where $M_A$ and $M_B$ are the molar masses of gases A and B, respectively.