Record your calculations and results on the worksheet. Present your findings and explain your calculations.

Here's an explanation of the concepts and calculations from the image.

The "Worked Example 2.2" illustrates how to determine the relative mass of an unknown substance using a beam balance, comparing it to a carbon-12 sample.

Worked Example 2.2 Explanation:
The example uses an analogy with beads.

• a) A carbon-12 sample is represented by 12 beads. By definition, carbon-12 has a relative atomic mass of 12. This implies that each carbon-12 bead in this analogy has a relative mass of 1 unit.
• b) An unknown sample is represented by $x$ beads.
• c) To find the relative mass of the unknown sample, the example assumes that $x$ beads of the unknown sample have the same total mass as the 12 carbon-12 beads when balanced. Therefore, the total relative mass of the $x$ unknown beads is 12 units. The formula $A = \frac{12}{\text{Number of beads in unknown sample}} = \frac{12}{x} = y$ calculates the relative mass per bead of the unknown sample. So, $y$ represents the relative mass of one bead of the unknown substance.

Activity 2.2: Understanding relative molecular mass
Relative molecular mass ($M_r$) is the sum of the relative atomic masses ($A_r$) of all the atoms in a molecule. We will use the approximate relative atomic masses: Hydrogen ($\text{H}$) $\approx 1.0$, Carbon ($\text{C}$) $\approx 12.0$, and Oxygen ($\text{O}$) $\approx 16.0$.

1) For Water ($\text{H}_2\text{O}$):