Alright Janet — let's do this. 5. Mwang[i] set up an apparatus for finding the percentage of humus contents in a soil by ignition. b) Outline the steps followed in carrying out the illustrated experiment. Step 1: Outline the experimental procedure. • Weigh a clean, dry crucible ($M_1$). • Add a known mass of oven-dried soil sample to the crucible. Weigh the crucible with the soil ($M_2$). • Place the crucible with the soil on a tripod stand with a gauze mat and heat it strongly using a Bunsen burner for a prolonged period, stirring occasionally. • Allow the crucible and the remaining soil (ash) to cool completely in a desiccator. • Weigh the crucible with the ash ($M_3$). • Repeat the heating, cooling, and weighing steps until a constant mass is obtained. c) Explain what happens after heating the soil and its contents. Step 2: Explain the changes during heating. • Upon strong heating, the organic matter (humus) present in the soil undergoes combustion. • This process converts the solid organic compounds into gaseous products such as carbon dioxide ($\text{CO}_2$) and water vapor ($\text{H}_2\text{O}$), which escape into the atmosphere. • The remaining material in the crucible is primarily the inorganic mineral components of the soil, often appearing as a greyish-white ash. d) Compare the mass after and before heating. Step 3: Compare the masses. • The mass of the soil after heating will be less than its mass before heating. • This reduction in mass is attributed to the loss of organic matter that was burnt off and released as gases during the ignition process. • The difference in mass ($M_2 - M_3$) represents the mass of the organic matter (humus) originally present in the soil sample. What's next? Send 'em!