Weight of a soil sample with can is 210 g and dry weight with can is 180 g. Weight of empty moisture can is 40 g. Calculate moisture content of soil sample.
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Always ensure you subtract the tare weight of the empty container from the dry weight before dividing.
Dividing by wet soil weight is a common mistake that yields the incorrect wet-basis moisture content.
Step 1: Understanding the Concept:
Gravimetric soil moisture content is calculated as the ratio of the mass of water evaporated from the sample to the mass of the dry soil particles, expressed as a percentage. Step 2: Key Formula or Approach:
\[ \text{Moisture Content } (\%) = \frac{\text{Weight of Water } (W_w)}{\text{Weight of Dry Soil } (W_d)} \times 100 \]
Step 3: Detailed Explanation:
Given values from the measurements:
- Weight of wet soil + can = \(210\text{ g}\)
- Weight of oven-dry soil + can = \(180\text{ g}\)
- Weight of empty moisture can = \(40\text{ g}\)
1. Calculate the weight of water lost during drying (\(W_w\)):
\[ W_w = (\text{Wet soil} + \text{can}) - (\text{Dry soil} + \text{can}) \]
\[ W_w = 210\text{ g} - 180\text{ g} = 30\text{ g} \]
2. Calculate the weight of the dry soil alone (\(W_d\)):
\[ W_d = (\text{Dry soil} + \text{can}) - \text{Empty can} \]
\[ W_d = 180\text{ g} - 40\text{ g} = 140\text{ g} \]
3. Calculate the gravimetric moisture percentage:
\[ \text{Moisture Content } (\%) = \frac{30\text{ g}}{140\text{ g}} \times 100 \]
\[ \text{Moisture Content } (\%) = \frac{300}{14} \approx 21.428 \% \approx 21.4 \% \]
Step 4: Final Answer:
The correct option is 2, which corresponds to 21.4 %.
