Describe a method to determine the mass of dissolved solids ina 100 cm 3 sample of river water.

Sure, here is a step-by-step method to determine the mass of dissolved solids in a 100 cm3 sample of river water:

1. Collection of Sample: Collect a 100 cm3 sample of river water. Make sure to collect the sample in a clean and sterilized container to avoid any contamination.

2. Filtration: Filter the collected sample through a pre-weighed filter paper. This will separate the suspended solids from the dissolved solids.

3. Evaporation: Transfer the filtrate (the liquid that has passed through the filter) to a pre-weighed evaporating dish.

4. Drying: Place the evaporating dish on a hot plate or in an oven and allow the water to evaporate completely. This should leave behind the dissolved solids.

5. Cooling and Weighing: After evaporation, cool the dish in a desiccator to avoid absorption of moisture from the air. Once the dish is cool, weigh it using an analytical balance.

6. Calculation: Subtract the initial weight of the evaporating dish from the final weight. The difference will give you the mass of the dissolved solids in the 100 cm3 sample of river water.

Remember to perform this experiment under the guidance of a trained professional or a teacher if you are doing it for the first time.