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A student investigated the mass of dissolved solids in 5 cm³ samples of water - AQA - GCSE Chemistry Combined Science - Question 3 - 2018 - Paper 2
Question 3
A student investigated the mass of dissolved solids in 5 cm³ samples of water. Figure 3 shows the apparatus. Figure 3 Table 2 shows the student’s results. Type of... show full transcript
Worked Solution & Example Answer:A student investigated the mass of dissolved solids in 5 cm³ samples of water - AQA - GCSE Chemistry Combined Science - Question 3 - 2018 - Paper 2
Step 1
Calculate mass X in Table 2
Answer
To find mass X in the table, we can use the data given for river water:
Mass of watch glass = 9.15 g
Mass of watch glass and dissolved solids = 9.23 g
To find mass X, we calculate the mass of dissolved solids in 5 cm³ of river water:
Mass of dissolved solids = Mass of watch glass and dissolved solids - Mass of watch glass
Mass of dissolved solids = 9.23 g - 9.15 g = 0.08 g
Thus, mass X = 0.08 g.
Step 2
Give one advantage and one disadvantage of using a larger volume.
Answer
Advantage: A larger volume provides more accurate results due to better representation and reduced error margins in measurements.
Disadvantage: A larger volume may require more time and energy to heat or process the water sample.
Step 3
Describe the difference between potable water and pure water.
Answer
Potable water contains dissolved solids and impurities, such as minerals and, possibly, chlorine to ensure safety for drinking. In contrast, pure water has no dissolved solids or impurities and is considered to have a high level of purity.
Step 4
Describe how groundwater and sea water are treated to produce potable water.
Answer
Groundwater is generally filtered and may undergo sterilization to remove pathogens and impurities. Sea water, however, is treated through desalinization processes that remove salt and other minerals, making it safe to drink.
Step 5