Read solubility curves; what speeds dissolving
Grade 10 Science Worksheet - Building Confidence
Circle the best answer, or write your answer on the line.
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Solubility in 100 g of water (rounded textbook values)
temperature (°C) KNO₃ (g) NaCl (g) NaHCO₃ (g) 0 13 36 6.9 20 32 36 9.6 40 64 36 12.7 60 110 37 16.5 80 169 38 19.7 100 246 39 23.6 Ari stirs 120 g of KNO₃ into 75 g of water at 40 °C. By the table, how many grams stay undissolved?
Bo stirs 60 g of KNO₃ into 150 g of water at 20 °C. By the table, how many grams stay undissolved?
Esme stirs 250 g of KNO₃ into 120 g of water at 60 °C. By the table, how many grams stay undissolved?
A solution holds 40 g of KNO₃ in 100 g of water at 40 °C. By the table, how would you describe it, Jun?
- Saturated: 40 g is a lot of solid for 100 g of water
- Supersaturated: 40 g is more than the 32 g that dissolves at 20 °C
- Unsaturated: it can still dissolve 24 g more at 40 °C
From 20 °C to 80 °C, which solid's solubility rises by the most grams per 100 g of water, Kira?
- KNO₃, which rises by 169 g, the value at 80 °C
- KNO₃, which rises by 137 g (32 g to 169 g)
- NaCl, since it is the most soluble of the three at 20 °C
Luz stirs 20 g of NaHCO₃ into 100 g of water at 60 °C. What happens?
- All 20 g dissolves, because the water is hot and hot water dissolves everything
- None dissolves: baking soda needs water near 100 °C before any of it dissolves
- Only about 16.5 g dissolves; the other 3.5 g stays as solid at the bottom
Solubility in 100 g or 100 mL of water (rounded textbook values and HSDB)
temperature (°C) KNO₃ (g per 100 g) CO₂ (mL per 100 mL) 0 13 171 20 32 88 60 110 36 How much less CO₂ does 100 mL of water hold at 60 °C than at 20 °C, Milo?
- 52 mL less (88 − 36)
- 36 mL less, the reading at 60 °C
- 83 mL less (171 − 88), the drop from 0 to 20 °C
A sealed soda stays fizzy. When the cap comes off, bubbles rush out. What lets the CO₂ escape, Noah?
- Opening the cap warms the soda, so CO₂ dissolves less
- The pressure above the liquid drops, so less CO₂ can stay dissolved
- Air rushing in pushes the CO₂ out of the liquid
Time for 10 g of sugar to dissolve in 100 mL of water (example data)
trial temperature (°C) stirred form time (s) A 25 no cubes 410 B 25 yes cubes 150 C 25 yes powder 25 D 60 yes powder 9 Trial A to trial B changed one thing and sped up dissolving. What was it, and why does it help, Ren?
- Crystal size: stirring broke the cubes into powder
- Stirring: it carries syrupy water away so fresh water reaches the sugar
- Temperature: warmer water holds more sugar
Trial D finished fastest. Does D show that 60 °C water holds more sugar than 25 °C water, Zee?
- Yes: 9 s is a shorter time, which means a higher limit
- No: all 10 g dissolved in both, so the table shows speed, not the limit
- Yes: hot water dissolves more of every solid