Based on the observations from the heating process, we can analyze the properties of the unknown substance:
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When the temperature reaches 100 °C, the water boils and you are left with a white crystalline substance. This suggests that the unknown solid substance is soluble in water and has a higher boiling point than water, allowing it to remain solid after the water has evaporated.
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When the temperature reaches 200 °C, everything in the container becomes a liquid. This indicates that the solid substance melts at this temperature.
Now, let's analyze the options:
A. Lead: Lead has a melting point of about 327.5 °C and would not dissolve in water, so it cannot be the unknown substance.
B. Aluminum: Aluminum has a melting point of about 660 °C and also does not dissolve in water, so it is not the unknown substance.
C. Table Salt (Sodium Chloride): Table salt has a melting point of about 801 °C and can dissolve in water, but it does not melt at the temperature you specified (200 °C).
D. Table Sugar (Sucrose): Table sugar has a melting point of about 186 °C and dissolves in water. After the water evaporates, the sugar will remain as a solid until it reaches its melting point and becomes liquid.
Based on the facts laid out, the unknown substance is most likely D. table sugar.
2 answers