In today’s exercise, you will separate a heterogeneous mixture of salt, sand, and chalk (calcium carbonate, CaCO3).
Salt is the only compound in this mixture that readily dissolves in water, so washing the mixture with water will remove it from the other two components.
Addition of acetic acid (vinegar) will react with the chalk to produce carbon dioxide gas (CO2) and calcium chloride (CaCl2).
CaCl2 is soluble in water and easily separated from the sand, which is then left untouched by the acid.
Explain what the effect on the percentage of each component would be if the student did not fully dry the evaporating dish after Step 7.
Effect on Salt:
Effect on Sand:
Effect on Chalk:
It would be nice to know
Step 1.
Step 2.
Step 3.
Step 4.
Step 5.
Step 6.
Step 7.
Step 8.
etc.
If the student did not fully dry the evaporating dish after Step 7, it would have an effect on the percentage of each component in the mixture.
Effect on Salt:
The salt in the mixture is the only compound that readily dissolves in water. During Step 1, when the mixture is washed with water, the salt would dissolve in the water and could be washed away. However, if the evaporating dish is not dried properly, any remaining water could still be present in the dish. As a result, when the mixture is heated in Step 6 to evaporate the water and recover the salt, the residual water might remain in the dish. This would result in a higher percentage of water in the final mixture, thus reducing the percentage of salt.
Effect on Sand:
The sand in the mixture is insoluble in both water and acetic acid. In Step 2, when the mixture is filtered, the sand will be retained on the filter paper since it does not dissolve or react. If the evaporating dish is not dried properly, any remaining water could also be left in the dish. When the mixture is heated in Step 6, the water might not completely evaporate, and some water might mix with the sand particles. This additional water content would lead to an increased percentage of water in the final mixture and decrease the percentage of sand.
Effect on Chalk:
In Step 4, when acetic acid (vinegar) is added to the mixture, it reacts with the chalk (calcium carbonate) to produce carbon dioxide gas and calcium chloride. The carbon dioxide gas is released into the atmosphere. The calcium chloride formed is soluble in water and can be separated from the sand. If the evaporating dish is not dried properly after Step 7, any remaining water could still be present. When the mixture is heated in Step 8, the residual water might not fully evaporate, and some water might remain with the calcium chloride. This would increase the percentage of water in the final mixture and decrease the percentage of chalk.