Observations from Four Experiments that Involve MixturesExperimentProcedureObservationIWhite powder is added to water.Gas is given off.IIA solution is heated until it boils.Vapour rises, and solute is left in the beaker.IIIYellow powder is added to water.Yellow powder is added to water.IVA pure solution is added to another pure solution.A powder appears at the bottom of the beaker.In which two of the experiments did a physical change occur?
Question
Observations from Four Experiments that Involve MixturesExperimentProcedureObservationIWhite powder is added to water.Gas is given off.IIA solution is heated until it boils.Vapour rises, and solute is left in the beaker.IIIYellow powder is added to water.Yellow powder is added to water.IVA pure solution is added to another pure solution.A powder appears at the bottom of the beaker.In which two of the experiments did a physical change occur?
Solution
Para determinar en cuáles de los experimentos ocurrió un cambio físico, debemos analizar las observaciones y distinguir entre cambios físicos y químicos.
Experimento I:
- Procedimiento: Se añade un polvo blanco al agua.
- Observación: Se desprende gas.
- Análisis: La formación de gas indica una reacción química.
Experimento II:
- Procedimiento: Se calienta una solución hasta que hierve.
- Observación: El vapor se eleva y el soluto queda en el vaso.
- Análisis: La ebullición y la separación del soluto son cambios físicos.
Experimento III:
- Procedimiento: Se añade un polvo amarillo al agua.
- Observación: El polvo amarillo se añade al agua.
- Análisis: No se menciona ningún cambio, pero si el polvo simplemente se dispersa en el agua sin reaccionar, es un cambio físico.
Experimento IV:
- Procedimiento: Se añade una solución pura a otra solución pura.
- Observación: Aparece un polvo en el fondo del vaso.
- Análisis: La formación de un sólido (precipitado) indica una reacción química.
Por lo tanto, los dos experimentos en los que ocurrió un cambio físico son el Experimento II y el Experimento III.
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