======Melting vs Dissolving======


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**Alternative titles:** Phase Change vs Solution
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====Summary====                   
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====Procedure====  
  -Gather materials for melting: equal masses of ice, butter, and chocolate in separate microwave-safe cups; balance; microwave; timer; stir sticks.
  -Gather materials for dissolving: clear jar with lid, room-temperature water, colored sugar or table sugar, spoon.
  -For melting, record the initial mass of each solid and note appearance. Place all three in the microwave.
  -Heat in 20 second intervals, checking after each interval. Stir only if needed to distribute heat. Record which samples become liquid first and the total time for each.
  -Discuss using a particle model: draw closely packed particles for the solid and more spaced, mobile particles for the liquid. Emphasize that only state changes, not identity.
  -For dissolving, pour water into the jar and add a measured spoon of sugar.
  -Stir or cap and shake to mix. Observe color and clarity changes and note that the sugar does not disappear but disperses between water particles.
  -Compare the two processes in a short table or notes: melting needs heat to change state of one substance; dissolving forms a mixture of solute and solvent without changing chemical identity.



====Links==== 
Observing & Modeling Melting vs Dissolving Lab Review - RheaultScience: 
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====Variations====
  *Repeat dissolving with salt instead of sugar or with warm vs cold water to test temperature effects.
  *Time to dissolve with and without stirring to quantify the effect of agitation and surface area.




====Safety Precautions====
  *Use microwave-safe containers and heat in short intervals to prevent overheating or splattering.
  *Handle hot containers and melted liquids with oven mitts. Allow samples to cool before moving.
  *Do not overfill closed jars when shaking to avoid pressure buildup and leaks.
  *Keep food items used for demonstrations separate from classroom food and do not consume melted butter or chocolate used as lab samples.
  *Clean spills promptly to prevent slips. Wash hands after the activity.




====Questions to Consider====
  *What changes during melting at the particle level? (Particles gain energy and move farther apart, changing from an ordered solid to a mobile liquid without changing identity.)
  *What changes during dissolving at the particle level? (Solvent particles surround and separate solute particles, dispersing them throughout the liquid to form a mixture.)
  *Why is dissolving not the same as melting? (Melting is a state change of a single substance; dissolving mixes two substances to form a solution.)
  *How do stirring and temperature affect dissolving rate? (They increase collisions between solvent and solute particles, speeding dispersion.)
  *Why might ice melt more slowly than butter in the microwave? (Different intermolecular forces and specific heat capacities lead to different energy needs for phase change.)
  *If the solution looks clear, where did the solute go? (It is present as particles between water particles; it can be detected by taste or by evaporating the water to recover the solute.)