Ice Cream Lab Pictures and Notes

What happened Adding the sugar, milk and vanilla together created a physical mixture Ice Cream was made because enough energy was taken out of the milk (exothermic change) to require a change in the state of matter of the mixture The energy lost by the mixture was used to increase the temperature of the ice, causing it to melt (endothermic)

Sum up The salt dissolved in to the water and lowers the melting point of the ice. This allows the water to remain a liquid well below 32 degrees. This allows the liquid mixture to change into a solid at a temp below 32 degrees The temperature of the water will not increase until all of the ice changes into liquid (EITHER the state of matter OR temperature changes, not both) until it reached a much lower than normal temperature.

How does ice lower the freezing point? Salt takes energy from the surrounding environment to break the attachments holding water molecules together and the split up the salt molecules The salt molecules then keep the water molecules from reconnecting with each other More energy must be taken out (exothermic change) to overcome the barriers in order to actually reform the ice

How Ice Cream was made I.You add energy to the salt and water mixture, which causes the ice to melt and salt to dissolve. II.The dissolved salt lowers the freezing point of water making the mixture much colder than 32 degrees III.The cold salt-water mixture pulls energy out of the milk mixture atoms IV.When enough energy is withdrawn, the mix mixture changes phase.

What you did You also added energy into the system by shaking and rubbing the zip bags, this went into melting the ice (endothermic) You hands get cold because they are transferring energy into the bag of ice (exothermic)

Was energy conserved? If the system was composed of the ingredients, salt, ice and the bags, then the answer is… no, because your hands added energy If the system includes you, then the answer is… still no, because what gives you energy and are you accounting for all the energy transfers that take place in your life during the lab?