Question

activity a: phase changes
get the gizmo ready:

• click reset. check that macro view is selected.
• set the water temperature to 20 °c.
• set the ice volume to 0 cm³.

question: how is temperature related to phase - changes?

1. predict: based on your prior knowledge, predict the following:

a. at what temperature will water change from a liquid to a solid (freeze)?
b. at what temperature will water change from a solid to a liquid (melt)?
c. at what temperature will water change from a liquid to a gas (boil)?

1. investigate: use the gizmo to explore phase changes. use the add/remove heat energy slider to control the water temperature. record your observations in your notes, then answer the questions below.

a. at what temperature does water freeze? this is the freezing point.
b. at what temperature does ice melt? this is the melting point.
c. at what temperature does water boil? this is the boiling point.

1. observe: set up the gizmo to observe freezing. what do you notice about the temperature while the water is in the process of freezing?
2. explore: use the gizmo to investigate melting and boiling. does the temperature change while either of these phase changes is occurring?
3. interpret: select the graph tab to see a graph of temperature vs. time. click the \- -\ button until the whole graph is visible. what does the graph look like during a phase change?
4. extend your thinking: why do you think the temperature does not change much during a phase change? if possible, discuss your answer with your classmates and teacher.

Explanation:

Answer:

(1A) \(0^{\circ}C\)
(1B) \(0^{\circ}C\)
(1C) \(100^{\circ}C\)
(2A) \(0^{\circ}C\)
(2B) \(0^{\circ}C\)
(2C) \(100^{\circ}C\)
(3) The temperature remains constant at \(0^{\circ}C\)
(4) No
(5) A horizontal - line segment during the phase - change
(6) Heat energy is used to break or form intermolecular forces instead of increasing the kinetic energy of the molecules, so the temperature remains constant during a phase change.