Heating and Cooling Curves Flashcards
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Questions and Answers

How many sections are there on a heating/cooling curve?

5

What are the two types of sections on a heating/cooling curve?

Diagonal and plateau

On a diagonal section of a heating curve, what change does the energy that is added create?

It increases the temperature

On a diagonal section of a cooling curve, what change does the energy that is released create?

<p>It decreases the temperature</p> Signup and view all the answers

On a plateau section of a heating curve, what change does the energy added create?

<p>Phase change (change of state)</p> Signup and view all the answers

On a plateau section of a cooling curve, what change does the energy released create?

<p>Phase change (change of state)</p> Signup and view all the answers

What phase change occurs on the first plateau of a heating curve?

<p>Melting</p> Signup and view all the answers

What phase change occurs on the first plateau of a cooling curve?

<p>Freezing</p> Signup and view all the answers

What phase change occurs on the second plateau of a heating curve?

<p>Boiling (Vaporization, Evaporation)</p> Signup and view all the answers

What phase change occurs on the second plateau of a cooling curve?

<p>Condensation</p> Signup and view all the answers

Does the temperature ever increase during a phase change? Why?

<p>False</p> Signup and view all the answers

What is the name of the first plateau?

<p>Heat of fusion</p> Signup and view all the answers

What is the name of the second plateau?

<p>Heat of vaporization</p> Signup and view all the answers

What phase change can occur on a heating curve during the heat of fusion?

<p>Melting</p> Signup and view all the answers

What phase change can occur on a cooling curve during the heat of fusion?

<p>Freezing</p> Signup and view all the answers

What phase change can occur on a heating curve during the heat of vaporization?

<p>Boiling (Vaporization, Evaporation)</p> Signup and view all the answers

What phase change can occur on a cooling curve during the heat of vaporization?

<p>Condensation</p> Signup and view all the answers

Are both plateaus on a heating/cooling curve the same length? If not, how do they differ?

<p>False</p> Signup and view all the answers

What accounts for the difference in lengths of the heat of fusion versus the heat of vaporization?

<p>For heat of fusion, you only have to be able to melt the substance enough to allow the molecules to slide past each other. However, on heat of vaporization you have to be able to separate the molecules completely.</p> Signup and view all the answers

What is the boiling point of water?

<p>100 C</p> Signup and view all the answers

What is the freezing point of water?

<p>0 C</p> Signup and view all the answers

What is the melting point of ice?

<p>0 C</p> Signup and view all the answers

What is the condensation point of water?

<p>100 C</p> Signup and view all the answers

As you move up the heating curve, is energy added or released?

<p>Added</p> Signup and view all the answers

As you move up the heating curve, is it endothermic or exothermic?

<p>False</p> Signup and view all the answers

As you move down the cooling curve, is energy added or released?

<p>Released</p> Signup and view all the answers

As you move down the cooling curve, is it endothermic or exothermic?

<p>False</p> Signup and view all the answers

Is melting endothermic or exothermic?

<p>False</p> Signup and view all the answers

Is freezing endothermic or exothermic?

<p>False</p> Signup and view all the answers

Is boiling endothermic or exothermic?

<p>False</p> Signup and view all the answers

Is condensation endothermic or exothermic?

<p>False</p> Signup and view all the answers

True or False: On any heating curve, energy is added and therefore it is always endothermic.

<p>True</p> Signup and view all the answers

True or False: On any cooling curve, energy is released and therefore it is always exothermic.

<p>True</p> Signup and view all the answers

True or False: A cooling curve is the reverse of a heating curve - the only difference is the sign assigned to the calculated value.

<p>True</p> Signup and view all the answers

What formula do you use to calculate the energy change on the diagonal sections of a heating/cooling curve?

<p>q = mc delta T</p> Signup and view all the answers

What formula do you use to calculate the energy change on the first plateau of a heating/cooling curve?

<p>qf = mHf</p> Signup and view all the answers

Study Notes

Heating and Cooling Curves Overview

  • Heating/cooling curves consist of 5 sections: two diagonal sections and two plateau sections.
  • Two main types of segments: diagonal (temperature changes) and plateau (phase changes).

Diagonal Sections

  • On a diagonal section of a heating curve, added energy increases temperature.
  • On a diagonal section of a cooling curve, released energy decreases temperature.

Plateau Sections

  • On a plateau section of a heating curve, added energy results in a phase change.
  • On a plateau section of a cooling curve, released energy also results in a phase change.

Phase Changes

  • The first plateau of a heating curve corresponds to melting.
  • The first plateau of a cooling curve corresponds to freezing.
  • The second plateau of a heating curve corresponds to boiling (vaporization).
  • The second plateau of a cooling curve corresponds to condensation.

Energy and Phase Changes

  • During a phase change, temperature does not increase because energy is utilized to facilitate the phase change.
  • The first plateau is referred to as heat of fusion; the second plateau is known as heat of vaporization.

Energy Change Calculations

  • For diagonal sections, the formula is q = mc delta T (where q is heat added, m is mass, c is specific heat, and delta T is the temperature change).
  • For the first plateau (melting/freezing), use qf = mHf (where Hf is heat of fusion).
  • For the second plateau (boiling/condensation), use qv = mHv (where Hv is heat of vaporization).

Temperature Points

  • The boiling point of water is 100°C.
  • The freezing point of water is 0°C.
  • The melting point of ice is 0°C.
  • The condensation point of water is 100°C.

Thermodynamic Principles

  • As you move up the heating curve, energy is added (endothermic).
  • As you move down the cooling curve, energy is released (exothermic).
  • Melting and boiling are endothermic processes, while freezing and condensation are exothermic processes.

General Understanding

  • Heating curves are always endothermic due to the addition of energy.
  • Cooling curves are always exothermic due to energy being released.
  • A cooling curve is essentially the reverse of a heating curve, differing primarily in the sign of calculated values.

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Description

This quiz focuses on key concepts related to heating and cooling curves, including the different sections and the energy changes that occur during these processes. Test your understanding of the diagonal and plateau sections, as well as the effects of energy addition on temperature. Perfect for chemistry students studying phase changes.

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