Warmer or cooler?

Ms. Dayna MartínezSTARS-USF

Maniscalco Elementary

What’s a thermometer?

• A thermometer is an instrument that measures temperature

• Thermo – heat• Meter – measure

• The thermometer measures temperatures in Fahrenheit (F), Celsius (C) and another scale called Kelvin (K). Fahrenheit is used mostly in the United States, and most of the rest of the world uses Celsius. Kelvin is used by scientists.

How does a thermometer works?

• A thermometer has a thin red or silver line that grows longer when it is hotter and goes down in cold weather.

• This liquid is sometimes colored alcohol but can also be a metallic liquid called mercury.

• Both mercury and alcohol grow bigger when heated (volume of the liquid increases) and smaller when cooled (volume of the liquid decreases).

• Inside the glass tube of a thermometer, the liquid has no place to go but up when the temperature is hot and down when the temperature is cold.

• Numbers are placed alongside the glass tube that mark the temperature when the line is at that point.

Parts of a thermometer

Glassbulb

Tube of glass

Scale

Liquid

How to read a thermometer?

• Place the thermometer in the substance

• Wait a little for the thermometer to display the temperature

• Your eyes should be level with the top of the liquid in the tube to read it accurately

Now, you tell me!

Endothermic Reaction• Reaction that absorbs heat• Temperature decreases

+

When cream of tartar is mixed with water, temperature drops.

Substance 1 + Substance 2 + Energy New substance

Temperature

Exothermic Reaction• Reaction that releases heat• Temperature increases

All combustion reactions are exothermic.

Substance 1 + Substance 2 Energy + New substance

Temperature

Heat transfer• Heat is the transfer of thermal

energy between objects with different temperatures.

• Thermal energy travels from a warmer object to a cooler object.

When you mix hot water with cold water, the heat will transfer from the hot water to the cold water until they reach thermal equilibrium.

Ways heat can move through a system

• Conduction– The transfer of heat from one object

directly to another.

Ways heat can move through a system

• Convection– The transfer of heat through the

movement of a gas or a liquid.

Ways heat can move through a system

• Radiation– The transfer of energy by means of waves

that move through matter and space.

Insulators and conductors

• An insulator is a material that is a poor conductor of heat energy.

• A conductor is a material that allows the conduction of heat energy.

Questions?