QUIZ ON ACIDS & BASES AT THE BEGINNING OF CLASS. TAKE A FEW MINUTES AND STUDY!! PICK UP THE TWO HANDOUTS
Heat and Energy
What is energy? The ability to do work or produce heat.
Define potential Energy Energy due to composition- BONDS- or position
Define Kinetic Energy Energy of motion
Kinetic energy is directly related to… Constant random motion of atoms or molecules.. And is proportional to …. Temperature
What 3 things does the potential energy of a substance depend upon? 1. The type of atoms in the substances 2. Numbers and type of chemical bonds 3. Particular way atoms are arranged
State the Law of Conservation of Energy Energy cannot be created or destroyed but can change from one form to another.
Describe how octane contains chemical potential energy Strength of stored energy in bonds between C-H
What symbol is used to represent heat? QQ
Define heat The transfer of energy from warmer objects to cooler.
Define calorie The heat required to raise 1 gram of pure water 1 degree celsius
What is another name for a nutritional Calorie? Kilocalorie
What is the difference between 1 nutritional Calorie and 1 calorie? 1C = 1000c C is a food calorie. Little c is defined as the heat required to raise 1 gram of pure water 1 degree celsius.
If a food has 10,000 calories, how many Calories does it contain? 10,000 cal x 1 Cal = 10Cal 1000 cal
What is the SI unit of heat and energy? Joule
One joule =.2390 calories One calorie = joules
. A fruit and oatmeal bar contains 142 nutritional Calories. Convert to calories. 142 Calories x 1000 calories = 142,000 calorie 1 Calorie
Define specific heat The amount of heat required to raise the temperature of 1 gram of a substance 1 degree celsius.
How many joules must be absorbed by each gram of water to raise the temperature of one gram of a substance one degree celsius? j/g°C
What is the specific heat of A. Water B. Ice C. Iron-.449 D. Gold-.129
What can water do because of its high specific heat? Absorb large amounts of heat and cold.
Why is it good to plant vineyards and orchards near large bodies of water? Water absorbs the temperature of the surrounding air to keep the temperature constant.
Q= M x C x ∆T Q = heat (Calorie or Joules) M = mass (grams) C = specific heat (j/g°C) ∆T = change in temperature (°C)
If the temperature of 34.4 g of ethanol increased from 25.0 C to 78.8 C, how much heat has been absorbed by the ethanol? (C= 2.44 j/g°C )
Q= x M= 34.4 C= 2.44 ∆T= (78.8 – 25.0)
Q = M x C x ∆T Q= 2.44 x 34.4 x 53.8 Q= J
A 155 g sample of an unknown substance was heated from 25.0 °C to 40.0 °C. In the process, the substance absorbed 5696 J of energy. What is the specific heat of the substance?
Q = M x C x ∆T Q = 5696 J M = 155 g C = X ∆T = (40 °C– 25°C)
Q = M x C x ∆T 5696 J = 155 g x C x 15°C C = 2.45 j/g°C
Calorimeter A device used to measure heat content.