REVIEW FOR QUIZ
HEAT
• Heat is measured in ____ and is represented with
the symbol ___.
• Temperature is measured in ___.
• Mass is measured in ____.
• Specific heat is measured in ___ and is represented
with the symbol ____.
•
•
•
•
Joules, Q
Degrees Celsius
Grams
J/g°C, c
• You eat a snack that is 20 g carbs, 4 g fat and
1 g protein. Give the total calories for each
macromolecule and then give the total
calories for the snack.
•
•
•
•
20 x 4 = 80 Calories
4 x 9 = 36 Calories
1 x 4 = 4 Calories
Total = 120 Calories
1000 calories = 1 kCal = 1 Calorie
1 calorie= 4.184 Joules
Convert the following:
• 120 J = ___ calories
• 250 Calories = ____ energy calories
120 J
1 cal_ = 28.7 cal
4.184 J
250 C 1000 cal = 250,000 cal
1C
• How many joules of energy are absorbed by
250g of water if its temperature rises from
30.0°C to 95.0°C?
• Q= mcΔT
• Q = (250g)(4.184J/g°C)(65°C)
• Q= 67,990 J
• Convert this answer into nutritional calories (c)
• 67,990J 1cal
1C____ 16.25 C
4.184J
1000cal
• How many Joules of energy are released
if a block of metal that weighs 250 g
with a specific heat of 0.234 J/g°C is
cooled from 400 °C to 285°C ?
Q= mcΔT
Q = (250 J)(0.234J/g°C)(115°C)
Q = 6,727.5 J
• What is the specific heat of a 50 g piece of
metal that takes 300 J of energy to raise the
temperature by 40°C?
• Q= mcΔT
• 300 J = (50 g)(c)(40°C)
• c = 0.15 J/g°C
• You place a 450 g block of metal in a beaker until
the metal reaches a temperature of 85°C. You
place the metal in a 250 mL of water in another
beaker and measure the temperature to be
30.0°C. When the metal is placed into the water,
the final temperature of the system reaches
37.5°C. What is the specific heat of the metal?
• mcΔT = mcΔT
(450g)(c)(47.5°C) = (250g)(4.184J/g°C) (7.5°C)
• 0.42J/g°C