Heat and Energy
A hot iron block is placed in a bucket of cold water. What best describes the heat transfer?
a) The energy gained by the water will equal the energy lost by the surroundings
b) The energy lost by the water and the iron block will equal the energy lost by the surroundings
c) The energy lost by the metal ball will equal the energy gained by the water
d) The energy gained by the metal ball will equal the energy gained by the water
c) The energy lost by the metal ball will equal the energy gained by the water
What is the molar mass of Al2S3?
145.06g
How do you increase the thermal energy of an object?
a) slide it across the ground
b) run an electric current through it
c) put it in the freezer
d) heat it
d) heat it
Which is an example of a decomposition reaction?
a) ZnCO3 -> ZnO + ZnCO2
b) 2H2 + O2 -> 2H2O
a) ZnCO3 -> ZnO + ZnCO2
How does energy move?
What will increase the thermal energy of a bowling ball?
a) Roll it on the floor
b) Run an electric current through it
c) Put it into the freezer
d) Heat the bowling ball
d) Heat the bowling ball
What is the percent yield if you calculate 45.3g of O2 and actually produce 41.2g of O2?
90.9% yield
Water has a specific heat of 4.18. Iron has a specific heat of .45. What does this mean about water's specific heat?
a) it requires MORE energy to increase water's temperature
b) it requires LESS energy to change water's temperature
a) it requires MORE energy to increase water's temperature
What type of reaction always produces water (H2O) and carbon dioxide (CO2)?
Combustion
Collision theory is when particles collide to make _______ occur
Chemical reactions
Label the heat diagram
a) Final energy
b) Released
c) Reactants
d) Initial Energy
e) Products
What is theoretical yield? How is it different from actual yield?
Theoretical yield is how much mass you expect to calculate. Actual yield is how much mass is produced.
What has greater potential thermal energy, a 1lb puck of iron at 40C or a 2,000 ton iceberg?
Iceberg
What type of reaction is the following chemical equation?
BaCl2 + MgSO4 -> BaSO4 + MgCl2
Double Replacement
Why do chemists use moles in chemistry calculations?
Because they are a constant value.
Is the following reaction endothermic or exothermic?
C5H12 + O2 → CO2 + H2O + 100kJ
Exothermic, heat is released
How many grams of CO2 are produced if you react 60 grams of C3H8?
C3H8 + 5O2 -> 3CO2 + 4H2O
179.4g
Which is always a REACTANT in a combustion reaction?
a) Oxygen
b) Water
c) Heat
d) Carbon dioxide
a) Oxygen
Which of these reactions is a single replacement reaction?
a) NaCl + AgNO3 -> NaNO3 + AgCl
b) 3Ca + 2AlBr3 -> 2Al + 3CaBr2
b) 3Ca + 2AlBr3 -> 2Al + 3CaBr2
Which of the following is a synthesis reaction?
a) 2K + Cl2 -> 2KCl
b) 3Be + 2GaCl3 -> 2Ga + 3BeCl2
a) 2K + Cl2 -> 2KCl
How much heat energy is released when 30g of of water is chilled from 10C to 0C? (The specific heat for water is 4.18) Is this reaction endo or exothermic?
-1254J and exothermic because heat is being released
If 60 grams of propane (C3H8) reacts with 600 grams of oxygen (O2), which is the limiting reactant and which is the excess reactant?
C3H8 + 5O2 -> 3CO2 + 4H2O
Limiting reactant - C3H8
Excess Reactant - O2
For chemical reactions to occur, reactant particles must ________ so that the kinetic energy needed to break bonds is available.
Collide
Which type of reactions are always exothermic?
a) Synthesis
b) Double Replacement
c) Combustion
d) Single Replacement
c) Combustion
Which one is NOT an exothermic reaction?
a) Burning a candle
b) Hand warmer in your pocket
c) 6CO2 + 6H2O + heat -> C6H12O6 + 6O2
d) An energy diagram where the energy of the products is LESS than the energy of the reactants.
c) 6CO2 + 6H2O + heat -> C6H12O6 + 6O2