Quiz 3 Objectives 1-10 Chemistry

• A combustion reaction is an exothermic reaction between a fuel and oxygen, often producing flames.


  True
• What products are always made in a combustion reaction?Water, H2O

  CO2
• Which compound would not combust?

  Iron (Fe)

  methane (CH4)

  acetone (C3H6O)

  salt (NaCl)

  salt (NaCl)
• Metals always produce a flame when they combust

  False
• Define and describe combustion.

  A combustion reaction is an endothermic reaction between a fuel and oxygen, often producing flames.

  CxHy (g) + O2 (g) = CO2 (g) + H2O (g)
• Combustion


  A chemical reaction in which an element or a compound reacts with oxygen and releases energy in the form of heat and light
• Typical combustion reactions occur between a hydrocarbon and oxygen
• Combustion may also occur between a sugar/alcohol and oxygen reaction and create the same products
• Combustion of metals

  Does not produce a flame and is typically known as oxidation
• Ionic salts rarely combine with oxygen in a combustion reaction
• Most ionic compounds do not combust
• Most molecular covalent compounds do combust, especially those that contain carbon and hydrogen
• Most elemental metals combust
• Water and carbon dioxide do not combust
• Define energy.


  A measure of the work involved in moving or changing something.

  Energy is a measure of how much you can make or change something
• Define exothermic reactions. 


  Heat is transferred from a system to the surroundings; heat-releasing.
• Define endothermic reactions.


  Heat transfers from the surroundings to the system; heat-absorbing.
• Distinguish between endothermic and exothermic reactions.

  An ice cube melts after being left out on the table - Endothermic

  Cooking an egg in a frying pan - Endothermic

  Burning a match - Exothermic

  The human body uses the energy provided from food digestion - Exothermic

  Morning dew forming on grass and plants - Exothermic

  Dynamite explodes in the destruction of a building - Exothermic

  Making ice cubes - Endothermic

  A puddle of water evaporates - Endothermic

  Plants making sugar through photosynthesis - Exothermic

  Nuclear fission - Exothermic

  Converting frost to water vapor - Endothermic
• Define specific heat capacity.


  The amount of heat required to raise the temperature of 1 gram of a substance by 1°C.
• Is this exothermic or endothermic?

  Exothermic

  
• Is this exothermic or endothermic?

  Endothermic

  
• Label:

  Red -

  Yellow -

  Green -

  Blue -

  Brown -

  q=mcat

  q=mHfus

  q=mcat

  q=mHvap

  q=mcat

  
• specific heat of solid water (c)=

  specific heat of liquid water (c) =

  specific heat of gaseous water (c)=

  Hfus =

  Hvap=

  0.5 cal/g(°C)

  1.00 cal/g(°C)

  0.5 cal/g(°C)

  79.9 cal/g

  539 cal/g
• The specific heat of water used in a calorimetry experiment is

  1.0 cal/g*C.
• Calorimetry is the science of measuring the amount of heat transferred in a chemical or physical change.