Chemical Reactions Flashcards
To distinguish between physical and chemical changes
Chemical Change:
Forms new substances with different properties.
Involves breaking and forming chemical bonds, altering the chemical composition.
Physical Change:
Alters the substance’s physical state or appearance.
Processes like melting, freezing, or dissolving occur without changing the chemical composition.
To define what a chemical reaction is
A chemical reaction occurs when substances transform into new ones as the bonds between atoms break and rearrange, resulting in different substances.
- To describe the word equation of reaction of metals with oxygen, acid and water
Reaction of Metals with Oxygen:
Metal + Oxygen → Metal Oxide
For example:
Iron + Oxygen → Iron Oxide
4Fe + 3O2 → 2Fe2O3 (balanced chemical equation)
Reaction of Metals with Acid:
Metal + Acid → Salt + Hydrogen gas
For example:
Zinc + Hydrochloric Acid → Zinc Chloride + Hydrogen
Zn + 2HCl → ZnCl2 + H2 (balanced chemical equation)
Reaction of Metals with Water:
Metal + Water → Metal Hydroxide + Hydrogen gas
For example:
Sodium + Water → Sodium Hydroxide + Hydrogen
2Na + 2H2O → 2NaOH + H2 (balanced chemical equation)
List the signs/indicators that a chemical reaction has taken place
- Color Change
- Evolution of Gas
- Temperature Change
- Release or Absorption of Light
- Change in Odor
- Change in Physical State
- Formation of Heat or Flames
Name the salts produced with acid and metal reactions
Hydrochloric Acid (HCl):
Metal + Hydrochloric Acid → Metal Chloride + Hydrogen gas
Example: Zinc + Hydrochloric Acid → Zinc Chloride + Hydrogen
Zn + 2HCl → ZnCl2 + H2
Sulfuric Acid (H2SO4):
Metal + Sulfuric Acid → Metal Sulfate + Hydrogen gas
Example: Magnesium + Sulfuric Acid → Magnesium Sulfate + Hydrogen
Mg + H2SO4 → MgSO4 + H2
Nitric Acid (HNO3):
Metal + Nitric Acid → Metal Nitrate + Nitrogen Dioxide gas + Water
Example: Copper + Nitric Acid → Copper Nitrate + Nitrogen Dioxide + Water
3Cu + 8HNO3 → 3Cu(NO3)2 + 2NO2 + 4H2O
Describe the reactivity series of metals
A reactivity series lists metals by their reactivity, with the most reactive at the top and least reactive at the bottom. It aids in predicting metal reactions with water, acids, and other substances.
- Describe what a displacement reaction is
In a displacement reaction, a more reactive element replaces a less reactive one in a compound, forming a new compound and releasing the displaced element.
Write single displacement reactions between metal and metal oxides
Metal + Metal Oxide:
Metal A + Metal Oxide B –> Metal B + Metal Oxide A
Examples:
Predict if the reactions occur using the reactivity series
Iron + Copper(II) Oxide:
- Iron (Fe) is less reactive than copper (Cu).
- No reaction occurs because iron cannot displace copper from copper(II) oxide.
Zinc + Iron(III) Oxide:
- Zinc (Zn) is more reactive than iron (Fe).
- The reaction will occur: Zinc + Iron(III) Oxide → Iron + Zinc Oxide.
- Explain the 5 factors that increase the rate of reaction
Temperature, Concentration, Surface, Catalysts, Nature.
Describe what the activation energy is
Activation energy is the minimum energy needed for a chemical reaction to proceed, acting as a barrier for reactant molecules to become products. Temperature and catalysts influence this barrier, thus impacting reaction rates.
Classify reactions as either endo or exothermic
Endothermic Reactions:
- Reactions that absorb heat energy from the surroundings.
Exothermic Reactions:
- Reactions that release heat energy to the surroundings.
Give examples of endothermic and exothermic reactions
Endothermic Reactions:
Dissolving ammonium chloride in water.
Melting ice cubes.
Evaporating liquid water.
Photosynthesis.
Exothermic Reactions:
Combustion of methane.
Neutralization of an acid with a base.
Formation of water from hydrogen and oxygen gases.
Freezing of water.
Interpret reaction profiles, calculate the delta H and determine whether the reaction is
endo/exo thermic
Reaction profiles show energy changes during a reaction. To determine if a reaction is endo/exothermic, calculate ΔH. If ΔH is positive, it’s endothermic; if negative, it’s exothermic.
Describe bond breaking as an endothermic process
Bond breaking is endothermic because it requires energy to break the attractive forces holding atoms together in a molecule. This absorbed energy makes the process endothermic.
