Reactions

• endothermic reaction vs exothermic reactions


  Endothermic reactions take in heat but in exothermic reactions give out heat
• Oxidation reactions is the loss of electrons, and reduction reactions is the gain of electrons.
• Redox reactions are oxidation and reduction reactions happening at the same time.
• displacement reaction Is a reaction in which a more reactive metal takes the place of a less reactive metal in a compound.
• what's the conservation of mass?

  mass of products must = mass of reactants because atoms cannot be created or destroyed.
• Word equations always take this form:

  reactants → products
• Rubidium and potassium are added to water. Predict one observation you would see that shows that rubidium is more reactive than potassium?


  When added to water, rubidium would react more vigorously than potassium, potentially producing a more violent reaction or explosion and a faster rate of hydrogen gas release.
• Sulfur is produced in the reaction.

  Why does the mixture become cloudy?


  The cloudy appearance is due to formation of sulfur which is insoluble in water.
• what is an insoluble substance?


  An insoluble substance is a substance (solid) that will not dissolve in a solvent even after mixing
• conservation of mass defenition

  mass of reactants = mass of products
• why does the conservation of mass work?


  since atoms can't be created or destroyed
• how is a salt produced?

  salt, in chemistry, is a substance produced by the reaction of an acid with a base.
• what is a neutralisation reaction?


  a chemical reaction in which an acid and base quantitatively react together to form a salt and water as products.
• what is a base?


  A base is a substance that can neutralize the acid by reacting with hydrogen ions.
• what is meant by a soluble?


  A soluble substance is one that can dissolve in a solvent, typically water, to form a solution. For example, sugar is soluble in water because it dissolves completely when mixed with it.
• what is the reaction called when Reduction and oxidation happen at the same time?

  redox reaction
• what is a reduction reaction?


  A reduction reaction is a chemical reaction in which a substance gains electrons, resulting in a decrease in its oxidation state. This process often occurs alongside oxidation, where another substance loses electrons
• what is an oxidation reaction?


  An oxidation reaction is a chemical process in which a substance loses electrons, resulting in an increase in its oxidation state. This process often occurs alongside reduction, where another substance gains those electrons
• what is a decomposition reaction?


  A decomposition reaction is a type of chemical reaction in which a single compound breaks down into two or more elements or new compounds.
• name 1 example of a decomposition reaction


  Carbonic acid: Decomposes into carbon dioxide and water at room temperature 
• what is the difference between reduction reactions and oxidation reactions?


  Oxidation: Generally involves gaining oxygen (or losing electrons).

  Reduction: Involves gaining electrons (and can involve losing oxygen).
• what is a displacement reaction?


  Displacement: A reaction where a more reactive element displaces a less reactive element from a compound
• Complete combustion is...


  is a chemical reaction that occurs when a fuel burns in the presence of sufficient oxygen, resulting in the production of carbon dioxide (CO₂) and water (H₂O) as the primary products. This type of combustion releases a significant amount of energy, typically in the form of heat and light.(methane + oxygen = carbon dioxide + water).
• incomplete combustion is...

  when a fuel burns in insufficient oxygen, resulting in the production of carbon monoxide (CO), soot (carbon), and other potentially harmful substances, along with carbon dioxide (CO₂) and water (H₂O). This type of combustion is less efficient than complete combustion and can release less energy. (Fuel + oxygen → carbon monoxide + water.)
• name a combustion reaction


  fire is a combustion reaction
• why is incomplete combustion dangerous?


  Carbon monoxide (co) is a poisonous gas as it reduces oxygen carrying capacity of our blood, when inhaled. it is called the silent killer and is found in boilers in households.
• Explain how changing the concentration of sodium thiosulfate affects the rate of reaction in this experiment. (rate of reaction required practical)


  Increasing the concentration of sodium thiosulfate increases the rate of reaction. This is because a higher concentration means more sodium thiosulfate particles are present in the solution, so there are more collisions between the sodium thiosulfate molecules and the hydrochloric acid molecules. As a result, the frequency of successful collisions increases, speeding up the formation of sulfur and making the solution cloudier more quickly.
• What is ammonium chloride's state at room temperature?

  It is a white solid
• What happens to ammonium chloride when heated?

  It breaks down into ammonia and hydrogen chloride
• Write the balanced equation for the breakdown of ammonium chloride.

  NH$_4$Cl(s) ⇌ NH$_3$(g) + HCl(g)
• What happens to hydrated copper sulfate when heated?

  It loses water and becomes anhydrous
• to measure a fixed volume, what apparatus would you use?

  A volumetric pipette is used
• name 2 observations made when potassium reacts with water

  lilac flame, potassium starts to float in water.
• explain why calcium reacts more vigorously than magnesium with hydrochloric acid?

  calcium atoms are larger than a magnesium atom, meaning it has more shells, this means that the outer shell of calcium is less electrostatically attracted to the nucleus than magnesium meaning it is easier to lose an electron for calcium.
• acid and metals half equations and word equation

  metal + acid ----> salt + hydrogen

  2H+ + 2e -> H2
• What is the mash analogy

  Metal + Acid —> salt + hydrogen
• copper carbonate + sulfuric acid ->

  Copper carbonate + sulfuric acid → Copper sulfate + Water + Carbon dioxide
• Acid + Metal → Salt + Hydrogen

  Example: Magnesium + Hydrochloric acid → Magnesium chloride + Hydrogen
• Metal + Oxygen → Metal Oxide

   Example: Magnesium + Oxygen → Magnesium oxide
• Acid + Base → Salt + Water (Neutralisation)

  Example: Hydrochloric acid + Sodium hydroxide → Sodium chloride + Water