CC14

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  • C14a
    • rates of reaction
      • you can change the rate of reaction by changing variables
        • size of pieces of solid reactant used
        • concentration of solutions
      • we can measure the rate of reaction by checking the volume of mass of the reactants
        • FOR EXAMPLE
          • THE CHANGE IN RATE OF REACTIONS BETWEEN MAGNESIUM STRIPS AND GRANULES REACTION WITH SULPHURIC ACID
            • USE A GAS SYRINGE TO MEASURE THE AMOUNT OF GAS ESCAPING - THIS WAY NONE IS LOST AS THERE IS A BUNG PREVENTING IT
          • WE CAN SEE THE RATE OF REACTION IS FASTER FOR THE GRANULES AS THE GRAPH LINE IS STEPPER
            • THIS HAPPENS BECAUSE THE GRANULES ARE SMALLER PIECES THAN THE STRIPS
            • OR
              • PUT THE CONICAL FILLED WITH CALCIUM CARBONATE AND HYDROCHLORIC ACID ON A WEIGHING SCALE
              • AS IT'S MASS DECREASES WE KNOW CO2 IS ESCAPING SHOWING A REACTION IS OCCURING
      • the steeper the line on a graph the faster the rate of reaction (REFER TO GRAPH ON PG. 250)
    • factors that affect rate of reaction
      • activation energy is the amount of energy needed for there to be a successful collision
        • a successful collision occurs when to particles hit each other with enough energy and the right orientation to break others bonds so they can rearrange to form and new substance
      • higher the frequency (no. of collisions in a certain amount of time)
      • and higher the energy (no, of particles that have the right amount of activation energy) more reactions occur
      • and high temp. affect rate of reaction
        • high pressure of gases
          • large surface area
            • how high concentration
              • increases RoR - there are more particles to react with so collisions occur more frequently
            • the particles can access more parts of the substance meaning more collisions and higher rate of reaction
          • increases rate of reaction because more particles are squeezed closer together meaning bigger chance they collide
        • increases rate of reaction as gives reactant particles more energy and so they speed up and collide more often
          • Untitled
      • CORE PRATICAL
        • METHOD
          • 1. PLACE MARBLE CHIPS IN A BEAKER WITH A PIECE OF PAPER WITH A CROSS UNDER-NEATH
            • 2. ADD THE DILUTE HYDRO-CHLORIC ADIC
              • 3. TIME HOW LONG IT TAKES FOR THE CROSS TO NO LONGER BE VISIBLE
                • REPEAT WITH POWDER AND SMALL MARBLE CHIPS
    • catalysts affect on rate of reaction
      • catalysts are substances that speed up a rate of reaction without being changed themselves or effecting the product of that reaction
      • catalysts are useful in business because it means high temps aren't needed and reaction occur faster - they are also not used up
        • catalysts lower the activation energy meaning particles require less energy for a reaction to occur
          • refer to graph on pg. 257 - it shows us that the overall energy change is the same but the catalyst just lowers the activation energy
            • Ea - activation energy            Ec - activation energy with catalyst
          • you know enzymes - large protein molecules which have a specific active site nd if temp gets too high they denature no longer have specific active site
  • Conclusion: the powder and the small marble chips have faster reactions as they have a larger surface area

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