c6 rates of reaction

• Investigating the effect of SA on rate of reaction - METHOD

  1. Place an empty conical flask on a top pan balance, press zero
  2. Keep flask on balance and measure out 5g of marble chips into the flask
  3. Place cotton wool into the neck of the flask
  4. Measure 25cm^3 of HCl using a measuring cylinder and add to conical flask
  5. Start stopwatch and record mass every 20 seconds until there is no change
  6. Repeat using differently sized marble chips
• Investigating the effect of SA on rate of reaction

  • Reactants - calcium carbonate marble chips , hydrochloric acid
  • Products - calcium chloride, water, carbon dioxide
• Investigating the effect of SA on rate of reaction - RESULTS

  • Small marble chips had the fastest rate of reaction
  • So they have the largest SA and this proves that larger SA = faster rate
  • Larger marble chips had the slowest rate of reaction
  • So they have the smallest SA therefore a slower rate
• How and why does the rate of reaction change during the reaction of calcium carbonate with HCl?

  • Acid particles are used up
  • So SA and conc will decrease
  • And there are less frequent collisions
  • So the rate of reaction decreases
• Investigating the effect of concentration on rate of reaction - observing colour change METHOD

  1. Use a measuring cylinder to put 50cm^3 of 0.01M sodium thiosulfate solution into a conical flask
  2. Put flask on a black cross
  3. Put 10cm^3 of hydrochloric acid (from conc 0.5-2.5M) into measuring cylinder
  4. Add acid to flask and start stopwatch
  5. Swirl flask gently and look through the top of flaks until you can no longer see the cross, then stop the stopwatch
• Investigating the effect of conc on rate of reaction - observing colour change ANALYSIS

  • Reactants = sodium thiosulfate solution, hydrochloric acid
  • Products = sodium chloride, water, sulfur dioxide, sulfur
  • Solution went CLOUDY because a precipitate formed (sulfur)
  • Repeatable because it's your judgement only
  • Not reproducible because colour change is subjective
• Investigating the effect of concentration on rate of reaction - measuring volume of gas produced METHOD

  1. Measure 50cm^3 of 2M HCl into a conical flask using a measuring cylinder
  2. Add a 3cm strip of magnesium ribbon into the conical flask and place a gas syringe into the top (make sure it's at zero)
  3. Start stopwatch and record volume of hydrogen given off every 10 seconds in a table
  4. Continue timing until no more gas is given off
  5. Repeat steps using 1.5M HCl
  6. Plot a graph showing results
• Investigating the effect of conc on rate of reaction - potential errors

  • Measurement error - misreading measurement, human error in taking measurement
  • Random error - correct by repeating experiment and calculating a new mean
  • Systematic error - error with equipment, correct by using a different method or different equipment
  • Zero error - false reading, corrected by pressing zero before measuring, setting gas cylinder to zero