graphs

• describing shape of graphs

  • split graph into sections
  • look x and y axis
  • as x increases what happens to Y
  • comment on gradient of line in each section
  • eg, steep shallow increasing decreasing, plateaued
  • quote data with units if possible
• comparing shape of graphs

  • look carefully at axes (rate of reaction, volume of product)
  • if it plateaus same ROR
  • or stopped reaction
  • for ROR always compared INITIAL RATE
  • comment on differences (steeper, levels off earlier)
  • quote data where possible
• explaining shape of graphs

  • for each section explain what is happening
  • so give a scientific explanation to explain the shape of each section
  • use appropriate terms (eg active site, formation of enzyme substrate complex, denstored, saturation point)
• measuring ROR

  gradient = change in y/ change in x
• equation for straight line

  y= mx + c
• m= gradient
• c= value of y when the line crosses the y axis
• measure ROR for curves

  • can be done at any point by measuring gradient
  • gradient is found by drawing tangent to the curve
• drawing a tangent to the curve

  1. position ruler at point you want to find out rate
  2. angle ruler so equal space between ruler and curve on either side
  3. draw tangent
  4. calculate the gradient of the tangent to find rate
• initial rate of reaction

  • rate right at start of the reaction
• to find initial ror

  1. have to estimate where the curve would continue if it carried below zero, draw in with pencil
  2. draw a tangent to the curve at t=0
  3. calculate the gradient of the tangent (this is the initial ROR)
  4. gradient = change in y/ change in x
  5. then work out the units of the rate (divide the units of the y axis by the units of x axis)