required prac 4

• Investigating the variables that affect temperature changes and chemical reactions

  1. Measure the maximum temperature reached in an exothermic neutralization reaction between hydrochloric acid and sodium hydroxide

  2. Use a measuring cylinder to measure 30 cm3 of dilute hydrochloric acid

  3. Transfer the acid into a polystyrene cup

  4. Stand the polystyrene cup inside a beaker

  5. Measure the temperature of the acid using a thermometer

  6. Measure 5 cm3 of sodium hydroxide solution using a measuring cylinder and transfer it to the polystyrene cup

  7. Fit a plastic lid to the cup and place the thermometer through the hole in the lid

  8. Gently stir the solution

  9. Record the highest temperature reached

  10. Repeat the experiment using increasing volumes of sodium hydroxide solution (10 cm3, 15 cm3, etc. up to 40 cm3)

  11. Calculate the mean maximum temperature reached for each volume of sodium hydroxide solution

  12. Plot a graph of the results
• Exothermic reaction


  • Releases energy
  • Temperature of the solution increases
• Independent variable


  • Volume of sodium hydroxide solution
• Dependent variable


  • Maximum temperature reached
• Control variables


  • Volume of hydrochloric acid
  • Concentrations of hydrochloric acid and sodium hydroxide solution
• Increasing the volume of sodium hydroxide solution

  Increases the maximum temperature reached
• Adding large volumes of sodium hydroxide solution

  Maximum temperature reached decreases
• Polystyrene cup with a lid is used to reduce heat loss
• the reaction between hydrochloric acid and magnesium is exothermic
• Magnesium ribbon is added to the test tube containing hydrochloric acid.
• when the reaction between hydrochloric acid and magnesium occurs, it produces heat energy which causes the water to boil
• The reaction between hydrochloric acid and magnesium can be represented by the equation: 2HCl(aq) + Mg(s) → H2O(l) + Cl2(g) + MgCl2(aq)
• Exothermic reaction


  A reaction that releases heat into the surroundings, causing an increase in temperature