temperature changes

• what is the independent variable?

  sodium hydroxide solution
• what is the dependent variable?

  the maxiumum temperature reached
• what are the control variables?

  volume of hydrochloric acid and concentrations of both the hydrochloric acid and sodium hydroxide solution
• 1. use measuring cylinder to measure 30cm3 of dilute hydrochloric acid and transfer into polystyrene cup.
• 2) we place the polystyrene cup inside a beaker ; why?


  to stop it from falling over
• 3) use thermometer to record temperature of acid and record on a table.
• 4) use measuring cylinder to measure 5cm3 of hydroxide solution and transfer to polystyrene cup.
• 5) fit a plastic lid on cup and place thermometer through the hole - gently stir solution.
• 6) look for temperature rise - when it stops rising we record the highest temperature reached.
• 7) repeat experiment 7 more times and rise sodium hydroxide solution by 5cm3.
• as we increase the volume of sodium hydroxide solution , the maximum temperature increases
• why do we use a polystyrene cup with a lid?

  reduce any heat losses and polysterne is a good thermal insulator.