temperature changes rp

• what is an exothermic reaction?


  when energy is released into the surroundings
• what is an endothermic reaction?


  when energy is taken in from the surroundings.
• what is the practical investigating?


  temperature change in an exothermic reaction - neutralisation reaction between hydrochloric acid and the alkali sodium hydroxide
• what happens during the practical?

  increasing volumes of sodium hydroxide are added to hydrochloric acid - ensuring in each experiment the maximum temperature is reached.
• what is the independent variable in the practical?


  the volume of sodium hydroxide solution.
• what is the dependant variable in the practical?


  the maximum temperature reached.
• what are the control variables of in the practical?


  volume of hydrochloric acid, the concentrations of both the hydrochloric acid and the sodium hydroxide solution.
• what is the first step of the practical?

  use a measuring cylinder to measure 30cm^3 of dilute hydrochloric acid.
• what should be done after measuring the dilute hydrochloric acid?


  transfer the acid into a polystyrene cup and stand it in a beaker to stop it from falling over.
• what is the third step of the practical?


  use a thermometer to measure the temperature of the acid - record in a table
• how much sodium hydroxide solution is measured out and how?


  5cm^3 in a measuring cylinder - then transfer to a polystyrene cup
• what should also be used?

  a lid
• why is the cup made out of polystyrene?


  to keep heat in
• why is the polystyrene cup in a beaker?


  for stability so it doesn’t tip
• what things should stay the same? (control variable)


  volume of liquid, concentration of acid, mass of metals, surface area of metals
• what do you measure?

  maximum temperature rise
• independent variable 


  variable that is altered through the experiment
• dependant variable 


  variable being tested or measured in an experiment
• conttoo variable


  variable that stays the same throughout an experiment