Changing Temperature

11SCI - Chemical Tūhura

Finn LeSueur


Investigating a Change in Temperature

  • To measure the effect of temperature on the rate of reaction between sodium thiosulphate and hydrochloric acid
  • To consider fair testing and accuracy in my method
  • To justify why increasing the temperature increases the rate of reaction

Reaction of Sodium Thiosulphate and \(HCl\)

  • On Thursday you will be reacting these chemicals together. Sodium thiosulphate has chemical symbol \(Na_{2}S_{2}O_{3}·5H_{2}O\) and hydrochloric acid \(HCl\).
  • Both are clear liquids and when mixed together the solution goes cloudy over a period of time.
  • By measuring the time until the black cross is no longer visible, you can determine the relative rate of reaction.

The Setup

Thiosulphate & HCl

Whakamātau Groups


Step 1: Aim & Hypothesis

In your group:

  1. Title your whakamātau
  2. Come up with an aim (what are you investigating; be specific)
  3. Come up with a hypothesis (what do you predict; be specific)

Step 2: Variables

  • Independent Variable: The variable that you will change. What are we changing? Include units, measurement apparatus & range of measurements.
  • Dependent Variable: The variable being measured. What are you measuring? Include units & measurement apparatus.

Step 3: Control Variables & Reliability

  • Control Variable: Things that you are keeping constant. What will you not change throughout your whakamātau?
  • Reliability: An whakamātau is reliable if the results are within x seconds of each other when the method is repeated. The same method must give the same results each time.

Step 4: Method

  • Give you method as a numbered list,
  • List what equipment you will need (e.g. a 100ml beaker; 25ml of diluted \(HCl\)),
  • Break things up into small steps and say when you repeat a set of steps,

Step 4: Continued

  • State your range of measurement for your independent variable, its units and how you will measure it,
  • States some control variables and how to control them during the whakamātau.

Step 5: Data/Results

  • Design a table to record your results before you start the whakamātau,
  • You will need to think about how many trials you are going to do, how many measurements you will make and calculating an average.
Trial 1 Trial 2 Trial 3 Average
Temp 1 (\(10^{\circ}C\))
Temp 2 (\(20^{\circ}C\))
Temp 3 (\(30^{\circ}C\))
Temp 4 (\(40^{\circ}C\))