A full investigation written in the CXC reporting format — Part A (proposal) and Part B (implementation) — on how temperature affects the rate of reaction between sodium thiosulfate and hydrochloric acid, with the marks each section earns.
6 narrated scenes. Press play, listen and read along — the points appear as they are explained. Use ‹ Prev / Next › or the scene bar to jump to any scene.
Seeing a complete investigation from start to finish is the best way to learn what a top-mark report looks like. This one uses the famous disappearing cross.
Narration uses your device’s built-in voice. No sound? Switch to “Captions only” — the captions advance on their own.
Copy these into your notebook in your own words — that is how they stick.
Observation, hypothesis (2), aim (1), materials (1), method (2), controlled variables (1), expected results (2), assumptions/precautions (1).
Method (1), results (4), discussion (5), limitations (3), reflections (5), conclusion (2).
Manipulated: temperature; responding: time; controlled: volumes, concentrations, cross, observer.
Repeat three times; mean; rate = 1 ÷ t.
Higher temperature → more kinetic energy → more collisions with activation energy → faster reaction.
Observer judgement, cooling, temperature measured before mixing.
Refrigeration of food; industrial heating; justified adjustment.
Hypothesis supported by the data.
3 quick games on this lesson. Earn XP and badges as you play — your best score for each game is saved. Games are for practice and do not change your exam readiness. More games in the Chemistry Arcade.
8 items modelled on real CSEC Paper 1 questions. Choose one answer for each, then check. Aim for 80% or better. Work each item on paper first.
Write full answers, then reveal the mark scheme and tick the points you earned (16 marks in total). Show all your working — method marks count. Your answers are saved on this device.
Question 1 [16 marks]
Use the thiosulfate and hydrochloric acid investigation in this lesson.
(a) (a) State the hypothesis and the aim of the investigation. [3]
(b) (b) Identify the manipulated, responding and two controlled variables. [4]
(c) (c) Calculate the rate at 40 °C, given a mean time of 24 s, and compare it with the rate at 20 °C (mean time 63 s). [3]
(d) (d) Explain the trend using collision theory. [3]
(e) (e) State two limitations and one improvement. [3]
Everything in this lesson is based on these parts of the CXC syllabus and papers.