Iron tablet titration using potassium permanganate (KMnO4). Step-by-step redox titration method to determine iron content. IB, A-level and IGCSE chemistry.
This Week in Science: Gene Therapies, Martian Storms, and the Brain’s Aging Secret
From a single injection that restores hearing to an AI system that thinks 100 times more efficiently, this week’s science stories are full of surprises. We also visit Mars, peer inside the ageing brain, watch ancient carbon spill from melting permafrost, and discover how sugarcane might save your teeth.
IBDP IA: Effect of Substrate Concentration on Catalase Activity: Michaelis-Menten Kinetics
Catalase is one of the most efficient enzymes known, breaking down hydrogen peroxide into water and oxygen at rates of up to 40 million reactions per second. In this investigation, you will measure how the rate of catalase activity changes as substrate concentration increases, generating a Michaelis-Menten curve and allowing calculation of the maximum reaction velocity (Vₘₐˣ) and the Michaelis constant (Kₘ). This is a fully quantitative IB Biology HL Internal Assessment investigation. This practical is suitable for IB Diploma Biology HL and Edexcel IGCSE Biology.
IBDP IA: Simple Pendulum: Length vs Period and Determination of g
The simple pendulum is one of the most studied systems in classical mechanics. By measuring how the period of oscillation changes with pendulum length, you can determine the local gravitational field strength g with remarkable precision from a school laboratory. The relationship T² ∝ L produces a clean linear graph whose gradient directly yields g, making this an ideal IB Physics IA for demonstrating rigorous uncertainty analysis. This practical is suitable for IB Diploma Physics HL and SL and Edexcel IGCSE Physics.
Terminal Velocity vs Sphere Radius: Verifying Stokes’ Law and Measuring Viscosity
When a sphere falls through a viscous fluid, it eventually reaches a constant velocity called terminal velocity, at which the drag force exactly balances gravity. Stokes’ law predicts that terminal velocity is proportional to the square of the sphere’s radius. By measuring terminal velocity for spheres of different radii falling through glycerol, you can verify … Continue reading Terminal Velocity vs Sphere Radius: Verifying Stokes’ Law and Measuring Viscosity
IBDP IA: Capacitor Discharge: Time Constant vs Resistance and Measurement of Capacitance
When a charged capacitor discharges through a resistor, the voltage decays exponentially with time. The time constant τ = RC determines how quickly this happens. By measuring τ for different resistance values, you can verify the linear relationship τ = RC and calculate the capacitance of the capacitor. A data logger makes this investigation particularly powerful, generating rich continuous voltage-time data for each resistance. This is an outstanding IB Diploma Physics HL Internal Assessment topic.
IBDP IA Idea: Effect of Light Wavelength on Photosynthesis Rate: Constructing an Action Spectrum
Different wavelengths of light are absorbed differently by photosynthetic pigments. By measuring the rate of photosynthesis in Elodea (Canadian pondweed) under light of different wavelengths, you can construct an action spectrum — a graph showing photosynthetic rate against wavelength — and compare it to the known absorption spectra of chlorophyll a, chlorophyll b, and carotenoids. This is an elegant and visually striking IB Biology IA.