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MassachusettsChemistry

Module 6: Thermochemistry and kinetics

5 dot points across 5 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

How does the energy of a reaction depend on the bonds broken and formed?

Explain that breaking bonds absorbs energy and forming bonds releases it, and use bond energies to decide whether a reaction is exothermic or endothermic (MA STE HS-PS1-4, energy from changes in total bond energy).
A standard-level answer on bond energy and reaction energy for Massachusetts high school chemistry: why breaking bonds absorbs energy and forming bonds releases it, using bond energies to find the net energy change, and deciding whether a reaction is exothermic or endothermic, grounded in HS-PS1-4.
12 min answer →

What is a reaction at equilibrium, and how can we shift it to make more product?

Describe dynamic equilibrium in a reversible reaction and use Le Chatelier's principle to predict the effect of changing concentration, temperature, or pressure (MA STE HS-PS1-6(MA), shifting equilibrium to increase product).
A standard-level answer on chemical equilibrium and Le Chatelier's principle for Massachusetts high school chemistry: dynamic equilibrium in a reversible reaction and predicting the shift when concentration, temperature, or pressure changes, grounded in HS-PS1-6(MA).
13 min answer →

Why do some reactions release energy while others absorb it, and how is energy conserved?

Classify reactions as exothermic or endothermic, describe energy transfer as heat, and apply the conservation of energy to chemical and physical changes (MA STE HS-PS3-4(MA), thermal energy transfer).
A standard-level answer on energy changes in chemical reactions for Massachusetts high school chemistry: exothermic and endothermic reactions, energy transferred as heat, the conservation of energy, and the link to temperature change, grounded in HS-PS3-4(MA).
12 min answer →

How can a graph show the energy change and the energy barrier of a reaction?

Interpret a potential energy diagram to identify activation energy, the energy change of reaction, and the effect of a catalyst, and classify the reaction as exothermic or endothermic (MA STE HS-PS1-4 and HS-PS1-5, energy and rate).
A standard-level answer on potential energy diagrams and activation energy for Massachusetts high school chemistry: reading the reactant and product energy levels, the activation energy barrier, the energy change of reaction, and how a catalyst lowers the barrier, grounded in HS-PS1-4 and HS-PS1-5.
12 min answer →

What makes a reaction go faster or slower, and why?

Use collision theory to explain how temperature, concentration, surface area, and catalysts affect the rate of a reaction (MA STE HS-PS1-5, effect of temperature and concentration on reaction rate).
A standard-level answer on reaction rates and collision theory for Massachusetts high school chemistry: how collision theory explains rate, and the effects of temperature, concentration, surface area, and catalysts, grounded in HS-PS1-5.
12 min answer →