Chemical Reactions and Equations — Class 10 CBSE Science revision notes
A 5-page visual revision sheet for Chemical Reactions and Equations, written for Class 10 CBSE Science. Formulas, diagrams and the traps that cost marks, laid out to be read the night before rather than the term before. Free, and it opens inside CapCompass.
Page 1 as PDF
Chemical Reactions and Equations in one look
atoms are only rearranged, never made or lost, and the equation must show that
- Word equation: names only, nothing counted yet
- Skeletal equation: correct formulas in, atoms still unequal
- Balanced equation: every element counts the same on both sides
Signs that a chemical change has happened
- a change in state, such as wax melting and then burning to gas and vapour
- a change in colour, iron nails turning brown in copper sulphate solution
- evolution of a gas, bubbles rising when zinc meets dilute acid
- a change in temperature, the beaker turning warm or cold to the touch
- formation of a precipitate, an insoluble solid appearing in a clear solution
Balancing a chemical equation, step by step
- write the skeletal equation and box every formula so you never change what is inside a box
- count atoms of each element on both sides, listing them in a small table beside the equation
- start with the compound carrying the most atoms, and balance the element that appears in the fewest places
- leave hydrogen and oxygen for last, since they turn up in the most formulas and shift as you go
- multiply through if a fraction appears: 1/2O_2 becomes O_2 once the whole equation is doubled
- finish by adding state symbols and the conditions written over the arrow
State symbols and conditions
- solid, liquid, gas, and dissolved in water
(s) (l) (g) (aq) - heating, shown by Δ written over the arrow
CaCO_3(s) → CaO(s) + CO_2(g) - a reaction run in solution, both sides marked aq
Zn(s) + 2HCl(aq) → ZnCl_2(aq) + H_2(g)
Page 1 of 5. The full sheet, all 5 pages, opens free in the app.
What this Chemical Reactions and Equations sheet covers
- Word equation
- Skeletal equation
- Balanced equation
- Signs that a chemical change has happened
- Balanced chemical equation
- Balancing
- Balancing a chemical equation, step by step
- State symbols and conditions
- solid, liquid, gas, and dissolved in water
- heating, shown by Δ written over the arrow
- a reaction run in solution, both sides marked aq
- Combination reaction
- Decomposition reaction
- Displacement reaction
- Double displacement reaction
- Types of chemical reactions
- Combination
- Decomposition
- Displacement
- Double displacement
- Combination reactions worth knowing by name
- quicklime slaked into slaked lime, and the beaker turns hot
- whitewashing: slaked lime meets the air and a shiny film forms
- coal burning, the reaction that runs a power station
- hydrogen burning in oxygen
- Decomposition needs energy, given three ways
- Precipitation and neutralisation, both double displacement
- Displacement follows the reactivity order
- Exothermic and endothermic reactions
- Exothermic
- Endothermic
- Why some reactions need a push to start
- Redox reaction
- Oxidising agent
- Oxidation and reduction
- Redox counted in electrons
- Corrosion and rancidity
- Corrosion
- Rancidity
- Shorthand on an equation
- Traps that cost marks
- Tricks that save time
How CapCompass uses this sheet
These notes are not a standalone PDF. CapCompass plans Science chapter by chapter against your real exam dates and free hours, and when the plan reaches Chemical Reactions and Equations the sheet opens inside the study block itself — at the page covering the sub-topic that block is on, with the timer still running. Revision arrives at the moment the plan says revise, instead of having to be gone looking for.