Tools
Config-driven calculators and helpers—each tool doubles as an explainer page for search and sharing. Jump into a subject hub or scroll the full catalog.
By subject
Same grouping as your curriculum—e.g. chemistry calculators in one place.
All tools
Alphabetical list of published utilities Showing 433–480 of 564.
- formula calculator
Pythagorean theorem
Hypotenuse or leg.
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Quadratic equation solver
ax² + bx + c = 0 with discriminant.
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Quantum energy levels
Hydrogen-like Bohr energies or particle-in-a-box levels.
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Quantum number checker
Validate n, l, m_l, m_s and relate to subshell capacity.
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Radical simplifier
√n = a√b for non-negative integer n.
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Rank predictor (toy)
Toy rank from an assumed percentile — not a real predictor.
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Raoult’s law calculator
Vapor pressure lowering P = X_solvent P° for ideal solutions.
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Rate law calculator
rate = k[A]^a[B]^b — solve rate, k, or a concentration.
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Ratio calculator
Simplify a : b to smallest integers.
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Reaction balance checker
Verify whether your integer coefficients and molecular formulas conserve each element (parses formulas like H2O, Ca(OH)2).
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Reaction conversion calculator
Percent conversion of a reactant from initial moles and either remaining moles or moles reacted.
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Reaction mechanism pattern guide
SN1, SN2, E1, E2 summary — not a structure-based predictor.
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Reaction order summary
Integrated laws and half-life formulas for orders 0–1–2 in [A].
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Reaction quotient Q calculator
Q from partial pressures or concentrations for aA + bB ⇌ cC + dD pattern.
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Reaction summary
Named reaction templates for organic revision.
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Reactor yield calculator
Conversion and selectivity → yield for A → P with side product.
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Reagent mixing calculator
Mix two solutions to an intermediate concentration (same solute).
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Redox electron balance (LCM)
Multipliers to match electrons between two half-reactions.
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Reflex time (toy)
path/speed + delay sketch.
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Refraction (Snell’s law)
Same as Snell’s law: n₁ sin θ₁ = n₂ sin θ₂.
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Relative velocity (1D)
v_AB = v_A − v_B on one axis.
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Resistance
R = V/I or R = ρL/A.
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Resonance (string / pipe)
String fundamental or open–open / closed–open pipe harmonics.
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Restriction enzyme finder
Search common Type II sites in DNA.
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Reverse complement
Reverse then complement DNA.
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Revision planner
Exam date and list of topics → spaced review dates.
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RMS molecular speed calculator
u_rms = √(3RT/M) with M in g/mol and T in K.
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RNA to protein translation
Standard code; stops at first stop codon.
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ROI calculator
Return on investment percent.
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Rolling motion energy
Total KE = ½mv² + ½Iω² with ω = v/R.
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Rotational kinetic energy
K = ½ I ω².
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Rounding calculator
Decimal places or significant figures.
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Safety hazard hints
GHS-style pictogram reminders from keywords (not a substitute for SDS).
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Sample dilution factor
Multiply serial dilution factors.
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Satellite motion (circular)
Period, speed, and angular speed for a circular orbit.
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Scale-up calculator
Linear geometric scale from pilot volume to plant volume.
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Scientific notation
Write a number as m × 10^n with 1 ≤ |m| < 10.
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Section formula
Internal division m : n.
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Semiconductor thermal scale
kT in eV and E_g/(kT) for order-of-magnitude reasoning.
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Sequences (AP / GP)
nth term or partial sum.
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Serial dilution factor
Multiply dilution steps.
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Series resistors
R_total = R₁ + R₂ (+ optional R₃).
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Set theory calculator
Union, intersection, difference on token sets.
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Shannon diversity
H = −Σ p ln p from species counts.
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Shear modulus
G = τ/γ.
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Shortcut tricks (roadmap)
Placeholder for curated shortcuts.
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Significant figures
Round a value to n significant figures.
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Similarity / congruence (SSS)
Compare two triangles by side lengths.
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