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Practical Chemistry Formula Sheet

All key Practical Chemistry formulas, titration relations, n-factors, group reagents, flame tests and confirmatory reactions for JEE Main & Advanced quick revision.

8 min read Updated Jun 2026 #formula sheet#quick revision#jee-main

One-page rapid revision of every must-know relation, group reagent, indicator, n-factor and confirmatory reaction from Qualitative and Volumetric Analysis. Use it the night before the exam.

How to read this sheet
This chapter is mostly observation- and reaction-based, so the sheet blends a small number of quantitative formulas (titration relations, n-factors, concentration) with high-yield reaction equations, group reagents and confirmatory tests. Everything here is drawn directly from the chapter pages.

Volumetric Analysis: Core Relations

Titration master equations

$$\boxed{N_1 V_1 = N_2 V_2}$$$$\boxed{\dfrac{M_1 V_1}{n_1} = \dfrac{M_2 V_2}{n_2}}$$

For reactants of equal n-factor this reduces to $M_1 V_1 = M_2 V_2$.

QuantityFormulaNotes
Normality$N = M \times n$n = n-factor (valence factor)
Equivalence condition$N_1 V_1 = N_2 V_2$milliequivalents equal at end point
General balance$\dfrac{M_1 V_1}{n_1} = \dfrac{M_2 V_2}{n_2}$use when n-factors differ
Milliequivalents$\text{meq} = M \times V \times n = N \times V$V in mL
Equivalent mass$E = \dfrac{\text{Molar mass}}{n}$
Mass of pure substance$\text{mass} = \text{meq} \times E \times 10^{-3}$meq in mL-based units
Equivalence point vs End point
Equivalence point = reaction stoichiometrically complete. End point = indicator changes colour. Choose the indicator so the two coincide.

Concentration and purity

QuantityFormula
Molarity$M = \dfrac{\text{mass}}{\text{molar mass} \times V_{(\text{L})}}$
Moles$n = M \times V_{(\text{L})}$
Percentage purity$\%\,\text{purity} = \dfrac{\text{mass of pure compound}}{\text{mass of sample}} \times 100$

Worked example from the chapter: $0.04\ \text{M}$ oxalic acid from $1.26\ \text{g}$ of $\ce{H2C2O4.2H2O}$ in $250\ \text{mL}$ uses $M = \dfrac{1.26}{126 \times 0.25} = 0.04\ \text{M}$.

n-Factors (Valence Factors)

The single most error-prone step in titration sums.

SpeciesHalf-changen-factor
HCl1 replaceable $\ce{H+}$1
$\ce{H2SO4}$2 replaceable $\ce{H+}$2
$\ce{H3PO4}$3 replaceable $\ce{H+}$ (full neutralisation)3
NaOH1 $\ce{OH-}$1
$\ce{Ca(OH)2}$2 $\ce{OH-}$2
$\ce{Al(OH)3}$3 $\ce{OH-}$3
$\ce{KMnO4}$ (acidic)Mn: $+7 \to +2$5
$\ce{K2Cr2O7}$Cr: $+6 \to +3$, 2 atoms6
$\ce{Fe^2+}$$\ce{Fe^2+ -> Fe^3+}$1
Oxalic acid $\ce{H2C2O4}$C: $+3 \to +4$, 2 atoms2
$\ce{I2}$$\ce{I2 + 2e- -> 2I-}$2
$\ce{Na2S2O3}$$\ce{2S2O3^2- -> S4O6^2- + 2e-}$1
$\ce{H2O2}$ (reductant)O: $-1 \to 0$, 2 atoms2

Redox rule: $n = (\text{change in oxidation number}) \times (\text{number of atoms changing})$.

Acid-Base Titrations

Neutralisation

$$\ce{H+ + OH- -> H2O}$$

Indicator selection

IndicatorpH rangeColour change (acid → base)Best for
Methyl orange3.1 – 4.4Red → Orange/YellowStrong acid + Weak base
Methyl red4.2 – 6.3Red → YellowStrong acid + Weak base
Bromothymol blue6.0 – 7.6Yellow → BlueStrong acid + Strong base
Litmus4.5 – 8.3Red ↔ BlueApproximate only
Phenolphthalein8.3 – 10.0Colourless → PinkWeak acid + Strong base
Titration typeEquivalence-point pHIndicator
Strong acid + Strong base7Any
Weak acid + Strong base> 7 (8–9)Phenolphthalein
Strong acid + Weak base< 7 (5–6)Methyl orange / red
Weak acid + Weak base≈ 7 (variable)No sharp indicator
Memory hooks
“Phenol Prefers basic” → phenolphthalein for weak acid + strong base. “Methyl in the Middle/acidic” → methyl orange / red for strong acid + weak base.

Key acid-base reactions

$$\ce{HCl + NaOH -> NaCl + H2O}$$

$$\ce{CH3COOH + NaOH -> CH3COONa + H2O}\quad(\text{eq. pt. pH} > 7)$$

$$\ce{HCl + NH4OH -> NH4Cl + H2O}\quad(\text{eq. pt. pH} < 7)$$

$$\ce{H2C2O4 + 2NaOH -> Na2C2O4 + 2H2O}$$

$$\ce{H2SO4 + 2NaOH -> Na2SO4 + 2H2O}$$

Redox Titrations

Reduction half-reactions (acidic medium)

$$\boxed{\ce{MnO4- + 8H+ + 5e- -> Mn^2+ + 4H2O}}\quad n = 5$$$$\boxed{\ce{Cr2O7^2- + 14H+ + 6e- -> 2Cr^3+ + 7H2O}}\quad n = 6$$$$\ce{I2 + 2e- -> 2I-}\quad n = 2$$

Standard titration reactions

TitrationBalanced reaction
KMnO₄ vs Fe²⁺$\ce{MnO4- + 8H+ + 5Fe^2+ -> Mn^2+ + 5Fe^3+ + 4H2O}$
KMnO₄ vs oxalic acid$\ce{2MnO4- + 5H2C2O4 + 6H+ -> 2Mn^2+ + 10CO2 + 8H2O}$
KMnO₄ vs H₂O₂$\ce{2MnO4- + 5H2O2 + 6H+ -> 2Mn^2+ + 5O2 + 8H2O}$
K₂Cr₂O₇ vs Fe²⁺$\ce{Cr2O7^2- + 14H+ + 6Fe^2+ -> 2Cr^3+ + 6Fe^3+ + 7H2O}$
Iodometry (Cu²⁺)$\ce{2Cu^2+ + 4I- -> 2CuI v + I2}$
Thiosulfate titration$\ce{I2 + 2S2O3^2- -> 2I- + S4O6^2-}$
TitrantMediumIndicatorColour change
KMnO₄dil. $\ce{H2SO4}$self-indicatorpurple → colourless (faint pink end point)
K₂Cr₂O₇dil. $\ce{H2SO4}$diphenylamine / ferricyanideorange → green
I₂ / iodometry—starch (add near end point)blue-black → colourless
Why dil. H2SO4 (not HCl/HNO3) for KMnO4
$\ce{HCl}$: $\ce{Cl-}$ is oxidised by $\ce{MnO4-}$ ($\ce{2MnO4- + 16H+ + 10Cl- -> 2Mn^2+ + 5Cl2 + 8H2O}$), consuming extra titrant. $\ce{HNO3}$: itself an oxidiser. $\ce{SO4^2-}$ is stable — no interference.
High-yield reasoning facts
KMnO₄–oxalic acid is autocatalysed by $\ce{Mn^2+}$, so heat oxalic acid to 60–70 °C (never boil — it decomposes). Fe²⁺ is NOT heated (avoids aerial oxidation $\ce{4Fe^2+ + O2 + 4H+ -> 4Fe^3+ + 2H2O}$). Add starch only near the iodometric end point.

Mohr’s salt relation

Mohr’s salt $\ce{FeSO4.(NH4)2SO4.6H2O}$, molar mass $= 392\ \text{g/mol}$ (contains one $\ce{Fe^2+}$). Volume of $0.02\ \text{M}$ KMnO₄ for mass $m$ g:

$$\boxed{V = \dfrac{1000\,m}{39.2} \approx 25.5\,m\ \text{mL}}\qquad m = 0.0392\,V\ \text{g}$$

Qualitative Analysis: Cation Groups

GroupReagentCationsPrecipitate / note
0none (test directly)$\ce{NH4+}$$\ce{NH3}$ gas
Idil. HCl$\ce{Ag+,\ Pb^2+,\ Hg2^2+}$$\ce{AgCl,\ PbCl2,\ Hg2Cl2}$ (white)
II$\ce{H2S}$ / acidic (dil. HCl)$\ce{Hg^2+,\ Pb^2+,\ Bi^3+,\ Cu^2+,\ Cd^2+}$; $\ce{As^3+,\ Sb^3+,\ Sn^4+}$sulfides
III$\ce{NH4OH + NH4Cl}$$\ce{Fe^3+,\ Al^3+,\ Cr^3+}$hydroxides
IV$\ce{H2S}$ / basic$\ce{Co^2+,\ Ni^2+,\ Mn^2+,\ Zn^2+}$sulfides
V$\ce{(NH4)2CO3}$$\ce{Ba^2+,\ Sr^2+,\ Ca^2+}$carbonates
VInone (stay in solution)$\ce{Mg^2+,\ Na+,\ K+}$—

Why groups separate: H₂S and Ksp

$$\ce{H2S <=> H+ + HS-}\quad K_{a1} = 1\times10^{-7}$$

$$\ce{HS- <=> H+ + S^2-}\quad K_{a2} = 1\times10^{-14}$$

$$\ce{H2S <=> 2H+ + S^2-}\quad K_a = K_{a1}K_{a2} = 10^{-21}$$$$\boxed{[\ce{S^2-}] = \dfrac{K_a\,[\ce{H2S}]}{[\ce{H+}]^2} \quad\Rightarrow\quad [\ce{S^2-}] \propto \dfrac{1}{[\ce{H+}]^2}}$$

Acidic medium ⇒ low $[\ce{S^2-}]$ ⇒ only low-Ksp Group II sulfides precipitate. Basic medium ⇒ high $[\ce{S^2-}]$ ⇒ higher-Ksp Group IV sulfides also precipitate.

Group II sulfides (low Ksp)Group IV sulfides (higher Ksp)
$\ce{HgS}\ 10^{-54}$, $\ce{CuS}\ 10^{-36}$$\ce{ZnS}\ 10^{-23}$, $\ce{NiS}\ 10^{-21}$
$\ce{CdS}\ 10^{-29}$, $\ce{PbS}\ 10^{-28}$$\ce{CoS}\ 10^{-21}$, $\ce{MnS}\ 10^{-15}$

Flame Tests

CationFlame colourNote
$\ce{Na+}$Golden yellowvery persistent; 589 nm (3p → 3s)
$\ce{K+}$Lilac / violetview through cobalt-blue glass (absorbs Na yellow)
$\ce{Ca^2+}$Brick red
$\ce{Sr^2+}$Crimson reddeeper than Ca
$\ce{Ba^2+}$Apple greenpersistent
$\ce{Cu^2+}$Bluish green
$\ce{Pb^2+}$Bluefaint, brief
$\ce{Li+}$Crimson

Bead and Cavity Tests

Borax bead

$$\ce{Na2B4O7 ->[\Delta] 2NaBO2 + B2O3}$$

$$\ce{B2O3 + CoO -> Co(BO2)2}\ (\text{coloured})$$
IonOxidising flameReducing flame
$\ce{Cu^2+}$blue-greenred/brown (opaque)
$\ce{Fe^3+}$yellow-brown (hot)bottle green
$\ce{Co^2+}$blue (both)blue (both)
$\ce{Cr^3+}$green (both)green (both)
$\ce{Mn^2+}$violetcolourless

Charcoal cavity (with $\ce{Na2CO3}$, reducing)

ObservationMetal
White encrustation, yellow when hot$\ce{Zn^2+}$ (ZnO)
Grey metallic bead$\ce{Pb^2+,\ Sn^2+}$
Red/brown bead$\ce{Cu^2+}$
Yellow encrustation$\ce{Cd^2+,\ Pb^2+}$
Garlic smell$\ce{As^3+}$

Anion Confirmatory Tests

AnionTestKey reaction / observation
$\ce{CO3^2-}$dil. acid$\ce{CO3^2- + 2H+ -> CO2 ^ + H2O}$; lime water $\ce{CO2 + Ca(OH)2 -> CaCO3 v + H2O}$
$\ce{SO4^2-}$$\ce{BaCl2}$$\ce{SO4^2- + Ba^2+ -> BaSO4 v}$ (white, insoluble in dil. HCl)
$\ce{Cl-}$$\ce{AgNO3}$$\ce{Cl- + Ag+ -> AgCl v}$; dissolves in dil. $\ce{NH3}$: $\ce{AgCl + 2NH3 -> [Ag(NH3)2]+ + Cl-}$
$\ce{Br-}$$\ce{AgNO3}$$\ce{Br- + Ag+ -> AgBr v}$ (pale yellow), sparingly sol. in dil. $\ce{NH3}$
$\ce{I-}$$\ce{AgNO3}$$\ce{I- + Ag+ -> AgI v}$ (yellow), insoluble even in conc. $\ce{NH3}$
$\ce{NO3-}$brown ring$\ce{NO3- + 4H+ + 3Fe^2+ -> 3Fe^3+ + NO ^ + 2H2O}$
$\ce{S^2-}$dil. acid$\ce{S^2- + 2H+ -> H2S ^}$; $\ce{H2S + Pb^2+ -> PbS v + 2H+}$ (black)
$\ce{CH3COO-}$dil. $\ce{H2SO4}$ + ester test$\ce{CH3COOH + C2H5OH ->[H2SO4] CH3COOC2H5 + H2O}$ (fruity)
$\ce{PO4^3-}$ammonium molybdate + $\ce{HNO3}$canary-yellow $\ce{(NH4)3PO4.12MoO3}$
$\ce{C2O4^2-}$$\ce{CaCl2}$$\ce{C2O4^2- + Ca^2+ -> CaC2O4 v}$ (white)

Brown ring complex

$$\ce{[Fe(H2O)6]^2+ + NO -> [Fe(H2O)5NO]^2+ + H2O}$$

The brown $\ce{[Fe(H2O)5NO]^2+}$ ring forms at the layer junction; conc. $\ce{H2SO4}$ (d = 1.84) supplies the dense lower layer and the $\ce{H+}$ for reduction.

Cation Confirmatory Tests

CationReagentResult
$\ce{NH4+}$Nessler’s $\ce{K2[HgI4]}$brown ppt
$\ce{Pb^2+}$hot water (PbCl₂ soluble) then $\ce{K2CrO4}$$\ce{Pb^2+ + CrO4^2- -> PbCrO4 v}$ (yellow)
$\ce{Ag+}$$\ce{NH4OH}$ then $\ce{HNO3}$$\ce{AgCl}$ dissolves then reforms (white)
$\ce{Cu^2+}$excess $\ce{NH4OH}$$\ce{Cu^2+ + 4NH3 -> [Cu(NH3)4]^2+}$ (deep blue)
$\ce{Cu^2+}$$\ce{K4[Fe(CN)6]}$$\ce{Cu2[Fe(CN)6] v}$ (reddish brown)
$\ce{Fe^3+}$$\ce{K4[Fe(CN)6]}$$\ce{Fe4[Fe(CN)6]3 v}$ (Prussian blue)
$\ce{Fe^3+}$$\ce{KSCN}$$\ce{[Fe(SCN)]^2+}$ (blood red)
$\ce{Al^3+}$excess NaOH$\ce{Al(OH)3 + OH- -> [Al(OH)4]-}$ (amphoteric, dissolves)
$\ce{Zn^2+}$excess NaOH$\ce{Zn(OH)2 + 2OH- -> [Zn(OH)4]^2-}$ (dissolves)
$\ce{Mg^2+}$NaOH$\ce{Mg(OH)2 v}$ (insoluble in excess — not amphoteric)
$\ce{Na+}$pyroantimonate$\ce{Na[Sb(OH)6] v}$ (white)
$\ce{K+}$cobaltinitrite$\ce{K3[Co(NO2)6] v}$ (yellow)

Distinguishing Fe²⁺ from Fe³⁺

Test$\ce{Fe^2+}$$\ce{Fe^3+}$
Colourpale greenyellow/brown
$\ce{K3[Fe(CN)6]}$Prussian/Turnbull’s blue pptno ppt
KSCNno colourblood red
NaOHdirty green $\ce{Fe(OH)2}$reddish-brown $\ce{Fe(OH)3}$
Amphoteric vs not
$\ce{Zn(OH)2}$ and $\ce{Al(OH)3}$ dissolve in excess NaOH (amphoteric); $\ce{Mg(OH)2}$ does not. $\ce{Zn(OH)2}$ also dissolves in excess $\ce{NH4OH}$ (forms $\ce{[Zn(NH3)4]^2+}$) but $\ce{Al(OH)3}$ does not — the quick Zn vs Al discriminator.

Apparatus Quick Facts

ItemRinse withKey point
Burettetitrantleast count 0.1 mL; read meniscus bottom; remove air bubbles & funnel
Pipetteanalytetransfers accurate fixed volume
Conical flaskdistilled water onlydilution does not change moles of analyte
Last-minute reminders

Rinse burette/pipette with their own solution, conical flask with water only.

KMnO₄ is a self-indicator; K₂Cr₂O₇ needs an external one.

“Brown fumes → NO₂ → nitrate” on dry heating.

$\ce{BaSO4}$ insoluble in dil. HCl confirms both $\ce{Ba^2+}$ and $\ce{SO4^2-}$.

Keep going in this chapter

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