Built for CBSE Class XII Chemistry
Turn CBSE Class 12 Chemistry into a focused daily practice plan.
PrepAI finds your weak spots and turns them into a focused daily study plan: answer-masked retrieval, mistake repair, and board-style mocks built from review-gated content so you can learn from mistakes.
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See which Chemistry topics are costing you marks.
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See exact step marks and the line where marks were lost in 3 seconds
Click any sample response below: 5/5 Full Marks: Electrochemistry Nernst Equation, 3/5 Partial Credit: Missing Faraday Constant Unit, or 1/5 Common Exam Trap: Sign Reversal on Cell Potential.
Step-by-Step Mark Breakdown (Formula Setup +1 · Substitution +1 · Unit & Sign Check +1 · Final Numerical Answer +2)
Student Written Derivation Lines
Line 1: E_cell = E0_cell - (2.303 RT / nF) log([Zn2+] / [Cu2+])
Line 2: Substituted R = 8.314, T = 298 K, n = 2, F = 96.5 (missing C mol^-1 unit and 10^3 factor)
Line 3: Sign direction kept positive, but unit dimensional check skipped on Line 2
Line 4: E_cell = 30.65 V (decimal shifted by unscaled Faraday constant)
2 marks lost at Line 2 and Line 4: You wrote 96.5 instead of 96,487 C mol^-1 without writing the unit (C mol^-1), which threw off the final voltage decimal by a factor of 1,000.
Repair queued (3/5): Dimensional unit check drill on F = 96,487 C mol^-1 scheduled in 48 hours before your next mock.
Compare hourly private tutoring cost against 24/7 step-marked board exam practice
Select a profile (1 Subject Final Sprint, 3-Subject PCM / PCB Board Pack, or Tutoring Cohort of 25 Students) to compare traditional hourly private tutoring cost against 24/7 deterministic step-by-step rubric grading + FSRS-5 spaced-repetition scheduling.
Traditional Hourly Private Tutoring Cost
INR 48,000 / term ($580 CAD · 3 hrs/week private tutor)
PrepAI Unlimited Step-Marked Practice Model
24/7 deterministic step-by-step rubric grading + FSRS-5 spaced-repetition scheduling
Time & Cost Advantage
Save INR 42,000+ ($500+ CAD) per term with instant line-by-line marking
Wait 4 days for next tutor session vs 3-second instant step-mark feedback
Structured 7-Day Exam Recovery Plan (1 Subject Final Sprint)
Ready to copy- Day 1-2: Electrochemistry Nernst Equation & Faraday constant unit drills (10 questions/day)
- Day 3-4: Solutions van't Hoff factor & Chemical Kinetics first-order half-life step marking
- Day 5-6: d & f Block dichromate pH shifts & Coordination CFT splitting derivations
- Day 7: Timed 70-mark CBSE Class 12 Chemistry board-format mock + 48h smart retry review
See 30-day board exam retention and mark impact across study modes
Switch between Last-Minute Night Cramming, Weekly Textbook Re-Reading, and Prep AI 48h + 7d Smart Retry to compare 30-day retention and copy the high-yield CBSE Class 12 Chemistry formula sheet.
30-Day Board Exam Memory Retention
92% 30-Day Board Exam Retention
Projected CBSE Class 12 Board Mark Impact
+15 to +19 marks secured across 3-mark & 5-mark board derivations
Memory Decay & Exam-Day Outcome
FSRS-5 spaced repetition + commit-before-reveal repairs weak steps at 48 hours and 7 days right before memory decay sets in.
Automatic step-by-step recall of Formula Setup (+1), Substitution (+1), Unit & Sign Check (+1), and Final Numerical Answer (+2).
High-Yield CBSE Class 12 Chemistry Formula & Step-Mark Checklist
Ready to copy- 1. Electrochemistry (Nernst Equation): E_cell = E0_cell - (0.0591 / n) log([Anode] / [Cathode]) at 298 K | F = 96,487 C mol^-1
- 2. Solutions (Colligative Properties): Delta T_b = i * K_b * m | pi = i * C * R * T (always check van't Hoff factor i)
- 3. Chemical Kinetics (First-Order Rate): k = (2.303 / t) log([R]_0 / [R]) | Half-life t_1/2 = 0.693 / k (s^-1)
- 4. Coordination Compounds (Crystal Field): Delta_t = (4 / 9) Delta_o | Strong-field ligands (CN-, CO, en) enforce low-spin pairing
Print a 3-question repair worksheet and its step marking key for your batch
Pick a worksheet set for Electrochemistry, Chemical Kinetics, or Coordination Compounds to preview three printable questions, a five-mark step key for each, and a weekly parent WhatsApp update you fill in from checked work.
25-Student Batch | Set A: Nernst sign and unit repair
Target weak step: write the reaction quotient correctly, check the logarithm sign, and keep voltage and energy units separate.
Printable 3-Question Repair Worksheet
- Q1. For Zn(s) + Cu2+(aq) -> Zn2+(aq) + Cu(s) at 298 K, E_standard = 1.10 V, n = 2, [Zn2+] = 0.10 mol L^-1 and [Cu2+] = 1.0 mol L^-1. Treat activities as concentrations relative to 1 mol L^-1. Use E_cell = E_standard - (0.0591 V / n) log10(Q). Calculate E_cell to two decimal places. [5 marks]
- Q2. For Zn(s) + Cu2+(aq) -> Zn2+(aq) + Cu(s) at 298 K, E_standard = 1.10 V, n = 2, [Zn2+] = 1.0 mol L^-1 and [Cu2+] = 0.10 mol L^-1. Treat activities as concentrations relative to 1 mol L^-1. Use the Nernst coefficient 0.0591 V and calculate E_cell to two decimal places. [5 marks]
- Q3. For the standard Zn/Cu cell reaction Zn(s) + Cu2+(aq) -> Zn2+(aq) + Cu(s), E_standard = 1.10 V and n = 2. Using F = 96,500 C mol^-1 and 1 V C = 1 J, calculate the standard Gibbs energy change in kJ mol^-1 to one decimal place. [5 marks]
Step-by-Step Teacher Marking Key
- Q1. Formula Setup +1: E_cell = E_standard - (0.0591 V / n) log10(Q), with Q = [Zn2+] / [Cu2+]; omit pure solids.
- Q1. Substitution +1: Q = 0.10 / 1.0 = 0.10, so E_cell = 1.10 V - (0.0591 V / 2) log10(0.10).
- Q1. Unit & Sign Check +1: Q is dimensionless, log10(0.10) = -1, and subtracting the negative correction increases the voltage.
- Q1. Final Numerical Answer +2: E_cell = 1.12955 V, rounded to 1.13 V; award one mark for the calculated value and one for correct rounding.
- Q2. Formula Setup +1: E_cell = E_standard - (0.0591 V / n) log10(Q), with Q = [Zn2+] / [Cu2+].
- Q2. Substitution +1: Q = 1.0 / 0.10 = 10, so E_cell = 1.10 V - (0.0591 V / 2) log10(10).
- Q2. Unit & Sign Check +1: log10(10) = +1, so subtract 0.02955 V; the result must be below the standard voltage.
- Q2. Final Numerical Answer +2: E_cell = 1.07045 V, rounded to 1.07 V; award one mark for the calculated value and one for correct rounding.
- Q3. Formula Setup +1: Delta G_standard = -n * F * E_standard.
- Q3. Substitution +1: Delta G_standard = -2 * 96,500 C mol^-1 * 1.10 V.
- Q3. Unit & Sign Check +1: V C mol^-1 gives J mol^-1; divide by 1,000 for kJ mol^-1 and retain the negative sign for this positive standard cell voltage.
- Q3. Final Numerical Answer +2: Delta G_standard = -212,300 J mol^-1 = -212.3 kJ mol^-1; award one mark for the calculated value and one for conversion to kJ mol^-1.
Weekly Parent WhatsApp Progress Summary
Ready to copy for parent WhatsApp- Teacher draft: fill in the blanks using checked work before sharing with a parent.
- Week ending: ______. Student: ______. Worksheet completed: ______ / 3 questions. Score: ______ / 15.
- This week's focus: choosing the correct concentration ratio and checking the sign and unit in cell voltage calculations.
- Progress checked by the teacher: ______. Step still needing practice: ______.
- At home: ask your child to explain why the voltage rises in Q1 and falls in Q2 before showing the answer.
- Next check: repeat a similar question after 48 hours and again after seven days. Teacher to record the dates and results: ______.
Find the module that repairs the marks you are losing
Choose the student or teacher view, search all 17 modules, and select one to see the NCERT reference and the exact step rule it checks before you open it.
Board & JEE/NEET Score Predictor
Model possible mark gains from repairing specific chapter weaknesses.
- NCERT Reference
- NCERT learning outcomes and the selected CBSE/NTA exam syllabus.
- Sample Step Rule
- Sum verified recoverable rubric marks; label the forecast as an estimate, never a guaranteed score.
Multi-Subject PCMB & Practical Viva Step-Grader Sandbox
Choose a worked example to explore four steps worth five practice marks.
NCERT Class 11 Chemistry Laboratory Manual, Systematic Qualitative Analysis; Class 12 Chemistry, Electrochemistry: Nernst equation.
A salt solution acidified with dilute nitric acid gives a white precipitate with silver nitrate that dissolves in aqueous ammonia. Identify the anion. Separately, find E_cell at 298 K for E0_cell = 1.10 V, n = 2 and Q = 10.
- Formula/Principle Setup +1: Use the AgCl confirmation test and E_cell = E0_cell - (0.0591 V / n) log10 Q at 298 K.
- Substitution/Diagram +1: Ag+ + Cl- gives AgCl(s); E_cell = 1.10 V - (0.0591 V / 2) log10(10).
- Unit & Sign Check +1: Q is dimensionless and log10(10) = 1; Q > 1 lowers E_cell below E0_cell. Keep the answer in volts.
- Final Verified Answer +2: The anion is chloride, confirmed by white AgCl dissolving in aqueous ammonia; E_cell = 1.07045 V, approximately 1.07 V.
- Examiner Trap Warning
- Acidify with dilute HNO3, not HCl, which introduces chloride. Do not reverse the Nernst correction or use the 298 K coefficient at another temperature.
- Viva & Board Tip
- Explain that ammonia dissolves AgCl by forming a soluble diamminesilver(I) complex; distinguish the precipitate observation from the anion inference.
Answer one board question and see what to fix next
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Adjust anode [Zn2+] and cathode [Cu2+] concentrations to see live Nernst potential E_cell = 1.10 - (0.0591/2)*log10([Zn2+]/[Cu2+]).
Nernst Equation & Non-Standard Cell Potential
Calculate the cell potential E_cell at 298 K for Zn(s) | Zn2+(0.10 M) || Cu2+(0.01 M) | Cu(s) given E0_cell = 1.10 V.
Conceptual gap: Inverted reaction quotient Q. Product ion [Zn2+] (anode oxidation) belongs in the numerator and reactant ion [Cu2+] in the denominator.
How the board marks it
Step 1 (0.5 mark): Identify n = 2 electrons transferred and write Q = [Zn2+] / [Cu2+] = 0.10 / 0.01 = 10.
Step 2 (1.0 mark): Substitute into Nernst equation: E_cell = E0_cell - (0.0591 / n) * log10(Q).
Step 3 (0.5 mark): Compute E_cell = 1.10 - (0.0591 / 2) * log10(10) = 1.10 - 0.02955 = 1.070 V.
Diagnostic Score Receipt · CBSE-12-CHEM-CH2 (Electrochemistry)
Save or share this verified board-step diagnostic receipt with your parent or teacher.
Step 2 · Balance any reaction
Type a reaction or pick one below. It is balanced exactly, in your browser.
2KMnO4 + 5H2C2O4 + 3H2SO4 -> K2SO4 + 2MnSO4 + 10CO2 + 8H2O
Step 3 · The question to ask yourself next
[Conceptual Error Detected] Conceptual gap: Inverted reaction quotient Q. Product ion [Zn2+] (anode oxidation) belongs in the numerator and reactant ion [Cu2+] in the denominator. Socratic checkpoint: In the cell Zn(s) | Zn2+(0.10 M) || Cu2+(0.01 M) | Cu(s), which species is oxidized at the anode, and does its aqueous concentration sit in the numerator or denominator of Q? (Scheduled in FSRS-5 Repair Queue for 1d interval).
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Class XII Chemistry formula cards with KaTeX, units, assumptions, and common mistakes.
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