Chemistry Q&A for Class 12 · Page 2
31 free answers in Chemistry for Class 12 students, across CBSE, ICSE and State boards.
Question & Answer
Questions
- ChemistryClass 12All
What is the Ratio of Aqua Regia in NCERT
Aqua regia is prepared by mixing concentrated hydrochloric acid (HCl) and concentrated nitric acid (HNO₃) in a ratio of 3:1 by volume, meaning three parts HCl to one part HNO₃. This specific ratio creates a powerful oxidizing mixture capable of dissolving noble metals like gold and platinum that resist attack by individual acids. The name "aqua regia" translates from Latin as "royal water," reflecting its ability to dissolve gold, the "king of metals." This mixture appears in NCERT Class 10 c
- ChemistryClass 12All
How to find delta H and delta E?
These represent energy changes in chemistry and physics: ΔE (change in internal energy): ΔE = q + w q = heat added to system w = work done on system ΔH (change in enthalpy): ΔH = ΔE + Δ(PV) For reactions involving photon energy at specific frequencies: E = hf, where h is Planck's constant and f is frequency These relate to frequency when study
- ChemistryClass 12All
What is Delta T = K_f × m?
This is the freezing point depression formula: ΔT = freezing point lowering (°C) K_f = cryoscopic constant (specific to solvent) m = molality of solution (mol/kg) For boiling point elevation: ΔT = K_b × m These colligative properties depend on solute concentration, not identity.
- ChemistryClass 12All
What is delta G = -nFE?
This is the Gibbs free energy formula for electrochemical reactions: ΔG = change in Gibbs free energy (J or kJ) n = number of moles of electrons transferred F = Faraday's constant (96,485 C/mol) E = cell potential (volts) Relates electrical work to free energy change in redox reactions. Negative ΔG indicates spontaneous reaction.
- ChemistryClass 12All
What is ethyl glycol?
You likely mean ethylene glycol (C2H6O2), commonly used in antifreeze. It's a toxic diol (two -OH groups) that should never be consumed. Confusingly similar in name to ethanol, ethylene glycol poisoning is treated with ethanol because they compete for the same metabolizing enzyme. Always store antifreeze safely away from children and pets.
- ChemistryClass 12All
What is ethyl OH?
Ethyl-OH is another way of writing ethanol (C2H5OH or CH3CH2OH), where "ethyl" represents the C2H5 group and "OH" is the hydroxyl group. This notation emphasizes the alcohol functional group (-OH) attached to the ethyl chain.
- ChemistryClass 12All
What is CH3COOH pH?
CH3COOH is acetic acid (vinegar's main component). Pure acetic acid has a pH near 2.4 (very acidic), while household vinegar (5% acetic acid solution) has a pH around 2.5-3.0. pH varies with concentration—more dilute solutions have higher (less acidic) pH values.
- ChemistryClass 12All
Is there any alcohol without ethanol?
No drinkable "alcohol" beverage exists without ethanol ethanol is what makes it alcoholic. "Non-alcoholic" beers and wines contain trace amounts (usually <0.5% ethanol). If you mean other types of chemical alcohols, yes but methanol, isopropanol, and others are toxic and not for consumption.
- ChemistryClass 12All
How much methanol can a human drink?
No amount of methanol is safe to drink intentionally. As little as 10 mL (2 teaspoons) can cause blindness, and 30-100 mL can be fatal. Methanol is extremely toxic and should never be consumed. If methanol ingestion is suspected, seek emergency medical care immediately.
- ChemistryClass 12All
Is ethanol toxic to humans?
Yes, ethanol is toxic but in a dose-dependent manner. Small amounts are processed relatively safely by the body, but larger quantities overwhelm metabolic systems. Acute toxicity causes intoxication and potentially fatal poisoning, while chronic exposure damages liver, brain, heart, and other organs.
- ChemistryClass 12All
Why do farmers spray ammonia on their fields?
Farmers apply anhydrous ammonia (a concentrated liquid form) directly to soil as an efficient nitrogen fertilizer. Nitrogen is essential for plant growth and protein synthesis. This method is cost-effective and provides plants with readily available nitrogen, promoting vigorous crop growth and higher yields.