Chemistry imp questions

• Calculate the percent (%) composition of hydrogen and oxygen in water
• Molecular formula of water: H2O
• % of oxygen = (Mass of Oxygen / Molecular mass of H2O) x 100 = 88%
• % of Hydrogen = (Mass of Hydrogen / Molecular mass of H2O) x 100 = 11%
• A compound contains 4.07% hydrogen, 24.27% carbon, and 71.65% oxygen
• Empirical formula = CH2Cl
• Molecular formula = C2H4Cl2
• What is limiting reagent?
• A reactant completely consumed in a chemical reaction
• State Law of conservation of mass
• Matter can be neither created nor destroyed
• State Law of constant or definite proportion
• A chemical compound always contains the same elements combined together in the same proportion by mass
• Express 0.002568 in scientific notation
• 0.002568 = 2.58 x 10^-3
• If the mass of one molecule of water is 18 amu, what is the mass of one mole of water
• 18 grams
• Calculate the mass of CaO and CO2 produced on complete decomposition of 5.0 g of CaCO3
• Mass of CaO = 2.8 g
• Mass of CO2 = 2.2 g
• Calculate the mass of ammonia produced if 2 x 10^3 g dinitrogen reacts with 1 x 10^3 g of dihydrogen
• Mass of ammonia produced = 2428.57 g
• State Gay Lussac’s law of combining volumes
• When gases combine, they do so in volumes that bear a simple ratio to each other and to the product formed
• Write the postulates of Dalton’s atomic theory
• Atoms of different elements combine in a fixed ratio to form compounds
• What is empirical formula? Give one example of a compound whose empirical and molecular formula are the same
• Empirical formula is the simplest whole number ratio of various atoms present in a compound
• Example: H2O
• If 120 g of propane is burnt in excess of oxygen, how many grams of water are formed?
• 196.36 g of water
• Calculate the mole fraction of ethanol in a solution containing 20 g of ethanol and 100 g of water
• Mole fraction of ethanol = 0.07
• Name any two lifesaving drugs
• 1. Cisplatin

  2. Taxol
• Define molar volume. What is its value at STP?
• Volume occupied by one mole of any gas at STP is called molar volume
• Molar volume at STP is 22.4 liters or 22,400 cm^3
• What is a homogeneous mixture? Give one example
• Homogeneous mixtures contain uniform composition throughout

  Example: Sugar solution